V. The Latest Revolution in Natural Science and Philosophic Idealism

A year ago in Die Neue Zeit (1907, No. 52), there appeared an article by Joseph Diner-Dénes: “Der Marxismus und die neueste Revolution in der Naturwissenschaft.” The defect of this article is that its author ignored the epistemologic consequences of “recent” physics, a problem in which we are especially interested at present. But it is precisely this defect that renders the viewpoint and conclusions of the author interesting to us. Joseph Diner-Dénes, like the present writer, holds the viewpoint of those “rank and file Marxians” of whom our Machians speak with such grand contempt. For instance, Yushkevich writes that “ordinarily an average, rank-and-file Marxian calls himself a dialectic materialist” (p. 1 of his book). And now such a rank-and-file Marxian, in the person of Diner-Dénes, directly compares the latest discoveries in science, especially in physics (x-rays, Becquerel rays, radium, etc.) with Engels’ Anti-Dühring. To what conclusion did this comparison lead him? “In the various domains of natural science,” writes Diner-Dénes, “new scientific acquisitions have been made, and all of them confirm the proposition which Engels particularly stresses, namely, that in nature, there are no irreconcilable contradictions, no fixed lines of demarcation and distinction,” and that if certain contradictions and distinctions are discovered, then their immobility and absoluteness are read into nature by us alone. For instance, it was discovered that light and electricity are only manifestations of one and the same force of nature. Each day it becomes more probable that chemical affinity may be reduced to electrical processes. The apparently indestructible and the unanalysable elements of chemistry, whose number continued to grow, as if to deride the notion of a world-unity, is proven to be destructible and analysable. The scientists have succeeded in converting the element of radium into that of helium. “Just as all the forces of nature have been reduced to one force, so also may the various kinds of nature’s substances be reduced to one substance.” Having cited the opinion of one of the writers who regards the atom as a condensation of ether, the author exclaims: “What a brilliant confirmation of Engels’ remark ‘that motion is a form of material being.’ All the phenomena of nature are the result of various kinds of motion, and the differences between them lies in the fact that we, as men, perceive this motion in different forms. . . . Matter is exactly as Engels characterised it. Nature, like history, is subject to the dialectic laws of motion.”

On the other hand, you cannot read anything by or about the Machians without encountering allusions to the new physics which, it is believed, has supposedly refuted materialism, etc. How these references are substantiated is another question; but the connection of recent physics, or rather of a certain school of recent physics, with Machism and other varieties of modern idealistic philosophy, is beyond doubt. To analyse Machism and to ignore this connection—as Plekhanov did—is to fail to take the spirit of dialectic materialism seriously, that is, to sacrifice Engels’ entire method for the sake of this or that single letter of his. Engels says explicitly that “with each epoch-making discovery in the department of natural science (‘not to speak of the history of mankind’), it (materialism) has been obliged to change its form” (Feuerbach, p. 65). Hence, the revision of “form” in Engels’ materialism, the revision of his naturo-philosophic views is to be considered not as “revisionism” in the ordinary sense, but, on the contrary, as the kind of “revisionism” which is an integral part of Marxism. We criticise the Machians not for such revision but for their purely “revisionist” method—a method which consists in undermining the substance of materialism, under the pretext of criticising its form. We criticise them for adopting the presuppositions of the reactionary bourgeois philosophy without the slightest attempt to take account directly, frankly and definitely of such essential and significant assertions of Engels on this question, as, for example, the following: “. . .Matter without motion is unthinkable.”

It must be clear that in analysing the question regarding the connection between one school of recent physicists and the revival of idealism, we are far from the thought of even slightly treating the special doctrines of physics. We are exclusively interested in the epistemological conclusions which follow from certain definite positions and quite generally known discoveries. These epistemological inferences seem so directly involved in the subject matter, that many a physicist has already treated them. And what is more, amongst the physicists themselves there are already various tendencies, and certain schools are being formed on this ground. Our object, then, is to propound clearly the divergent views of these tendencies and examine their relation to the fundamental alignments in philosophy.

Henri Poincaré, the famous French physicist, says in his book that there are “symptoms of a serious crisis” in physics, and devotes a special chapter to it (Chap. VIII). This crisis is not confined to the proposition that the “grand revolutionist, radium” has undermined the principle of the conservation of energy. “Other sciences are equally in danger” (p. 96). For instance, the principle of Lavoisier, or the principle of conservation of mass, has been undermined by the electron theory of matter. According to this theory the atoms are composed of very minute particles, charged with positive or negative electricity, called electrons and “are immersed in a medium which we call ether.” The experiments of the physicists offer material for the calculation of the velocity of the electrons and the measurement of their mass (or the relation of their mass to their electrical charge). The velocity of this motion proves to be comparable with the velocity of light (300,000 kilometres per second), in fact, amounts to one-third of the latter’s speed. In the presence of such conditions we must take into account the two aspects of the mass of the electron according to the necessity of overcoming the inertia of (1) the electron itself and (2) the ether. The first mass will be the real or mechanical mass of the electron, the second will be the “electrodynamic mass which represents the inertia of ether.” And here the first mass proves to be equal to zero. The entire mass of electrons, or, at least, of the negative electrons, proves to be in its origin, totally and exclusively electrodynamic. Mass disappears. The foundations of mechanics are undermined. The principle of Newton, the equality of action and reaction, go by the board.

We have before us the “ruins” of the old principles of physics, “a general destruction of principles.” It is true, he corrects himself, saying that all the exceptions to the principles belong to the realm of infinitesimal quantities; that it is possible that we are still ignorant of other infinitesimals which would counteract the destructive effects of the old principles. And besides, radium is still very rare. But at any rate we have reached a “stage of doubt.” We have already made the acquaintance of the author’s epistemologic inferences from this “stage of doubt.” “It is not nature which gives, or dictates, to us the ideas of space and time, but we give them to nature; whatever is not thought, is the purest zero.” These are idealist inferences. The destruction of the fundamental principles shows—such is the trend of Poincaré’s thought—that these principles are not copies, not reflections of nature, not pictures of something external in relation to man’s mind, but products of this mind. Poincaré does not develop those inferences consistently, does not take an interest in the essentially philosophic side of the question. Abel Rey, the French writer on philosophic problems, treats this question in detail. True, the author himself is a positivist, that is, a muddlehead and a half-Machian, but in this case it is even better, for he cannot be suspected of the desire to “slander” the idol of our Machians. Rey cannot be trusted when the question is an exact definition of philosophic concepts and particularly of materialism, for Rey too is a professor, and as such is imbued with a feeling of contempt for the materialists. (His ignorance of the epistemology of materialism is extreme.) That this “man of science” should be unaware of the existence of a certain Marx or Engels is out of the question. Yet Rey consulted carefully and conscientiously the extremely abundant literature on the question, not only in French, but in English and German as well (Ostwald’s and Mach’s works especially). We shall often avail ourselves of his references.

The attention of philosophers in general, says the author, and particularly of those who, for one reason or another, wish to criticise science in general, is now directed to physics. “In discussing the limits and validity of physical knowledge, it is, in fact, the legitimacy of positive science, the possibility of knowledge of the object, that is discussed” (pp. i-ii). From the “crisis of modern physics” we hasten to draw sceptical conclusions (p. 14). Now, in what does this crisis consist? During the first two-thirds of the nineteenth century the physicists had agreed on fundamental concepts. “They believed in a purely mechanical explanation of nature; they assumed that physics is nothing but a complication of mechanics, namely, molecular mechanics. They did not differ unless it was as to the procedure employed to reduce the physical to the mechanical, as to the details of the mechanism [p. 16]. . . . At present it seems that the spectacle which the physico-chemical sciences offer us, is completely changed. Extreme disagreements have replaced the former unity, and those disagreements are not infrequent, not in details, but in the leading and fundamental ideas. Even if the statement that each scientist has his peculiar tendencies were an exaggeration, we must admit, however, that like art, science, too, especially physics, has numerous schools, whose views are often far removed from one another and sometimes even violently opposed. . . .

“From this one may judge the far-reaching significance of what is called the crisis in modern physics and the extent of its scope.

“Until the middle of the nineteenth century, traditional physics had been convinced that a mere extension of the familiar methods of physics would suffice to account for the metaphysics of matter. This physics ascribed to its theories an ontological significance. And these theories were wholly mechanistic. The traditional ‘mechanism’ [Rey employs this word in the special sense of a system of views, which reduces physics to mechanics] thus claimed over and above the results of experience, a real knowledge of the material world. This was not an hypothetical account of experience—it was a dogma” (p. 16).

We must here interrupt the honourable “positivist.” It is clear that he is referring to the materialistic philosophy of traditional physics, without wishing to call the devil (materialism) by name. To a Humean, materialism is metaphysics, dogma, a transcendence of the limits of experience. Without knowing what materialism really is, the Humean Rey can have no notion of dialectics, and of the distinction between dialectic materialism and metaphysical materialism, as formulated by Engels. The correlation, therefore, between absolute and relative truth, for example, is absolutely unclear to Rey.

“The critical observations directed against the traditional mechanism, which were expressed in the second half of the nineteenth century, weakened the position of the ontological reality of mechanism. On the basis of these criticisms a philosophic conception of physics which became almost traditional with philosophy at the end of the nineteenth century, established itself. Science was nothing but a symbolic formula, a method of denotation (repérage), and as the methods of denotation vary according to schools, the conclusion was soon reached that only that could be denoted which was previously designed by man as capable of denotation. Science became a work of art for dilettantes, a work of art for the utilitarians—an attitude which implies the negation of the possibility of science. Science, as a pure ‘artifact,’ as mere utilitarian technique, had no right, without perverting the sense of the words, to call itself science. To say that science can be nothing, save such an artifice, is to disavow science in the proper sense of the word.

“The rejection of traditional mechanism, or, to be more precise, the criticism to which it was subjected, involved this proposition: science itself is in a critical position. From the impossibility of adhering to a pure and simple traditional mechanism it was concluded that science was impossible” (p. 17). And the author poses the question: “Is the actual crisis of physics a temporary and external incident in the evolution of science, or is it science itself which has taken a sudden turn and abandoned the path it has followed hitherto? [p. 18].

“If these sciences, which historically have been emancipators, suffer a crisis which reduces them to nothing save valuable, technically useful recipes; if they are stripped of their entire significance, then from the standpoint of natural knowledge the result must be a complete overthrow of the methods of logical and historical analysis of ideas. Physics loses then all educational value; the positive spirit which it represents now becomes false and dangerous.” Science is able to offer no true knowledge save practical recipes. “The cognition of the real must be sought by other means. . . . We must take another road, and turn to subjective intuition, to the mystical sense of reality, in a word, to the mysterious, to what we had thought had been given its death-blow by science” (p. 19).

As a positivist the author considers such a view to be wrong and the crisis of physics only temporary. We shall see how Rey vindicates Mach, Poincaré and the others from such aspersions. At present we limit ourselves to stating the fact of the “crisis” and its significance. From the last words of Rey it is quite clear, who the reactionary elements were who availed themselves of this crisis and made it still more acute. In the preface to his work, Rey directly says that “the fideist and anti-intellectualist movement of the last years of the nineteenth century seek support in the general spirit of modern physics” (p. 2). In France those are termed fideists who rely more upon faith than upon reason. By anti-intellectualism is meant the doctrine which denies the claims or pretensions of reason. Hence, in its philosophic aspect, the substance of the “crisis of modern physics” arises from the fact that the old physics regarded its theories as “a real presentation of the material world,” that is, as a reflection of objective reality. The new movement in physics sees in scientific theory only symbols, signs, and prescriptions for practice; it denies the existence of objective reality independent of our consciousness and reflected in it. Had Rey adhered to a correct philosophic terminology, he would have said: the materialistic theory of knowledge, which had been instinctively accepted by traditional physics, was changed for an idealistic and agnostic one, and fideism availed itself of this, despite the efforts of the idealists and agnostics.

But Rey does not present this change, which constitutes the crisis, as if all modern physicists stand opposed to traditional physics. Nay, he shows that according to their epistemologic tendencies the modern physicists are divided into three schools: energetic or conceptualist (from the word concept which means pure idea); mechanistic or neo-mechanistic, to which the preponderant majority of physicists adhere; and intermediate between the two, the critical school. To the first belong Mach and Duhem; to the third, Henri Poincaré; to the second, Kirchhoff, Helmholtz, Thomson (Lord Kelvin) Maxwell—among the old; Larmor and Lorentz—among the more recent. What the difference between the two basic alignments is (for the third is not really an independent position but intermediate between the other two) may be judged from the following words of Rey:

“Traditional mechanism constructed a system of the material world. In its doctrine of the structure of matter, it resorted to the conception of ‘elements which were qualitatively homogeneous and identical,’ elements which had to be regarded as ‘immutable and impenetrable,’ etc. Physics ‘constructed a real edifice with real material and real cement.’ The physicist thought he knew the material elements, their operating causes, the ways in which they worked, and the real laws of their action [pp. 33-39]. . . . This outlook has been changed mainly in that the ontological validity of the theory is now abandoned and the phenomenological part stressed instead. The conceptual view has to deal with ‘pure abstractions.’ It searches for a purely abstract theory which eliminates, as much as possible, the hypothesis of matter. . . . The notion of energy becomes the fundamental structure of recent physics, and therefore conceptualist physics may in most cases be called with Mach, energetics” (p. 46).

Rey’s confusion of energetics and Machism is incorrect, of course, just as is his assurance that despite the sharp disagreement with the conceptualists, the neo-mechanistic school approaches the phenomenalist view of physics (p. 48). The “new” terminology of Rey does not clarify, but obscures matters; still we were not able to avoid it in order to convey to the reader the “positivist’s” view of the crisis in physics. The substance of the question at issue between the “new” and the old school is the same, as the reader can convince himself, as that revealed in the above quoted criticism of Helmholtz by Kleinpeter. In presenting the views of various physicists, Rey reflects all the indefiniteness and vacillation of their philosophic attitudes in his exposition. The essence of the crisis of modern physics consists in the destruction of the old laws and basic principles, in the rejection of an objective reality existing outside of mind, that is, in the change from materialism to idealism and agnosticism. “Matter has disappeared”—that is how the fundamental and typical embarrassment in the several questions which created this crisis may be characterised. We shall pause upon this embarrassment.

The literal expression, “matter has disappeared,” may be found in the description given by the recent physicists of the latest discoveries, as, for instance, in Houllevigue’s book, L’evolution des sciences. “The atom dematerialises, matter disappears.” To see how easily the fundamental philosophic implications are drawn by the Machians, let us take Valentinov. He writes: “The statement that the scientific explanation of the world receives a firm foundation only in materialism is nothing but a fiction, and an absurd fiction at that” (p. 67). As the destroyer of this absurd fiction they point to the well-known Italian physicist, Augusto Righi, who says that the theory of electrons “is not so much a theory of electricity, as of matter; the new system merely puts electricity in the place of matter.” Having quoted these words (p. 64), Mr. Valentinov exclaims: “Why did Righi allow himself to offend holy matter? Because he is perhaps a solipsist, or an idealist, a bourgeois criticist, or a certain empirio-monist or even something worse than that?”

This remark, which seems to Valentinov to be fatal to the materialists, discloses his virgin innocence of what the real question of materialism is. What is the real connection between idealism and the “disappearance of matter”?—this Mr. Valentinov does not understand at all. And this “disappearance of matter,” which he repeats after the modern physicists, has no relation to the epistemologic distinction of materialism and idealism. To throw light upon it, let us take one of the clearest and most consistent Machians, Karl Pearson. He conceives the physical realm to be constituted of groups of sense impressions. He illustrates “our conceptual model of the physical universe” in the following diagrammatic manner, making it plain that the relation of size is not taken into consideration by the diagram:

To simplify his diagram, Pearson eliminates the question of the correlation of ether and electricity or positive and negative electrons. But this is not important. What is important is that according to Pearson’s idealistic viewpoint, “bodies” are sense-perceptions; whereupon the constitution of these bodies of particles, and particles of molecules and so forth, concerns the changes in the model of the physical world, and not at all the question whether bodies are symbols of perception, or perceptions the images of bodies. Materialism and idealism are distinguished by their respective solution of the problem concerning the source of our knowledge and the relation of knowledge (or the “psychical” at large) to the physical realm; and the question of the structure of matter, of atoms and electrons is something that concerns only “this physical world.” When the physicists say “matter disappears,” they mean by this that, until the present the natural sciences had reduced their measurements of the physical realm to three ultimate concepts: matter, electricity and ether; and that now only the last two remain, for they have finally succeeded in reducing matter to electricity. The atom is explained as being the simulacrum of the infinitely small solar system within which the negative electrons move around the positive electron with a definite (and immeasurably immense) velocity. Instead of scores of elements they consequently have succeeded in reducing the physical realm to two or three elements (insofar as the positive and negative electron constitute “two kinds of essentially distinct matter,” as the physicist Pellat says (loc. cit., pp. 294-295). Hence the natural sciences lead to the “unity of matter” (ibid.); 7 this is the real meaning of the disappearance of matter, of its change into electricity, etc., which baffles so many people. “Matter disappears’—means that matter in the form of the limit which we have known up to now vanishes, as our knowledge penetrates deeper; those properties of matter which before seemed absolute, immutable, and primary (impenetrability, inertia, mass, etc.) disappear, and now become relative, belonging only to certain states of matter. For the sole “property” of matter—with the recognition of which materialism is vitally connected—is the property of being objective reality, of existing outside of our cognition.

The error of Machism in general, and the Machian new physics in particular, is that the foundation of materialism is ignored, together with the distinction between metaphysical materialism and dialectic materialism. The recognition of immutable elements, “of the immutable substance of things,” is not materialism, but is metaphysical, anti-dialectical, materialism. Dietzgen, therefore, stresses the point that the “subject-matter of every science is endless,” that not only the infinite but the “smallest atom” as well, is incommensurable, unknowable to the end, inexhaustible. Engels, therefore, adduced his example regarding the discovery of alizarine in coal tar and criticised mechanistic materialism. To put the question from the only correct, that is, the dialectico-materialistic standpoint, we must ask: do electrons, ether, etc., exist as objective realities outside of the human mind? The scientists must answer this question without hesitation and the answer must be an affirmative one, for they recognise without hesitation the existence of nature prior to man and organic matter. Thus is the question decided on the side of materialism, for the idea of matter, as we already stated, epistemologically means nothing new, besides some objective reality existing independently of the human mind and reflected by it.

But dialectical materialism insists on the approximate, relative character of every scientific proposition concerning the structure of matter and its properties; on the absence of absolute boundaries in nature; on the transformation of moving matter from one state to another, which from an ordinary viewpoint appears evidently irreconcilable, etc. Amazing as is the transformation of imponderable ether into ponderable matter, to the viewpoint of “common sense,” and conversely, as amazing as the absence of any other kind of mass in the electron save electro-magnetic may appear to it, together with the strange discovery that mechanical laws of motion are limited to only one region of natural phenomena, while the others conform to subtler laws of electro-magnetics and so forth—yet all this for dialectic materialism is only another corroboration of its truth. Recent physics fell into an idealist swamp mainly because the physicists did not know dialectics. They combated metaphysical (in Engels’ sense of the word, and not in the positivist, or Humean) materialism and its one-sided “mechanisation,” and by so doing they not only threw the water out of the bath, but the child as well. By denying the immutability of the elements and the properties of matter known hitherto, they ended with the denial of matter, the denial of the objective reality of the physical world. By denying the absolute character of the most important and basic laws, they ended in the denial of every objective law, in the declaration of the natural law as a mere conventionality, “a limit of expectancy,” “a logical necessity,” and so forth. By insisting on the approximate, relative character of our knowledge, they ended in the denial of the object existing independently of cognition, an object which is reflected in knowledge with an approximate degree of truth. And so forth, and so on without end.

Bogdanov’s discussions in 1899 about “the immutable essence of things,” Valentinov’s and Yushkevich’s discussions about “substance”—these are fruits of the ignorance of dialectics. Only one thing is, from Engels’ viewpoint, immutable—the reflection by the human mind (when the human mind exists) of a world existing and developing independently of the mind. No other “immutability,” no other “essence” or “absolute substance,” in the sense in which the idle official philosophy portrayed these, existed for Marx and Engels. The “essence” of things or their “substance” is also relative, it expresses only the degree of man’s power penetrating into and knowing objects; and even if yesterday this penetration did not go any further than the atom, and to-day, no further than the electron and ether, then dialectic materialism insists on the temporary, relative, approximate character of all these milestones on the road of knowledge of nature, through the progressive science of man. The electron is as inexhaustible as the atom, nature is infinite, but it exists infinitely; and only this categorical, unconditional recognition of its existence beyond the consciousness and sensation of man, distinguishes dialectic materialism from relativist agnosticism and idealism.

Let us cite two examples of the way the new physics vacillates unconsciously and instinctively between dialectic materialism, which remains unknown to the bourgeois savants, and “phenomenalism” with its inevitably subjectivist (and directly fideist) inferences.

The same Augusto Righi, whom Valentinov was unable to ask the question which interested him, the question about materialism, writes in the preface to his book:

“What those electrons and electrical atoms properly are has remained a mystery until now; but regardless of this it may, perhaps, be the lot of the new theory to attain with time a philosophic significance, in so far as it arrives at absolutely new hypotheses regarding the structure of ponderable matter and strives to reduce all phenomena of the external world to one common origin.

“From the standpoint of the positive and utilitarian tendencies of our time such privilege, is, if you please, not insignificant, and the theory may be recognised before everything else as a convenient means to introduce order and to compare facts, to serve as a guide in the search for further phenomena. But if in former times they had too much confidence in the faculties of human spirit and thought which quite easily embraced the last causes of all things, in our time, however, there is a tendency to fall into a contrary error’ (loc. cit., p. 3).

Why does Righi separate himself from the positivist and utilitarian tendencies? Because, not having obviously any definite philosophic viewpoint, he instinctively clings to the reality of the outer world and to the recognition of the new theory, not only because it is “convenient” (Poincaré), not only because it is “empirio-symbolic” (Yushkevich), not only for the reason that it “harmonises” experience (Bogdanov), or whatever else the names of similar subjectivist tricks may be, but because it is a further step in the knowledge of objective reality. If this physicist were to acquaint himself with dialectic materialism, his judgment of the error of old metaphysical materialism, would, perhaps, become the starting point of a correct philosophy. But the entire environment in which these people live estranges them from Marx and Engels, casts them into the arms of the vulgar official philosophy.

Nor is Rey himself any more familiar with dialectics. But he too was compelled to state that amongst recent physicists there are those who are regarded as the successors to the traditions of “mechanism” (materialism). The path of “mechanism” follows not only Kirchhoff, Hertz, Boltzmann, Maxwell, Helmholtz and Lord Kelvin. “Pure mechanists, and many more among those who represent the last word in mechanism, as, e. g., those who follow Lorentz and Larmor, formulate an electric theory of matter and arrive at the denial of the constancy of mass, making it a function of motion. All of them are mechanists, because they take real motion as their starting point” (Rey’s emphasis, pp. 290-291). “. . .If, for example, the recent hypotheses of Lorentz, Larmor and Langevin were confirmed, in virtue of certain experimental concordance, and were to attain a sufficiently stable basis for the systematisation of physics, it is certain that the modern mechanical laws would depend upon the laws of electro-magnetism; they would only form a special case within well-determined limits. The constancy of mass and the principle of inertia would hold good only for the average velocities of bodies, taking the term ‘average’ in relation to our senses and the phenomena which constitute our general experience. A general change of mechanics would become necessary, and hence, a general change in physics as a systematic science.

“Would it signify the abandonment of mechanism? By no means. The pure mechanistic tradition would continue to persevere, and mechanism would follow its normal course of development” (p. 295).

“The electronic physics, which should be ranged amongst the mechanist theories in view of its general spirit, tends to impose a maximum systematisation upon physics. Its spirit is mechanistic though the fundamental principles of physics are not furnished by mechanics but by experimental data of electricity, because (1) it employs material and figurative elements in order to represent the physical properties and their laws; it expresses itself in terms of perception.

“(2) If it does not consider physical phenomena as particular cases of mechanical phenomena, it considers the mechanical phenomena as particular cases of physical phenomena. The laws of mechanics are always in direct connection with the physical laws; and mechanist notions remain of the same order as the physico-chemical notions. In the traditional mechanism these notions were copies of the relatively slow motions which, because they alone had been directly observable, were taken as types of all possible motions. New experiments showed that it was necessary to extend our conception with regard to all possible motions. Traditional mechanics remains entirely intact, but it is applied only to relatively slow motions. . . . In relation to great velocities, the laws are different. Matter is reduced to electrical particles, the ultimate elements of the atom. . . .

“(3) Motion, as displacement in space, remains a uniquely typical element in physical theory.

“(4) And, finally, from the viewpoint of the general spirit of the science of physics and its methods, this conception of the science of physics, its methods, its theories and their relation to experience—remains more than any other, absolutely identical with the views of mechanism, and the theory of physics, which was ushered in with the Renaissance” (pp. 46-47).

This long quotation from Rey is given because due to his constant fear of “materialist metaphysics,” it would be impossible differently to expound his assertions. But though Rey, and the physicists of whom he speaks, may renounce materialism, it is nevertheless quite certain that traditional mechanics was a “copy” of motions of moderate velocity, while recent physics is “a copy” of motions of enormous velocity. The recognition of the theory as a copy, as an approximate reflection of objective reality, is materialism. When Rey says that amongst the recent physicists there “is a reaction against the conceptual [Machian] and energetics school,” and when he regards the physicists of electron theory as the representatives of this reaction (p. 46), a better corroboration could not be desired of the fact, that the struggle is essentially between the materialist and idealist tendencies. But we must not forget that, besides the common prepossessions of all educated philistinism against materialism, in the case of the most outstanding theoreticians, it is combined with an absolute ignorance of dialectics as well.

The utilisation of the new physics by idealism and the tendency to draw idealist conclusions therefrom, are the result not of the discovery of new kinds of substance and force, matter and motion, but of the attempt to conceive motion without matter. It is essentially the futility of this attempt that our Machians fail to comprehend. They refused to take account of Engels’ proposition, that “motion without matter is inconceivable.” Joseph Dietzgen in 1869 expressed this idea, as did Engels, in his Nature of Human Brain Work; it is true not without his characteristically confused attempts to “reconcile” materialism and idealism. Let us disregard these attempts, which are sufficiently explained by the fact that Dietzgen waged a polemic against the anti-dialectic materialism of Büchner, and see what position Dietzgen took on the question which interests us at present. He says: “They [idealists] like to have the general without the individual, spirit without matter, force without substance, science without experience or material, the absolute without the relative” (loc. cit., p. 124).

Thus Dietzgen recognises the attempts to separate motion from matter, force from substance, as idealism and puts it into the same category as the separation of thought from the brain. “Liebig,” he continues, “who is especially fond of straying from his inductive science into the field of speculative thought, says in an idealist sense: ‘Force cannot be seen’ [p. 125]. . . . The spiritualist or the idealist believes in a spiritual force whose nature is ghostlike and inexplicable [p. 126]. . . . The contradistinction between force and matter is as old as that between idealism and materialism [p. 127]. . . . True, there is no force without matter, no matter without force. Forceless matter and matterless force are nonentities. If there are idealistic naturalists who believe in the existence of immaterial forces then we say that to that extent they are not naturalists . . . but spiritualists” (pp. 130-131).

From this we see that forty years ago there were also naturalists, ready to recognise the possibility of motion without matter, and that Dietzgen considered them to “that extent” spiritualists. What, then, is the connection of idealism with the separation of matter from motion, with the elimination of substance from force? Does it not lie in the fact that it really is “more economical” to think of motion without matter?

Let us imagine a consistent idealist who holds that the world is his sensation, or idea. (If we take “nobody’s” sensation or idea, only the variety of idealism will change, but not its substance.) The idealist would not think of denying that the world is motion, i. e., the movement of his thoughts, ideas, sensations. The question “What is being moved?” the idealist will spurn and consider as absurd. What really takes place, he would say, is this: My sensations change, my ideas come and go, and nothing more. Outside of me there is nothing. “It moves”—and that is all. It is hardly possible to conceive of a more “economical” way of thinking. And by no proofs, or syllogisms, or definitions would it be possible to refute the solipsist, if he consistently adhered to this view. The basic distinction between the materialist and the idealist is that the materialist takes sensation, perception, conception and, in general, human consciousness as the copy of objective reality. The world is the movement of this objective reality reflected in our consciousness. To the movement of ideas, perceptions, etc., corresponds the movement of matter outside of us. The notion of matter expresses nothing but objective reality which is given us in sensation. Therefore to separate matter from motion would be the same as separating thought from objective reality, the same as separating sensation from the external world—in a word, would be equivalent to joining the idealist camp. This ruse of recognising motion without matter in order to deny more effectively materialism is only possible because of the silence which is kept about the relation of matter to thought. It would appear as if that relation did not exist, but in reality it is smuggled in, remains unmentioned at the very beginning of the argument, and subsequently crops up more or less imperceptibly.

They tell us that matter has disappeared, and wish to draw epistemologic conclusions therefrom. “And has thought itself remained?” we ask. If not, if with the disappearance of matter thought has also disappeared, if with the disappearance of the brain and nervous system our ideas and sensations, too, have vanished, then it means that everything has disappeared. So does the argument together with whatever “thought”—or thoughtlessness—there is in it! If thought has remained, if you assume that with the disappearance of matter, thought, idea, sensation, etc., do not disappear, then you have secretly embraced the idealist viewpoint. This happens to people who wish, for “economy’s sake,” to conceive of motion without matter, for by implication, from the very fact that they continue their discourse, they recognise the existence of thought after the disappearance of matter. This means that a very simple or a very complex system of idealism is taken as fundamental; very simple, if the position reduces to solipsism (I exist, and the world is only my sensation); very complex, if instead of the thought, idea and sensation of a living man, a dead abstraction is posited, that is, no particular thought, no particular idea, no particular sensation, but thought in general (the Absolute Idea, the Universal Will, etc.), sensation as an indeterminate “element,” the “psychical” which replaces the whole of physical nature, etc., etc. Amongst the varieties of idealism there may be thousands of peculiar shades and kinds and it is always possible to add a thousand and first shade. To the author of this thousand and first puppet system (empirio-monism, for example) its difference from all the other varieties will seem to be very momentous. From the point of view of materialism, however, these distinctions are totally unimportant. Important only is the point of departure. Important only is that the attempt to conceive motion without matter, smuggles in thought separate from matter—this is idealism.

Therefore, the English Machian, Karl Pearson, for example, the clearest and most consistent Machian, inimical to verbal trickery, directly begins the seventh chapter of his book, devoted to “matter,” with the section which bears the name “All things move—but only in conception.” “It is, therefore, for the sphere of perception, idle to ask what moves and why it moves.”

Therefore, in the case of Bogdanov, his philosophic misfortunes began earlier than his acquaintance with Mach. They began when he took the great chemist, but poor philosopher, Ostwald at his word, on the possibility of conceiving motion without matter. To pause on this long past episode of Bogdanov’s philosophic growth is in place here, especially since it is impossible to ignore Ostwald’s “energetics” in speaking of the connection between idealism and certain tendencies in recent physics.

“We have already said,” wrote Bogdanov in 1899, “that the nineteenth century did not succeed in ultimately solving the problem as to ‘the immutable essence of things.’ This essence under the name of ‘matter’ plays an important rôle even in the views of the foremost thinkers of the century.”

We have already said that this represents nothing but confusion. The recognition of the objective reality of the outer world, the recognition of existence, outside of our mind, of eternally moving and eternally changing matter, is here confused with the recognition of the immutable essence of things. It is hardly possible that in 1899 Bogdanov did not include Marx and Engels in the number of the “foremost thinkers.” But he obviously did not grasp their dialectic materialism.

“. . In the processes of nature there are usually two factors to be distinguished: matter and motion. It cannot be said, however, that the notion of matter is very clear. It is impossible to give a satisfactory answer to the question of what matter is. It is defined as the ‘cause of sensations’ or as ‘the permanent possibility of sensation,’ but it is evident that matter is here confused with motion. ii).

It is evident that Bogdanov argues here incorrectly. It is not enough that he confuses the materialist recognition of the objective source of sensations (“cause of sensations” does not clearly enough express this) with Mill’s agnostic definition of matter as the possibility of sensation. But having just reached the question as to the existence or non-existence of an objective source of our sensations, instead of going further, he abandons it without further discussion and hastens to another question as to whether matter without motion is possible or not. The idealist may regard the world as being made up of the motion of our sensations (be it “socially organised” or “harmonious” to the highest degree); the materialist regards the world as motion of an objective source, of which our sensations are the objective model. The metaphysical, that is, the anti-dialectical, materialist may posit the existence of matter (be it “temporary,” “prior to,” the “first impetus,” etc.) without motion. The dialectic materialist, however, not only regards motion as the inseparable property of matter but rejects even the simplified interpretation of motion.

“. . . Such a definition as ‘matter is that which moves’ would, perhaps, prove the most exact; but this is as absurd as saying that matter is the subject of the sentence, whose predicate moves. The fact is, however, that men in the epoch of the beginnings of statics, were wont to see something necessarily solid in the rôle of the subject—a certain object,—while the phenomenon of ‘motion,’ so inconvenient from the outlook of statics, they agreed to tolerate only as predicate, as one of the attributes of matter.”

This is something like Akimov’s accusation against the adherents of Iskra, that in their programme they do not use the word “proletariat” in the nominative case! Whether we say that “the world is moving matter,” or “the world is material movement,” it will not change the issue.

“. . . But energy must have a vehicle! say those who believe in matter. Why? asks Ostwald reasonably. Must nature necessarily consist of subject and predicate?” (p. 39).

Ostwald’s answer, which pleased Bogdanov so much in 1899, is plain sophistry. “Must our hypotheses consist of electrons and ether?” we could retort upon Ostwald. In reality, matter, as the “subject” can only be eliminated by mind from “nature,” only because thought as the “subject” (as the prius, as independent of matter) is taken as the starting point in philosophy. Not the subject, but the objective source of sensation is eliminated and sensation becomes the “subject,” that is, philosophy inevitably becomes Berkeleian, no matter how “profoundly” the word “sensation” is weighted. Ostwald attempted to escape this inevitable philosophic alternative—materialism or idealism—through the ambiguous use of the word “energy,” but this attempt was precisely as futile as similar contrivances. If energy is motion, then you only shift the difficulty from the subject to the predicate, you have only changed the question from “Does matter move?” to “Is energy material?” Does this transformation of energy outside of my consciousness take place independently of man and mankind, or are these only ideas, symbols, conventional marks, etc.? This attempt to avoid old epistemologic errors merely by a “new” terminology proves fatal to the philosophy of “energetics.”

Here are examples of how Ostwald, the philosopher of energetics, became muddled. In the preface to his book, he declares that he would “consider it a great gain should the old problem of how to connect the conceptions of matter and spirit” be simply and naturally eliminated, should both concepts be subsumed under the concept of “energy.” But this would not be a gain, but a loss, because the question of whether epistemological investigation (Ostwald does not clearly see that he has asked an epistemological, and not a chemical, question) is to be led in the materialist or idealist direction, is not solved but confused by the arbitrary substitution of the term “energy.” Of course, if we “subsume” under this concept matter and spirit, then the verbal annihilation of the distinction is beyond doubt, but the absurdity of the notion of “brownies and fairies” does not vanish simply because it is called “energetics.” On page 394 of the Vorlesungen we read: “That all outer phenomena can be presented as energy processes can most simply be explained by the fact that the processes of our consciousness themselves are energetical and they impose such a property upon all outer experiences.” This is pure idealism: our thought does not reflect the transformation of energy in the external world, but the external world reflects a certain “property” of our consciousness! The American philosopher, Hibben, pointing to this and similar passages in Ostwald hit the mark in saying that Ostwald “appears, moreover, in Kantian disguise—that the phenomena of the external world become intelligible only through the fundamental forms which thought imposes upon them. . . . It is obvious therefore that if the primary concept of energy is so defined as to embrace psychical phenomena, we have no longer the simple concept of energy as understood and recognised in scientific circles or even among the Energetiker themselves” (p. 330). The transformation of energy is analysed by science itself as an objective process, independent of the consciousness of man and the experience of mankind, that is, in materialistic fashion. And Ostwald himself in a number of instances probably in the majority of instances, means by energy nothing but matter in motion.

Thereupon occurred a rare event! The disciple of Ostwald, becoming Mach’s disciple, began to reproach Ostwald not because of inconsistency in inclining towards a materialistic interpretation of energy, but because he lays himself open to such an interpretation (energy sometimes is made the basis of the materialist view). The materialists criticise Ostwald because he relapses into idealism, because he attempts to reconcile materialism and idealism. Bogdanov criticises Ostwald from the idealist viewpoint. In 1906 he wrote: “. . . Hostile to atomism, but in the rest greatly akin to the old materialism, Ostwald’s energetics at first enlisted my heartiest sympathy. But I soon noticed an important contradiction in his Naturphilosophie. Often emphasising the purely methodological significance of the conception of “energy,” in a great number of instances he himself is not consistent in his own view. From a pure symbol of correlations of facts of experience, energy is converted into the substance of experience, into the material stuff of the world. . .”

Energy is a pure symbol! After this Bogdanov can dispute as much as he pleases with the “empirio-symbolist” Yushkevich, with the “pure Machians,” with the empirio-criticists, etc. From the standpoint of the materialists they will be regarded as disputes between two people, one of whom believes in a yellow devil, and the other in a green one. The differences between Bogdanov and the Machians are not important, but what they share in common—is very important. They are—an idealist interpretation of “experience” and “energy,” the denial of an objective reality through the processes of adaptation to which human experience arises, and the denial that the sole scientific “methodology” and scientific “energetics” consists in reflecting this objective reality.

“The material of the world is indifferent to it [Ostwald’s energetics]. Both the old materialism and panpsychism are perfectly compatible with it” (p. xvii). And Bogdanov changed from a “muddled energetics” not to the materialist but the idealist camp. “When energy is presented as substance then it is nothing else than the old materialism minus the absolute atoms—materialism with a correction in the sense of the continuity of the existent” (ibid.). Yes, from the “old” materialism, that is, from the metaphysical materialism of the naturalists, Bogdanov goes, not to dialectic materialism which in 1906 he understood as little as he did in 1899, but to idealism and fideism; for against the “methodological” conception of energy, against its interpretation as a “pure symbol of correlation of the facts of experience,” not one enlightened representative of modern theism, not one follower of the immanentist school, not one “neo-criticist,” will object. Take Paul Carus, whose acquaintance we have already made, and you will see that this Machian criticises Ostwald in the manner of Bogdanov: “Materialism and energetics are in the same predicament.” “We are helped very little by materialism when we are told that everything is matter, that bodies are matter, and that thoughts are merely a function of matter, and Professor Ostwald’s energetics is not a whit better when it tells us that matter is energy, and that the soul too is only a factor of energy” (p. 533).

Ostwald’s energetics is a good example of how quickly the “new” terminology becomes fashionable; and as quickly proves that a slightly different mode of expression does not at all wipe out the distinctions between fundamental philosophic questions and tendencies. Through the use of the term “energetics” it is just as possible to express both materialism and idealism (more or less consistently, of course) as it is through the term “experience” and the like. The physics of energetics has been the source of new idealist attempts to conceive of motion without matter. It has seized upon the occasion of the decomposition of those particles of matter which have been hitherto accounted as impossible of decomposition, and upon the discovery of the heretofore invisible forms of material movement.

In order to show concretely the philosophic battle which is being waged in modern literature as a consequence of the several implications which follow from recent physics, we shall let the participants in the “battle” speak for themselves, beginning with the English combatants. The physicist, Arthur W. Rücker, defends one tendency from the point of view of the natural sciences; the philosopher, James Ward, another tendency, from the point of view of epistemology.

At the convention of the English naturalists at Glasgow in 1901, Rücker, the president of the physics section, chose as the topic of his inaugural address, the question concerning the validity of physical theory, concerning the doubts which have arisen as to the existence of atoms and especially of the ether. The speaker referred to those who had taken up the problem, namely, to the physicists Poincaré, Poynting (the English adherent of the symbolists or Machians), the philosopher Ward, and to the celebrated book of Haeckel’s and finally presented his own views.

“The question at issue is whether the hypotheses which are at the base of the scientific theories, now most generally accepted, are to be regarded as accurate descriptions of the constitution of the universe around us, or merely as convenient fictions.” (No. 1345—That is to say, in terms of the question at issue with Bogdanov, Yushkevich and the others, whether or not physical theory is a copy of objective reality, of moving matter, or whether it is only a “methodology,” a “pure symbol,” a mere “form of the organisation of experience.”) Rücker agrees that it may turn out that practically there is no difference between both theories; the direction of a river can be determined just as well by one who only examines the blue streak on a map or diagram, as by one who knows that this streak represents a real river. Theory, from the standpoint of a convenient fiction, may be regarded as an “aid to memory,” as “a means for producing apparent order out of disorder by codifying the observed facts and laws in accordance with an artificial system, and thus arranging our knowledge under a comparatively small number of heads.” We can confine ourselves to defining heat as a form of motion or energy. “By using this phraseology, we exchange a vivid conception of moving atoms for a colourless statement of heat energy, the real nature of which we do not attempt to define.” Fully recognising the possibility of great scientific achievements in this direction, Rücker “ventures to assert that the exposition of such a system of tactics cannot be regarded as the last word of science in the struggle for the truth. The questions still force themselves upon us: Can we argue back from the phenomenon displayed by matter to the constitution of matter itself; whether we have any reason to believe that the sketch which science has already drawn is to some extent a copy, and not a mere diagram of the truth?”

Analysing the problem of the structure of matter, Rücker takes air as an example, saying that it consists of gases and that science resolves “an elementary gas into a mixture of atoms and ether. . . . There are those who cry ‘Halt’; molecules and atoms cannot be directly perceived; they are mere conceptions, which have their uses, but cannot be regarded as realities.”

Rücker meets this objection by referring to one of any number of instances in the history of science: the rings of Saturn appear to be continuous masses when observed through a telescope. The mathematicians prove by calculation that this is impossible, and spectral analysis corroborates the conclusions reached on the ground of the calculations. Another objection: atoms and ether are endowed with properties which our senses do not disclose as being possessed by ordinary matter. Rücker answers this, also, by referring to such phenomena as the diffusion of gases and liquids. A series of facts, observations and experiments prove that matter consists of separate particles or grains. Whether these particles and atoms are “mere fragments of matter” engulfed in the surrounding ether, or whether they are parts of this medium in a particular state, is so far an open question, and does not bear upon the theory of whether atoms exist or not. There is no ground to deny a priori, against the evidence of experience, that “quasi-material substances” exist, which are different from ordinary matter (atoms and ether). Particular errors are inevitable, but the bulk of scientific data leaves no room for doubt about the existence of atoms and molecules.

Rücker then points to the new experimental data on the structure of atoms and corpuscles (electrons), which are charged with negative electricity, and notes the similarities in the various results of calculating the size of molecules: the “first approximation” gives a diameter of one millionth of a millimeter. Omitting his remarks and criticism of neo-vitalism, we quote his conclusions:

“Those who belittle the ideas which have of late governed the advance of scientific theory, too often assume that there is no alternative between the opposing assertions that atoms and the ether are mere figments of the scientific imagination, and that, on the other hand, a mechanical theory of the atoms and the ether, which is now confessedly imperfect, would, if it could be perfected, give us a full and adequate representation of the underlying realities. For my own part I believe that there is a via media [loc. cit., No. 1346]. . . .A man peering into a darkened room may unclearly discern the objects, but if he does not stumble over the furniture and does not walk into a looking glass as into a door, that means that he sees correctly. We ought, therefore, neither to disregard the pretence to penetrate deeper than the surface of nature, nor pretend that we already fully unveiled the mystery of the world around us.

“It may be granted that we have not yet framed a consistent image either of the nature of the atoms or of the ether in which they exist, but I have tried to show that in spite of the tentative nature of some of our theories, in spite of many outstanding difficulties, the atomic theory unifies so many facts, simplifies so much that is complicated, that we have a right to insist—at all events until an equally intelligible rival hypothesis is produced—that the main structure of our theory is true; that atoms are not merely aids to puzzled mathematicians, but physical realities” (ibid.).

That is how Rücker ended his address. The reader sees that the speaker does not indulge in epistemology, but, in the name of a host of naturalists, he strongly stands up in defence of an instinctive materialist standpoint. The substance of his position is this: the theory of physics is a copy—becoming more exact in time—of objective reality. The world is matter in motion, of which we acquire more and more knowledge in the course of time. The incorrectness of Rücker’s philosophy follows from the conditional defence of the “mechanical” (why not electro-magnetic?) theory, of the ether and his failure to understand the correlation between relative and absolute truth. This physicist lacks knowledge of dialectic materialism (we shall not here consider the environment which causes the English professors to call themselves “agnostics”).

Let us see now how the spiritualist, James Ward, criticises this philosophy:

“Naturalism is no science, and the mechanical theory of Nature, the theory which serves as its foundation, is not science either. . . . Nevertheless, though Naturalism and the natural sciences, the Mechanical Theory of the Universe and mechanics as a science, are logically distinct, yet the two are at first sight very similar, and historically are very closely connected. Between the natural sciences and philosophies of the idealist (or spiritualist) type there is indeed no danger of confusion, for all such philosophies necessarily involve criticism of the epistemological assumptions which science unconsciously makes. . . .” True! The natural sciences unconsciously maintain that their teachings reflect the objective reality, and only such a philosophy is reconcilable with the natural sciences! “. . . Not so with Naturalism, which is as innocent of any theory of knowledge as science itself. In fact Naturalism, like Materialism, is only physics treated as metaphysics. . . . Naturalism is less dogmatic than Materialism, no doubt, owing to its agnostic reservation as to the nature of ultimate reality; but it insists emphatically on the priority of the material aspect of its Unknowable.”

The materialist treats physics as metaphysics! A familiar argument. By metaphysics is meant the recognition of objective reality outside of man; the spiritualists agree with the Kantians and Humeans in such reproaches against materialism. This is understood; for unless the objective reality of things, bodies and objects, known to everyone, be denied, it is impossible to clear the road for “real conceptions” in the spirit of Rehmke!

“‘, . . When the essentially philosophical question, how best to systematise experience as a whole [a plagiarism from Bogdanov?], arises, the naturalist—as we have seen—contends that we must begin from the physical side. Then only are the facts precise, determinate and rigorously concatenated: every thought that ever stirred the human heart . . . can, it holds, be traced to a perfectly definite redistribution of matter and motion. . . . That propositions of such philosophic generality and scope are legitimate deductions from physical science, few, if any, of our modern physicists are bold enough directly to maintain. But many of them consider that their science itself is attacked by those who seek to lay bare the latent metaphysics, the physical realism, on which the Mechanical Theory of the Universe rests. . . . The criticism of this theory in the preceding lectures has been so regarded [by Rücker]. . . . In point of fact my criticism [of this “metaphysics” hateful also to the Machians] rests throughout on the expositions of a school of physicists—if one might call them so—steadily increasing in number and influence who reject entirely the almost medieval realism. . . . This realism has remained so long unquestioned, that to challenge it now seems to many to spell scientific anarchy. And yet it surely verges on extravagance to suppose that men like Kirchhoff or Poincaré—to mention only two out of many distinguished names—who do challenge it, are seeking ‘to invalidate the methods of science!’ . . . To distinguish them from the old school, whom we may fairly term physical realists, we might call the new school physical symbolists. The term is not very happy, but it may at least serve to emphasise the one difference between the two which now specially concerns us. The question at issue is very simple. Both schools start, of course, from the same perceptual experiences; both employ an abstract conceptual system, differing in detail but essentially the same; both resort to the same methods of verification. But the one believes that it is getting nearer to the ultimate reality and leaving mere appearances behind it; the other believes that it is only substituting a generalised descriptive scheme that is intellectually manageable, for the complexity of concrete facts. . . . On either view the value of physics as systematic knowledge about things is unaffected; its possibilities of future extension and of practical application are in either case the same. But the speculative difference between the two is immense, and in this respect the question which is right becomes important . . .” (pp. 304-305).

The question, as put by this frank and consistent spiritualist, is remarkably clear and to the point. Indeed, the difference between the two schools in modern physics is only philosophic, only epistemologic. Indeed, the basic distinction is that one recognises the “ultimate” (it ought to be called objective) reality to be reflected by our theory, and the other denies it, considering theory only as a systematisation of experience, a system of empirio-symbols, etc. Recent physics, having found new aspects of matter and new forms of its motion, asks the old philosophic questions on the occasion of the collapse of the old physical conceptions. And if the adherents of “half-hearted” philosophic tendencies (“positivists,” Humeans, Machians) cannot put the controversial question distinctly, the outspoken idealist Ward, however, has completely unveiled the issue in question.

“. . Sir A. W. Rücker devoted his Inaugural Address to a defence of physical realism against the symbolic interpretations recently advocated by Professors Poincaré and Poynting and by myself [pp. 305-306; and in other parts of his book Ward adds to this list the names of Duhem, Pearson and Mach]. . . . Rücker is constantly talking of ‘mental pictures,’ while constantly protesting that atoms and ether must be more than these. Such procedure practically amounts to saying: In this case I can form no other picture, and therefore the reality must be like it. . . . He allows the abstract possibility of a different mental picture. . . . Nay, he allows ‘the tentative nature of some of our theories’; he admits ‘many outstanding difficulties’! After all, then, he is only defending a working hypothesis, and one, moreover, that has lost greatly in prestige in the last half century. But if the atomic and other theories of the constitution of matter are but working hypotheses, and hypotheses strictly confined to physical phenomena, there is no justification for a theory which maintains that mechanism is fundamental everywhere and reduces the facts of life and mind to epiphenomena—makes them, that is to say, a degree more phenomenal, a degree less real than matter and motion. Such is the mechanical theory of the universe. Save as he seems unwittingly to countenance that, we have then no quarrel with Sir Arthur Rücker” (pp. 314-315).

It is, of course, totally absurd that materialism should maintain the “lesser” reality of consciousness or should necessarily adhere to a “mechanistic” “world-picture” of matter in motion and not an electro-magnetic, or even some immeasurably more complicated one. But in a truly acrobatic manner, much more ably indeed than our Machians (these muddled idealists), did the outspoken and straightforward idealist, Ward, discover the weak points in an “instinctive” naturo-historical materialism, that is, its inability to explain the correlation of relative and absolute truth. Ward resorts to sophistry when he declares that since truth is relative, and approximate, only “groping” towards the essence of things, it cannot reflect reality! But the case for atoms as “working hypotheses” is very clearly put by the spiritualist. Modern, cultural fideism (from which Ward directly derives his spiritualism) has no desire to regard the conceptions of natural science as anything more than “working hypotheses.” We shall concede science to you naturalists, provided you surrender epistemology and philosophy to us—such are the terms of the concubinage under which the theologians and professors in the “advanced” capitalist countries live. For the other points in Ward’s epistemology, which betray the influence of “recent” physics, we must refer to his determined struggle against matter. What is matter? What is energy? asks Ward, mocking at the plethora of hypotheses and the contradictions between them. Is it an ether or ethers?—Or perhaps, some new “perfect liquid” which is arbitrarily endowed with new and improbable qualities. And Ward’s conclusion is: “We find nothing definite except movement left. Heat is a mode of motion, elasticity is a mode of motion, light and magnetism are modes of motion. Nay, mass itself is, in the end, supposed to be but a mode of motion of a something that is neither solid nor liquid nor gas, that is neither itself a body nor an aggregate of bodies, that is not phenomenal and must not be noumenal, a veritable ‘aperion’ on which we can impose our own terms” (Vol. I, p. 140).

The spiritualist is true to himself, and separates motion from matter. The movement of natural bodies has turned out to be upon analysis a movement of something which has not a constant mass, into a movement of an unknown charge of an unknown electricity in an unknown ether. The dialectics of this material transformation which takes place both in the laboratory and the factory, serves in the eyes of the idealist (as in the eyes of the public at large, and those of the Machians) not as a confirmation of the truth of materialist dialectics, but as evidence against materialism: “The mechanistic theory, as a professed explanation of the world, receives its death-blow from the progress of mechanical physics itself” (p. 143). The world is matter in motion, we reply, and the laws of its motion are reflected in mechanics for movements of lesser velocity, and in electro-magnetism—for movements of greater velocity. “Extended, solid, indestructible atoms have always been the stronghold of materialistic views of the universe. But, unhappily for such views, the hard, extended atom was not equal to the demands which increasing knowledge made upon it” (p. 144). The destructibility of the atom, its inexhaustibility, the mutability of all the forms of matter and the variability of its motion, have been the stronghold of dialectic materialism. All boundaries in nature are arbitrary, relative, moveable, and express the gradual approximation of our reason toward the knowledge of matter. But this does not at all prove that nature, matter itself, is a symbol,—a product of our reason. The electron is to the atom as a dot in a book to the size of a building 160 feet long, 80 feet broad, and 40 feet high; it moves with a velocity of 270,000 kilometres per second, its mass is a function of its velocity, it makes 500 trillion rotations in a second—all this is much more complicated than the old mechanics, but all this is, nevertheless, movement of matter in space and time. Human reason has discovered many amazing things in nature and will discover even more, thereby increasing its power over her. But this does not mean that nature is the creation of our reason or of abstract reason, of Ward’s God, or of Bogdanov’s “substitution,” etc.

“Rigorously carried out as a theory of the real world, that ideal lands us in nihilism: All changes are motions, for motions are the only changes we can understand, and so what moves, to be understood, must itself be motion [p. 166]. . As I have tried to show, and as I believe, the very advance of physics is proving the most effectual cure for this ignorant faith in matter and motion as the inmost substance rather than the most abstract symbols of the sum of existence. . . . We can never get to God through a mere mechanism . . .” (p. 180).

Well, this is exactly after the manner of the Outlines of the Philosophy of Marxism! You should now turn, Mr. Ward, to Lunacharsky, Yushkevich, Bazarov and Bogdanov; though they are more “shamefaced” than you, yet they preach the same doctrine.

In 1896, with an air of unusual exultant triumph, the eminent Kantian-idealist, Herman Cohen, came out with an introduction to the fifth edition of the History of Materialism, falsified by Albert Lange. “Theoretical idealism,” exclaimed Cohen (p. xxvi), “has begun to shake the foundations of naturalistic materialism and will, perhaps, soon destroy it. . . . Idealism permeates the new physics. . . . Atomism must give up its place to dynamism. . . . The remarkable turning point set in with a greater realisation of the nature of the chemical problems of substance, enabling them to conquer the materialist views of matter. Just as Thales made the first abstraction of matter and linked to it speculative reflections which later developed into the notion of electrons, so the theory of electricity in turn was destined to cause the greatest revolution in the concept of matter and, through the consequent transformation of matter into force, led to the victory of idealism” (p. xxix).

Herman Cohen, in as clear and definite a manner as James Ward, takes account of the basic philosophic tendencies, without losing himself (as our Machians do) in petty differences between the various kinds of energetic, symbolic, empirio-critical, empirio-monistic, etc., idealisms. Cohen takes the basic philosophic tendency of that school in physics which is now associated with the names of Mach, Poincaré and others, and correctly regards it idealistic. “The transformation of matter into force” appears to Cohen to be the chief gain of idealism, just as it appeared to those “spiritualistic” scientists—whom Dietzgen exposed in 1869. Electricity is declared to be the scientific prop of idealism, for it has destroyed the old theory of the structure of matter, broken up the atom into its elements, discovered new forms of material movement, so unlike the old, so totally beyond anything that had hitherto been investigated or studied, so unusual and “miraculous,” that one could find justification for giving an illegitimate interpretation of nature as immaterial (spiritual, mental, or psychical) motion. The limit of yesterday’s knowledge of the infinitely small particles of matter has disappeared—hence, concludes the idealist, matter has disappeared (and thought remains). Every physicist and every engineer knows that electricity is (material) motion, but nobody can reasonably explain what it is that is being moved; hence, concludes the idealist, we can dupe the philosophically uneducated with the tempting “economical” proposition: “Let us conceive of motion without matter.”

Herman Cohen tries to enlist as his ally the famous physicist Heinrich Hertz. Hertz is ours—he is a Kantian, he sometimes admits a priori reasoning, he says. Hertz is ours—he is a Machian, contends the Machian, Kleinpeter, on the other hand, for in Hertz we find “the same subjective view of conceptions, as we find in Mach.” This curious contention as to whom Hertz belongs is a good example of how resolutely the idealists hunt for the minutest error, the slightest vagueness in the expression of renowned naturalists, in order to justify their renewed defence of fideism. Indeed Hertz’s philosophic preface to his Mechanics reveals the familiar views of the scientists, who have been intimidated by the professorial howl against the “metaphysics” of materialism, but shows nevertheless that Hertz was unable to overcome an instinctive conviction in the reality of the external world. Kleinpeter himself recognises this; Kleinpeter, who on the one hand writes lying popular booklets for masses of readers on the theory of knowledge of the natural sciences, in which Mach is identified with Hertz, while on the other hand, in special philosophic articles, he admits that “Hertz, as distinguished from Mach and Pearson, still clings to the prejudice that it is possible to explain all of physics in a mechanistic way”; that he still retains the conception of the thing-in-itself and “the ordinary viewpoint of physicists,” that Hertz “still adheres to the view of the existence of the world in itself.”

It is interesting to note Hertz’s own attitude toward the theory of energetics. He writes: “If we ask ourselves the real reasons why physics at the present time prefers to express itself in terms of energy, our answer will be that in this way, it best avoids talking about things of which it knows very little. . . . It is true that we are now convinced that ponderable matter consists of atoms; and we have definite notions of the magnitude of these atoms and of their motions in certain cases. But the form of the atoms, their connection, their motions in most cases—all these are entirely hidden from us. . . . So that although our conceptions of atoms is in itself an important and interesting object for further investigations, it is in no wise specially fit to serve as a known and secure foundation for mathematical theories” (p. 21). Hertz, from further study of ether, expects a clarification of the “essence of traditional matter, its inertia and gravitational force” (Vol. I, p. 354).

It is evident from this that Hertz did not even conceive of the possibility of a non-material aspect of energy. For philosophers, energetics served as an excuse to substitute idealism for materialism. The scientist looked upon energetics as a convenient method of expressing the laws of matter in motion at a time when physicists, if the expression is permissible, had set out from the atom, but had not yet reached the electron. This state of affairs has continued to a great extent to the very present; one hypothesis is replaced by another; nothing definite is known of the positive electron. But three months ago (June 22, 1908), Jean Becquerel reported to the French Academy of Science that he had succeeded in discovering this “new component part of matter.” Of course, the idealists simply couldn’t miss the opportunity of making out “matter” to be merely something sought for by the human mind, for then it would really be no more than a “symbol.”

Edward von Hartmann, another German idealist of a more reactionary tinge than Cohen, devoted a whole book to the cosmic outlook of recent physics. We are, to be sure, not interested in the special discussions of the author in defence of his peculiar variety of idealism. Suffice it to say that this idealist states the facts substantially as they had been stated by Rey, Ward and Cohen. “Modern physics has grown on a realistic basis,” says Hartmann, “and only the Neo-Kantian and agnostic movement of our own time has caused the final results of physics to be interpreted in an idealist sense” (p. 218). Three epistemological systems, according to Hartmann, lie at the basis of recent physics—hylo-kinetics (from the Greek hyle-matter, and kinesis-motion, that is, the recognition of physical phenomena through matter in motion), energetics, and dynamism (the recognition of force without substance). It is to be understood that the idealist Hartmann defends “dynamism,” and infers from this that the laws of nature are an expression of the “world-reason”; in a word, he “substitutes psychical for physical nature. But he is forced to admit that hylo-kinetics has most physicists on its side, that this system “is more frequently employed (p. 190), that its serious defect is the “materialism and atheism which menace pure hylo-kinetics” (p. 189). The author quite justly regards energetics as an intermediary system and calls it agnosticism (p. 136). Of course, it is an “ally of pure dynamism, for it eliminates substance” (pp. vi, 92), but Hartmann dislikes its agnosticism, for he believes that it is a form of “anglomania,” incompatible with the essential idealism of a Junker.

It is highly instructive to see how this irreconcilable partisan of idealism (non-partisans in philosophy are just as hopelessly muddleheaded as they are in politics) explains to the physicists what it means to follow one epistemological tendency or another.

“A very insignificant proportion of those physicists who follow this manner,” writes Hartmann of the idealist interpretations of the latest results in physics, “wholly recognise the vast importance and the complete consequences of such an interpretation. They have failed to realize that physics has retained its independence so far as its particular laws are concerned, just as the physicists, despite their idealism, have retained their realistic postulates, e. g., the existence of things-in-themselves, their real mutability in time, real causality. . . . For only by granting these realistic postulates [i. e., the transcendental realistic interpretation of causality, time, three-dimensional space], i. e., on the condition that nature, of whose laws the physicists speak, coincides with the realm of things-in-themselves . . . can one speak at all of natural laws as distinct from psychical laws. Only on the assumption that natural laws act in a realm independent of the realm of our reason, can they serve as an explanation of the fact that the logically necessary consequences of our images prove to be images of the naturally and historically necessary effects of the unknown which these images reflect or symbolise in our consciousness” (pp. 218-219).

Hartmann rightly feels that the idealism of the new physics is only a fashion and not a serious philosophic turning point from natural-historical materialism. He correctly explains to the physicists, therefore, that in order to transform their “fashion” into a consistent, genuine idealism it is necessary to change radically their doctrines of the objective reality of time, space, causality and natural laws. We cannot regard atoms, electrons and ether alone as mere symbols, as mere “working hypotheses,” it is essential to declare time, space, the laws of nature and the whole of the outer world “working hypotheses” as well. Either materialism, or a universal substitution of the psychical for the physical—there is a host of candidates “to mix the two drinks,” but neither we nor Bogdanov belong to that class.

Ludwig Boltzmann was among the foremost of the German physicists who systematically combated the Machian tendency (he died in 1906). We have already pointed out that to the “fad of the new epistemological dogmas” he contrasted the simple and clear reduction of Machism to solipsism (see Chap. I, §6). Boltzmann was, of course, afraid to call himself a materialist and even made it plain that he had nothing against the Divine Being. But his theory of knowledge is essentially materialistic, and as is recognised by S. Günther, the historian of natural sciences in the nineteenth century, it is characteristic of the views of the majority of scientists. “We infer,” says Boltzmann, “the existence of all things solely from the impressions which they make on our senses” (p. 29). Theory is an “image” (or copy) of nature, of the external world (p. 77). To those who maintain that matter is only a complex of sense-perceptions, Boltzmann points out that under such conditions other people are only the sensations of the speaking person (p. 168). These “ideologists,” as Boltzmann sometimes calls the idealists, present us with a “subjective picture of the world” (p. 176). The author prefers a “simpler, more objective picture of the universe.” “The idealist compares the judgment that ‘matter exists as well as our sensations,’ with the child’s notion that a stone which gets a beating experiences pain. The realist compares this judgment according to which it is impossible to imagine the emergence of the psychical out of the material or even out of the play of atoms, with the opinion of an uneducated person who maintains that the distance between the sun and the earth cannot amount to twenty million miles, for he cannot conceive of it” (p. 186). Boltzmann does not deny science’s ultimate ideal to present spirit and volition as “complicated actions of parts of matter” (p. 396).

Boltzmann very often contested Ostwald’s energetics from the standpoint of physics, proving that Ostwald can neither reject nor eliminate the formula of kinetic energy (half of the mass multiplied by the square of velocity) and that he turns in a vicious circle, deducing energy from the mass (by accepting the formula of kinetic energy) at the beginning, and afterwards defining mass as energy (pp. 112, 139). On this occasion I recollect Bogdanov’s exposition of Mach in the third book of Empirio-Monism. “In science,” writes Bogdanov, referring to Mach’s Science of Mechanics, “in the equations of mechanics, the conception of matter is reduced to the projected coefficient of mass, whose magnitude, upon an accurate analysis, proves to be a reciprocal of the acceleration of two physical complexes of bodies” (p. 146). Of course, if a certain body will be taken as the unit, then the motion (mechanical) of other bodies can be expressed by the mere relation of acceleration. But “bodies” (matter) do not at all disappear on account of it, do not thereby cease to exist independently of our consciousness. When the entire world will have been reduced to the movement of electrons, it will be possible to eliminate the electrons from all equations, because it will be assumed everywhere, and the correlation of the groups or of aggregates of electrons will be reduced to their mutual acceleration, if the forms of motion prove to be as simple as those in mechanics.

Combating the “phenomenalist” physics of Mach and the others, Boltzmann maintained that “those who propose to eliminate atomism by means of differential equations, cannot see the wood for the trees (p. 144). . . . If we do not wish to entertain any illusions about the significance of the differential equations, . . . there can be no doubt that this picture of the world (represented by differential equations) must necessarily be in essence atomic, i. e., it will be a summary description that in accordance with certain rules, large quantities of objects situated in a three-dimensional manifold will be conceived as changing in time. These things can, of course, be similar or different, unchangeable or changeable” (p. 156). “It is perfectly obvious that phenomenalist physics only cloaks itself in differential equations,” said Boltzmann in his address at the Congress of Scientists at Munich, “but in reality it likewise is derived from atomic units [Einzelwesen]. And as we have to imagine these units as possessing now one property, now another, for different groups of phenomena, there will soon be need of a simpler and more homogeneous atomism [p. 223]. . . . The doctrine of the electron has developed into an atomic theory for the complete science of electricity” (p. 357). The unity of nature is revealed in the “astonishing and far-reaching analogies” between the differential equations, which hold for different domains of phenomena. “By these same equations we can solve problems of hydro-dynamics and express the theory of potentials. The theory of vortices in liquids as well as the theory of friction in gases reveal the most astonishing analogy to the theory of electro-magnetism, etc.” (p. 7). Those who recognise “the theory of universal substitution,” cannot escape the question: Who was able to “substitute” physical nature so homogeneously?

As if in answer to those who are marking themselves off from the “physics of the old school,” Boltzmann relates in detail how certain specialists in “physical chemistry,” have taken an epistemological position contrary to Machism. In 1903 Vaubel, the author, of “one of the best” works on the subject (according to Boltzmann), “takes a definitely hostile attitude to the frequently praised phenomenalist physics” (p. 381). “He tries to present a more concrete and plausible exposition of the nature of atoms and molecules and the forces acting between and within them. The presentation is in conformity with the most recent experiments in this domain [ions, electrons, radium, Zeeman’s effects, etc.] The author adheres strictly to the dualism of matter and energy, having this in common, that they are both different expressions of the law of the conservation of energy. In relation to matter, the author again clings to a dualism between ponderable matter and ether, yet regards the latter in the most rigorous sense, as material” (p. 381). In the second volume of his works (on the theory of electricity) the author from “the very beginning takes the view that the phenomena of electricity are produced by interaction and motion of atomic entities, namely, electrons” (p. 383).

Hence, as far as Germany is concerned, too, we have confirmed what the spiritualist James Ward recognised to be true for England, namely, that the physicists of the realistic school systematise facts and discoveries of the later years, no less successfully than do the physicists of the symbolic school, and that the essential difference between them consists “only” in different epistemological viewpoints.

The idealist philosophy in France seized upon the vacillations of the Machian physics with no less determination. We have already seen how the neo-criticists reacted to Mach’s Science of Mechanics, having from the start noted the idealist character of the roots of his philosophy. The French Machian, Henri Poincaré, had still more success in this respect. Thereupon, the most reactionary idealist philosophers with definite fideistic tendencies immediately seized upon his theory. Le Roy, the representative of this tendency, contends that “the truths of science are purely conditional, are merely symbolic. You are making absurd ‘metaphysical’ claims to the effect that you have knowledge of objective validity. Be logical, then, and agree with us that science has only a practical significance in one domain of human activity and religion has no less a real significance in another domain of activity. The ‘symbolic’ Machian science has no right to deny theology.” Poincaré felt ashamed of these conclusions, and in his book, The Value of Science, he especially attacked them. But it is worthy to note what sort of an epistemological position he was compelled to take in order to rid himself of allies of Le Roy’s type. He writes: “He [Le Roy] regards the intellect as incurably powerless, it is only able to give more scope to other sources of knowledge, to the heart for instance, to sentiment, to instinct or to faith [p. 113]. . . . I do not go so far as to say that scientific laws are purely conditional, merely symbolic. . . . If, therefore, scientific ‘recipes’ have a value, as rules of action, it is because we know they have succeeded, in general, at least. But to know this is to know something; then why say that we can know nothing” (p. 114)?

Poincaré resorts to the criterion of practice. But thereby he only shifts the question without settling it, for this criterion may be interpreted in a subjective and objective sense. Le Roy also recognises this criterion for the science of commerce; he only denies that it is adequate to serve as a criterion of objective truth. Such a denial is for him sufficient to pave the way to a recognition of the subjective truth of religion existing alongside of the subjective truth (i. e., dependent upon man) of science. Poincaré understood that the reference to practice as an argument against Le Roy would not suffice, and he proceeds with the question of the objectivity of science. “What is the measure of their objectivity? Well, it is precisely the same as for our belief in external objects. These latter are real in that the sensations they make us feel appear to us as united to each other by I know not what indestructible cement and not by the hazard of the day” (p. 139).

That the author of such a remark may be a great physicist is very probable. But it is indisputable that only the Voroshilovs-Yushkeviches can take him seriously as a philosopher.

Materialism is declared destroyed in the name of a “theory” which at the first attack of fideism saves itself under the wing of materialism! For the assumption that sensations are produced in us by real objects and that “faith” in the objectivity of science is equivalent to “faith” in the objective existence of the external objects, is the purest materialism.

“, .. It may be said, for instance, that ether is no less real than any external body” (p. 139).

What a howl our Machians would have raised, had a materialist said that! How many stale witticisms would have been passed regarding “ethereal materialism.” But the founder of recent empirio-symbolism declares a few pages farther on that “what is not thought is pure nothingness, since we can think only thought” (p. 142). You are mistaken, M. Poincaré; the reception your works have received proves that there are people who can give thought to absurdity. To that class belongs the notorious muddlehead, Georges Sorel, who maintains that the “first two parts” of Poincaré’s book on the value of science have been written in the “spirit of Le Roy” and that therefore the two philosophers can be “reconciled” as follows: The attempt to establish the identity between science and the world is an illusion; we must not ask the question whether science can conceive nature or not, for the correspondence between science and the mechanism created by us is quite sufficient.

But if it suffices only to take account of Poincaré’s philosophy and go on from there, it is quite imperative, however, to pause on Rey’s works. We have already pointed out that the two basic tendencies in modern physics, which Rey calls the “conceptual” and “neo-mechanistic,” may be reduced to the distinction between idealist and materialist epistemology. We shall see how the positivist Rey solves the problem in a manner different from the method which the spiritualist Ward, and the idealists Cohen and Hartmann followed, that is, not by seizing upon the philosophic mistakes of the recent physics, and its deviation towards idealism, but by rectifying these errors, and by proving the illegitimacy of the idealist (and fideist) inferences from recent physics.

There is to be found in all of Rey’s works recognition of the fact that the recent “conceptualist” (Machian) theory of physics has been seized upon by fideism (pp. 11, 17, 220, 362 ff), philosophical idealism (p. 200), scepticism with its doubt concerning the rights of reason and the rights of science (pp. 210, 220), subjectivism (p. 311), etc. Therefore as the central problem of his works Rey quite justly takes the “opinions of the physicists as to the objective validity of physics” (p. 3). And what are the results of this analysis?

We shall begin with the basic concept, that of experience. Rey assures us that the subjective interpretation of Mach (let us for the sake of simplicity and brevity take Mach as the representative of the school which Rey terms conceptualist) is a total misunderstanding of his true views. Among the “outstanding features of the philosophy of the end of the nineteenth century” will be found an “empiricism which, having grown subtler and richer in its various shades, has finally led to fideism, to the supremacy of faith—which was once upon a time the great weapon of scepticism against the assertions of metaphysics. Did not this come about because of the fact that little by little, by means of hardly perceptible shadings in the meanings of the words, they deviated from the real meaning of ‘experience’? Indeed, experience, if taken in its conditions of existence, in that experimental science which makes it more exact and refined, leads us to necessity and to truth” (p. 398). It is beyond doubt that Machism, in the broad sense of the word, is nothing but a perversion, by means of imperceptible shadings, of the real sense of the word “experience”! But does Rey, who accuses only the fideists of perversion, but not Mach himself, correct this perversion? Here we have it: “Experience is by definition the cognition of the object. In physical science this definition is more in place than it is elsewhere. . . . Experience is that which our spirit does not command, that which our desires, our volition, cannot change, that which is given and which we do not make ourselves. Experience is the object ‘in front of’ [en face du] the subject” (p. 314).

This is an example of the defence of Machism by Rey! How ingeniously perspicacious was Engels, who characterised the recent type of adherents of philosophic agnosticism and phenomenalism by the expression “shamefaced materialists.” Rey, the positivist and ardent phenomenalist, is a superb example of this type. If experience means the “cognition of the object,” if “experience means the object before the subject,” if experience means that “something external exists and necessarily exists,” it evidently reduces itself to materialism! Rey’s phenomenalism, his emphatic and ardent assertion that nothing is given except sensations, his statement that the objective is equivalent to what has a common significance, etc., etc.—all this is only a figleaf, an empty verbal shield of materialism, since we are told that “the objective is that which is given us from the outside, which is imposed upon us by experience; it is that which we do not make but which is made independently of us and which largely makes us” (p. 320). Rey, in defending “conceptualism,” destroys it! The refutation of the idealist implications of Machism has been reached only by interpreting Machism as a “shamefaced materialism.” Having recognised the distinctions between various tendencies in modern physics, Rey labours hard to do away with all distinctions allegedly in the interests of materialism. Of the school of neo-mechanism, for instance, Rey says that it does not admit the “least doubt, the least uncertainty” as to the objectivity of physics (p. 237): “Here [on the basis of the doctrines of this school] you feel far removed from all the circuitous routes you were compelled to traverse from the point of view of other conceptions of physics in order to arrive at the position of this objectivity” (p. 237).

It is this “circuitous route” of Machism which Rey conceals, over which he throws a veil in all of his expositions. The fundamental characteristic of materialism lies in that it arises from the objectivity of science, from the recognition of objective reality, reflected by science, while idealism needs these “circuitous” methods in order to “infer” the objectivity of nature, in one way or another, from spirit or consciousness, from the “psychic.” “The neo-mechanists, the prevailing school in physics, believe in the reality of the external world” (p. 234). For this school, “theory wishes to be an analogue [le decalque] of the object” (p. 235). True. And this fundamental basis of the “neo-mechanist” school is nothing but the foundation of the materialist theory of knowledge. No renunciation of materialism by Rey, no assurances that the neo-mechanists are also phenomenalists, can mitigate this basic fact. The difference between the neo-mechanists (materialists, who are more or less shamefaced) and the Machians is that the latter deviate more strongly from this theory of knowledge, and inevitably succumb to fideism.

Take the relation of Rey to Mach’s doctrines on causality and necessity in nature. Only at first sight, Rey assures us, does it appear that Mach is “approaching towards scepticism” and “subjectivism” (p. 76); this “ambiguity” (p. 115) disappears if we take the view of Mach as a whole. And Rey, taking it as a whole, adduces a series of quotations from the Wärmelehre and the Analysis of Sensations, and pauses especially on the chapter devoted to causality in the former book, but is cautious enough to refrain from citing the most decisive remark of all, the declaration of Mach that there is no physical necessity; but only a logical necessity! To such a method of exposition we can only say that it is not an interpretation of Mach, but an embellishment upon him; that it is an obliteration of the differences between “neo-mechanism” and Machism. Rey’s conclusion is that “Mach continues the analysis and accepts the findings of Hume, Mill and all the other phenomenalists, according to whom the causal relation has no substantiality but is only a mental habit. He accepts the fundamental thesis of phenomenalism from which only one consequence follows—that nothing exists save sensations. But Mach adds as a purely objective modification that “science, analysing sensations, discovers their permanent and common elements which, being abstractions, have the same reality as the sensations themselves, for they are taken from sensations by means of perceptual observation. And these common and permanent elements such as energy and its various forms, are the foundations for the systematisation of physics” (loc. cit., p. 117).

This means that Mach accepts Hume’s subjective theory of causality and interprets it in an objective sense! Rey evades the task of defending Mach by referring to his inconsistency, and reducing it to something like the following: In the “real” interpretation of experience, we are led to “necessity.” If experience is what is given to us from the outside, and if the necessity of nature and its laws are also given to man from the outside or from objectively existing nature, then it is obvious that the difference between Machism and materialism vanishes. Rey defends Machism against “neo-mechanism” in such a fashion that it capitulates along the entire line to the latter. The word “phenomenalism” is retained and defended but not the substance of the doctrine. Poincaré, for instance, in the spirit of Mach, derives the laws of nature including the tri-dimensionality of space; but this is done on grounds of “convenience.” But this does not at all leave any place for “indetermination,” Rey hastens to “correct” us. Nay, “convenient” here means “adaptation to the object” (Rey’s italics, p. 196). Indeed, what a superb differentiation between the two schools! What a “refutation” of materialism! . . . “If Poincaré’s theory logically separates itself by an impassable gulf from the ontological interpretation of mechanism [that is, from the doctrine that theory is a copy of the object] . . . if it is to serve as a support for philosophic idealism, then at least, on scientific grounds, it must be compatible with the general evolution of classical ideas, with the tendency which regards physics as objective knowledge, as objective as experience, that is, as the sensations out of which experience is built up” (p. 200).

On the one hand, we must admit; on the other hand, we must confess. On the one hand, an impassable gulf separates Poincaré from neo-mechanism, although Poincaré stands in between Mach’s conceptualism and neo-mechanism, so that it turns out that Mach is not separated by an impassable gulf from neo-mechanism. On the other hand, according to Rey himself who holds the viewpoint of “mechanism,” Poincaré fully agrees with classical physics. On the one hand, the theory of Poincaré is capable of serving as a support to philosophic idealism; on the other hand, it is compatible with the objective interpretation of the word “experience.” On the one hand, these bad fideists perverted the meaning of experience by the aid of expressions which imperceptibly deviated from the correct view that “experience is the object”; on the other hand, the objectivity of experience means only that experience is sensation, a statement with which both Berkeley and Fichte agree!

Rey blundered because he set himself the impossible task of “reconciling” the opposition between the materialist and the idealist schools in recent physics. He set out to subvert the materialism of the neo-mechanist school, having already attempted to reduce the views of physicists, who regard their theory as a copy of the object, to phenomenalism.

Rey also attempts to tone down the idealism of the conceptualist school by eliminating the most emphatic idealistic declarations of its adherents and interpreting the rest from the point of view of a shamefaced materialism. Rey’s estimate, for example, of the theoretical significance of the differential equations of Maxwell and Hertz shows to what extent his repudiation of materialism is fraudulent and fictitious. For the Machians the circumstance that these physicists limit their theory to a system of equations, is a refutation of materialism—there are only equations, there is no matter, no objective reality, only symbols. Boltzmann refutes this view, quite aware of the fact that he is refuting phenomenalist physics. Rey refutes this view in an intended defence of phenomenalism. He says: “We cannot refuse to regard Maxwell and Hertz as ‘mechanists’ merely because they limited themselves to equations, similar to the differential equations of Lagrange’s dynamics. The equations do not prevent us, according to Maxwell and Hertz, from constructing a mechanical theory of electricity out of real elements. On the contrary, the fact that we can represent electrical phenomena in a theory whose form is identical with the general form of classical mechanics, is proof of the possibility” (pp. 252-3). The indefiniteness of the present state of the problem will in a measure diminish when the nature of these quantities which enter as elements in the equations will have become more precise (p. 253). Failure to investigate these and other forms of material motion is not taken by Rey as a reason for denying the materiality of motion. “The homogeneity of matter” is regarded (p. 262), not as a postulate, but as a result of experience and evolution of science; “the homogeneity of the object of physics” appears as the condition of the possibility of measurement and mathematical calculation.

Here is Rey’s estimate of the criterion of practice in the theory of knowledge: “Contrary to the postulates of scepticism, we have a right to say that the practical validity of science is derived from its theoretical validity” (p. 368). That this sceptical attitude is unequivocally accepted by Mach, Poincaré and their entire school—of this Rey prefers not to speak. . . . “Theoretical and practical validity are two inseparable and strictly parallel aspects of objective validity. To say that a law of nature has practical validity . . . is to say that it has an objective significance. . . . To act on an object implies a modification of the object, implies a reaction upon the part of the object which conforms to the expectations of predictions, which are contained in the proposition and in virtue of which we acted on the object.

“Hence, these expectations or this anticipation contain elements controlled by the object and our action. . . . In these diverse theories there is thus an objective part” (p. 368). This is materialism through and through! All other theories of knowledge, especially Machism, deny the objective, deny that the criterion of practice does not depend upon man and mankind.

The result is this: Although Rey did not approach the question from the same angle as did Ward, Cohen and the others, he arrived at the same results, namely, the recognition that at the basis of the division between the two chief schools in modern physics lay the difference between the materialistic and idealistic points of view.

Due to certain deplorable conditions under which I have been compelled to work, I have been almost unable to acquaint myself with the Russian literature on the subject. I will, therefore, confine myself to an examination of a very important article by the notorious philosophic member of the “black-hundred,” Mr. Lopatin. This “true-Russian” philosophic idealist is related to the contemporary European idealists as, for example, the “Union of the Russian People” is related to the western reactionary parties. Still more instructive is it to see how similar homogeneous philosophic tendencies manifest themselves in surroundings, quite different in their general culture and mode of life. Lopatin’s article is, as the French say, an éloge—a eulogy—to the Russian physicist Shishkin, who died in 1906. Mr. Lopatin was impressed by the fact that this educated man who took such an interest in Hertz and the new physics in general was not only a right-wing Constitutional Democrat, but a strong believer in, and adherent of, the philosophy of Vladimir Soloviov, and so forth, and so on (p. 339). However, in spite of his pre-eminent “inclination” towards an interest which lies somewhere between the department of philosophy and the department of police, Mr. Lopatin has presented some material towards the characterisation of the epistemologic views of the idealist-physicist. He writes: “He was a real positivist in his tireless and resolute criticism of the validity of the methods of scientific investigation, and of both its customary assumptions and facts, in order to discover the means and material for the construction of a complete world view. In this respect Shishkin was the antipodes of many of his contemporaries. In those articles of mine which have previously appeared in this periodical, I have often tried to reveal the heterogeneous and frequently inconsistent elements out of which a scientific view is built up. In it there enter established facts and more or less brave generalisations, which have proved convenient at the moment in one scientific domain or another, hypotheses and purely auxiliary scientific fictions. And all this is elevated to the high office of serving as incontrovertible objective truth, from whose viewpoint all other ideas and all other beliefs of a philosophic and religious nature must be judged and rejected in so far as they do not conform to what these alleged truths express. Our extremely talented thinker, the materialist Professor V. I. Vernadsky, has shown with exemplary clarity how shallow and improper are these pretences which claim to have demonstrated the scientific views of a given historical epoch to be an immobile, dogmatic system obligatory for all. Whilst the wide circles of the reading public are guilty of such a belief [Lopatin’s note: “For these circles a series of popular books has been written, whose mission it is to serve as a scientific catechism for definitely answering all questions. The typical work is Force and Matter by Büchner, or Haeckel’s The Riddle of the Universe], and with them also individual scientists of special branches of natural science, it is even more strange that the official philosophers themselves are guilty; for all their efforts are directed to prove that they say nothing except what has already been said before by the representatives of the several sciences, and that they are merely expressing it in their own language.

“Shishkin had no dogmatic prejudices. He was an ardent champion of a mechanical explanation in the realm of natural phenomena, but for him it was only a method of investigation.”

Well, well, these are quite familiar strains! “He did not at all assume that the mechanical theory revealed the very essence of the phenomena investigated; he saw in it only the most convenient and fundamental productive method for unifying the sciences, and serving as the instrument in the realisation of scientific aims. For him, therefore, the mechanical conception of nature and the materialistic interpretation do not at all coincide. . . .” Exactly as in the case of the authors of the Outlines of the Marxian Philosophy! “. . . On the contrary, he held that on questions of a higher kind, the mechanical theory ought to take a very cautious and conciliatory attitude.”

In the language of the Machians this is called “transcending the obsolete and one-sided” distinction between materialism and idealism. “. . . Questions of the origin and the end of things, of the inner being of our spirit, of the freedom of the will or immortality of the soul, etc., cannot, in the actual depths of their meaning, fall within the purview of the mechanical theory—since as a method of investigation, it is confined to the limits of natural applicability, to the facts of physical experience only . . .” (p. 342). The last two lines are surely a plagiarism from Bogdanov’s Empirio-Monism.

“Light can be regarded,” wrote Shishkin in his article, “as substance, as motion, as electricity, as sensation.”

It is almost certain that Lopatin is right in linking Shishkin up with the positivists and that he wholly belonged to the Machian school of recent physics. Shishkin, in his lecture on light, states in effect that the various methods of approach to the nature of light constitute various methods of “organising experience” (according to Bogdanov’s terminology), equally legitimate from different points of view; or that they represent various “connections of elements” (according to Mach’s terminology), and that the doctrines of the physicists at any rate do not regard the theories of light as a copy of objective reality. But Shishkin argued very badly. “Light can be regarded as substance, as motion . . .” he says. But in nature there is no substance without motion and no motion without substance. The first “distinction” of Shishkin’s is absurd. “As electricity. . . .” Electricity is motion of some sort of substance, hence, here also is Shishkin wrong. The electro-magnetic theory of light showed that light and electricity are forms of motion of one and the same substance (ether). “As sensation . . .” he winds up. Sensation is the image of moving matter. Save through sensations, we cannot know of the existence of forms of substance, or of forms of motion; sensations are produced by the effect of matter in motion upon our sense-organs. That is how natural science views it! The sensation of red reflects ether vibrations whose frequency approximately amounts to 450 trillions per second. The sensation of blue reflects ether vibrations whose frequency is approximately 620 trillions per second. The vibrations of the ether exist independently of our visual sensations. Our visual sensations depend upon the effects of the vibrations of ether upon our organs of vision. Our sensations reflect objective reality, something which exists independently of humanity and human sensations. That is how natural science views it! Shishkin’s lecture, aimed against the materialists, is the cheapest sophistry.

We have seen that the epistemological questions raised by recent physics have been discussed from various aspects, in English, German and French literature. There can be no doubt that we have before us a certain international ideological movement, which does not depend upon one philosophic system or another as such, but which is the result of certain general causes, lying outside of philosophy proper. Examination undoubtedly reveals that Machism is “connected” with modern physics, but reveals also at the same time that the conception of this connection broadcasted by our Machians is fundamentally incorrect. As in philosophy, so in physics, the Machians slavishly follow the fashion, and are unable to give a general survey and evaluation of the well-known contemporary tendencies in physics from their own allegedly Marxian standpoint.

All the harangue about Mach’s philosophy being a “philosophy of twentieth century natural science,” of “recent scientific positivism,” etc., (Bogdanov in the preface to Analysis of Sensations, pp. iv, xii; cf. Yushkevich, Valentinov, et al.), is characterised by a twofold misconception. In the first place, Machism is ideologically connected with only one school of modern science. Secondly, and this is the chief thing: not what separates Machism from all other tendencies and puppet systems of idealist philosophy, but what it has in common with idealism in general, is the element which connects Machism with this school. It suffices merely to cast a glance at the ideologic movement in question, as a whole, in order to grasp the truth of this statement beyond the shadow of any doubt. Take the physicists of this school, the German, Mach, the Frenchman, Henri Poincaré, the Belgian, Duhem, the Englishman, Pearson. There is much in common among them; they have the same basis and the same direction, as each of them justly acknowledges. But neither the doctrine of empirio-criticism in general, nor Mach’s belief in the “elements of the world,” in particular, enter into this common basis. These views are quite foreign to the three latter physicists. The “only” thing they have in common is—philosophical idealism towards which they all, without exception, tend more or less consciously, more or less definitely. Turn to the philosophers who base their own doctrines upon this school of modern physics, who try to lay its epistemological foundations and develop its implications, and you will here again see the immanentists, the disciples of Mach, the French neo-criticists and idealists, the English spiritualists, the Russian Lopatin, in addition to the sole empirio-monist Bogdanov. They have only one thing in common, that is, all of them espouse idealism, more or less consciously, more or less definitely, be it with a rapid and eager shift towards its latent fideism, be it with a personal aversion towards it (as in Bogdanov’s case).

The basic idea of the school of recent physics which we have analysed is either a denial or doubt of the objective reality given to us in our sensation and reflected in our scientific theories. Here this school departs from materialism (incorrectly named realism, neo-mechanism, hylo-kinetism, none of which have been consciously developed by the physicists), from the philosophy which as generally recognised, prevails among the physicists. It takes its point of departure, then, as a school of “idealistic physics.”

To explain this queer term, it is necessary to recall one episode in the history of recent philosophy and recent science. In 1866 Feuerbach attacked Johannes Müller, the famous founder of modern physiology, and ranked him with the “physiologic idealists.” The idealism of this physiologist consisted in the fact that while investigating the significance of the mechanism of our sense-organs in their relation to sensations, showing, for instance, that the sensation of light is produced by a specific kind of energy affecting the eye, he was inclined to conclude therefrom that our sensations were not images of objective reality. Feuerbach very aptly characterised this as a tendency towards “physiological idealism,” towards an idealist interpretation of certain findings in physiology. The “connection” between physiology and idealism, chiefly of the Kantian kind, had for a long time been exploited by the reactionary philosophy. Lange utilised these physiological data in the interests of Kantian idealism in order to refute materialism. And among the immanentists (whom Bogdanov incorrectly classifies as holding a position in between Mach and Kant), Rehmke especially came out in 1882 against the fictitious claims made by Kantianism regarding the supposed confirmatory evidence of physiology. That a host of eminent physiologists at that time betrayed inclinations towards idealism and Kantianism, is as indisputable a fact as that a host of eminent physicists to-day gravitate towards idealism. “Physical” idealism, that is, the idealism of a certain school of physicists at the end of the nineteenth and the beginning of the twentieth century, no more “refutes” materialism, no more establishes the connection between idealism—or empirio-criticism—and natural science, than did Lange and the “physiological” idealists. This deviation towards reactionary philosophy, which was manifested on occasions, by one school of scientists, in one branch of science, is a temporary relapse, in a sickly period in the history of science,—is the effect of growing pains brought on by a sharp crisis in old established ideas.

The connection between modern “physical” idealism and the crisis of modern physics, as we have already pointed out above, is generally acknowledged on all sides. “The sceptical arguments, directed against modern physics,” writes Rey, having in mind not so much the sceptics as the outspoken adherents of fideism, like Brunetière, “can be essentially reduced to the proverbial argument of all sceptics—to the differences of opinion [amongst the physicists].” But these differences “do not militate against the objectivity of physics. In the history of physics as in any other history one can distinguish great periods which are characterised by a certain aspect and general form of its theories. . . . When a discovery is made which affects all fields of physics, which establishes some cardinal fact hitherto unknown or unappreciated, the entire aspect of physics is changed; a new period commences. So it was after Newton’s discovery, so it was after the discoveries of Joule-Meyer and Carnot-Clausius. . . . The same result, apparently, has followed upon the discovery of radio-activity. . . . The historian who can observe events with the requisite aloofness, will without difficulty discern a continuity of evolution where our contemporaries see only conflicts, contradictions, and divisions into various schools. It seems that the crisis which physics has recently experienced belongs to the same category (despite the conclusions which have been drawn from this crisis by philosophical criticism). This is a typical crisis in its natural growth occasioned by great new discoveries. It is almost certain that the crisis will lead to the modification of physics; without it there could be no evolution and no progress, but it certainly will not change the scientific spirit” (pp. 370-372).

Rey, the conciliator, tries to unite all schools of modern physics against fideism! This mistake is well meant, but it is a mistake none the less, for the deviation of the school of Mach-Poincaré-Pearson towards idealism (which is but a refined fideism) is beyond dispute. And this objectivity of physics, which is at the basis of the “scientific spirit,” and which Rey defends so ardently, as opposed to the spirit of fideism, is nothing but a “shamefaced” formulation of materialism. The basic materialistic spirit of physics, as of the whole of modern science, will overcome all sorts of crises, provided the necessary change from metaphysical materialism to dialectical materialism takes place.

Rey, the peacemaker, very often silently glides over the fact that the crisis of modern physics lies in its deviation from a direct, decisive and definite recognition of the objective validity of its theories. But the facts are stronger than all his conciliatory efforts. “The mathematicians,” writes Rey, “who are accustomed to deal with a science in which the object, at least on the surface, is created by the mind of the scientist or in which, at any rate, concrete appearances are not admitted into investigations, have given expression to an abstract conception of physics, and have tended to reduce it to mathematics, by applying the general theory of mathematics to physics. . . . All the experimenters have denounced the invasion of the mathematical spirit into the methods of judging and understanding physics. And is it not due to this influence, which is none the less powerful for being concealed, that the uncertainty, the hesitation of thought regarding the objectivity of physics is to be attributed, together with those circuitous ways by which objectivity is reached and the obstacles which are surmounted in order to prove it. . . ?” (p. 227).

This is very well said. “Hesitation of thought” in the question of the objectivity of physics—here lies the substance of fashionable “idealistic physics.”

“. . . The abstract fictions of mathematics seem as if they erected a screen between physical reality and the manner in which the mathematicians understand this science. They vaguely feel the objectivity of physics . . . they desire before anything else to be objective when they engage in physics; they endeavour to lean upon reality, but their old habits assert themselves. And so in the course of recent scientific theory up to and including energetics—which desired to construct the world with a fewer number of hypotheses than the old mechanical physics, which was satisfied to copy the perceptual world, and not to re-create it—we constantly have had to deal with the theories of mathematicians. . . . The mathematicians have done everything they could to save the objectivity of physics, for without objectivity—they understand this very well—there cannot be any talk about physics. . . . But the complexity of their theories, their circuitous methods have left an uneasy feeling. They are too artificial, too far-fetched, too fictitious; the experimenter does not feel that instinctive confidence in them which is developed through constant contact with physical reality. . . . This is what all the physicists essentially claim, those who are primarily physicists—and those who are exclusively physicists; this is what the entire neo-mechanist school claims. . . . The crisis of physics has been precipitated through the permeation of the mathematical spirit. The progress of physics in the nineteenth century, on the one hand, and the progress of mathematics on the other, led to the close proximity of these two sciences. . . . Theoretical physics became mathematical physics. . . . Then began the period of formal physics, that is, of mathematical physics, which became purely mathematical, not as a branch of physics but as a branch of mathematics. In this new phase the mathematician, accustomed to have the conceptual (purely logical) elements constitute the sole subject matter of his work, found himself cramped before the rough, material elements which he found not sufficiently pliable for formal analysis. He therefore could not avoid abstracting from them as much as possible, was inclined to postulate them as absolutely immaterial as purely logical, or even to ignore them altogether. The elements as real, objective data, i. e., as physical elements, completely vanished. There remained only the formal relations which are represented by differential equations. . . . If the mathematician be not deceived by his own constructive work, he will be able to find the connections between theoretical physics and actual experience, but at first sight it seems to an untutored eye that the entire thing is an arbitrary theoretical construction. . . . The concept, the idea, replaces real elements everywhere. . . . Thus, in virtue of the mathematical form, accepted by theoretical physics . . . the illness, the crisis of physics and its apparent separation from objective facts, are historically explained” (pp. 228-232).

Such is the first cause of “idealistic physics.” The reactionary claims that have been put forward are really the consequences of progress within science. The great success of science, its discovery of the homogeneous and simple elements of matter, whose laws of motion are subject to formulæ, caused matter to be forgotten by the mathematicians. “Matter disappears,” only equations remain. In a new stage of development and, as it were, in a new way, we get the old Kantian idea: reason prescribes laws to nature. Herman Cohen who rejoices, as we have seen, over the idealistic spirit of recent physics, goes so far as to advocate the introduction of higher mathematics into schools in order to implant in the high-school students the spirit of idealism, which is in danger of being extinguished in our materialistic age. Of course this is a ridiculous fancy of a reactionary and, except for the temporary infatuation with idealism by a limited number of specialists, there really is nothing to it, nor can there be anything to it. But what is highly characteristic is how these drowning faiths clutch at a straw, and with what cunning the representatives of the educated bourgeoisie artificially attempt to sustain and find a place for fideism whose hold on the lower strata of the masses is due to ignorance, backwardness, and to the absurd and wild contradictions of capitalist society.

Another cause of “idealistic physics” is the principle of relativity, the relativity of science, a principle which in a period of bankruptcy of old theories, imposes itself with special force upon physicists, and which, due to ignorance of dialectics, leads to idealism.

The question of the correlation between relativism and dialectics is of the utmost importance in explaining the theoretical misfortunes of Machism. Here is Rey, for instance, who, like the rest of the European positivists, has no idea of Marxian dialectics at all. He employs the word dialectics exclusively in the sense of idealist speculation. Feeling, therefore, that the new physics went astray on the question of relativism, he helplessly flounders in an attempt to distinguish between moderate and immoderate relativism. Of course, “immoderate relativism borders on actual scepticism, in theory if not in practice” (p. 215). But, as you see, in Poincaré there is no “immoderate” relativism. One imagines that by adding to the mess, a pinch of relativism weighed on an apothecary’s scale, the position of Machism can be improved!

The only correct way of theoretically positing the question of relativism, has been expressed by the dialectic materialism of Marx and Engels. Ignorance of it must certainly lead from relativism to idealism. Failure to understand this fact makes Mr. Berman’s absurd book Dialectics from the Standpoint of The Modern Theory of Knowledge (in Russian) valueless. Mr. Berman repeated the old absurdities about the dialectical philosophy which he completely failed to understand. We have already seen that all the Machians, at each step, manifest similar ignorance of the theory of knowledge.

All the old truths of physics, including those which were regarded as the most firmly established and incontestable, have proven to be relative truths. This means that there is no such thing as objective truth independent of humanity. Thus argue not only the followers of Machism but all adherents of “idealistic physics” in general. That absolute truth results from the sum-total of relative truths in the course of their development; that relative truths represent approximate reflections of an object which exists independent of humanity; that these reflections continually approach the truth; that in each scientific truth, irrespective of its relativity, there is an element of absolute truth—all these propositions, obvious to anyone who has reflected on Engels’ Anti-Dühring, remains for the “modern” theory of knowledge a closed book with seven seals.

Such works as Duhem’s, or Stallo’s, which Mach especially recommends, show very clearly that these “idealistic physicists” ascribe most significance to the hypothesis of the relativity of our sciences, and vacillate for the most part between idealism and dialectical materialism. Both authors, who belong to different periods, and who approach the question from different viewpoints (Duhem’s specialty is physics, in which field he worked for twenty years; Stallo, an erstwhile ardent Hegelian, spurned his own book on natural philosophy [published in 1848], which was conceived in the old Hegelian spirit), combat the atomistic mechanistic conception of nature most energetically. They establish the limitations of such a conception, maintain the impossibility of recognising it as the limit of our knowledge, and point to the ossified and antiquated doctrines of many writers who cling to this conception of physics. This defect in the old materialism is undeniable; its failure to appreciate the relativity of all scientific theories, its ignorance of dialectics, its exaggeration of the mechanistic viewpoint—these were Engels’ reproaches against the earlier materialists. But Engels, unlike Stallo, was able to abandon the Hegelian idealism, and yet retain the kernel of sound insight in Hegel’s dialectics. Engels rejected the old metaphysical materialism for dialectical materialism, and not for a relativism, which plays into the hands of subjectivism. “The mechanical theory,” says Stallo, “in common with all metaphysical theories, hypostasises partial, ideal, and, it may be, purely conventional groups of attributes, or single attributes, and treats them as varieties of objective reality” (p. 150). This is quite true, if you recognise the primary fact of objective reality and are combating metaphysics as opposed to dialectics. Stallo does not make this clear himself. He has no grasp of materialist dialectics and therefore falls from relativism into subjectivism and idealism.

The same with Duhem. At an enormous expenditure of labour, in a series of interesting and valuable examples from the history of physics (a type of study which one frequently encounters in Mach), he proves that “each law of physics is temporary and relative because it is approximate” (p. 280). Well, he is trying to force his way through an open door, reflects the Marxist while reading the lengthy treatises on this subject. But the trouble with Duhem, Stallo, Mach and Poincaré is that they do not see that the door had already been opened by dialectical materialism. Hence unable to give a correct expression to relativism, they relapse into idealism. “The laws of physics, properly speaking, are neither true nor false, but approximate,” writes Duhem (p. 272). In this “but” there already lies the germ of an error. It also marks the beginning of an attempt to eliminate the difference between a scientific theory which approximately reflects the object i. e., approaches objective truth, and arbitrary, phantastic, and purely conventional theories, as, for example, religious doctrines and the systematised rules of chess.

This error goes so far with Duhem that he declares the question, as to whether “material reality” corresponds to perception, to be metaphysics (p. 10). Away with all questions about reality; our ideas and hypotheses are mere signs, “arbitrary” (p. 27) constructions, etc. There is only one step from this to idealism, to the “physics of the believer,” which Pierre Duhem preaches in true Kantian fashion (cf. Rey, p. 162; also p. 160). And the good-natured Adler (Fritz), also a Machian claiming to be a Marxian, had no keener “correction” to offer than this: Duhem eliminates the notion of “realities, hidden beyond appearance, only as objects of theory, but not as real objects.” This is the familiar criticism of Kantianism made from the standpoint of Hume and Berkeley.

Of course, there can be no talk of Duhem’s being a conscious Kantian. He merely vacillates, as does Mach, without knowing how to support his relativism. At many points he comes very close to dialectical materialism. He says that we know sound as “it exists in relation to us but not as it exists in itself, that is, in bodies which cause sound. This reality, of which our sensations disclose only the external, superficial effects, affords the possibility of conceiving a theory of acoustics. They tell us that where our perceptions register the effects which we call sound, there really exists a rapid, periodic, wave movement (p. 7). Bodies are not symbols of sensation, but sensations are symbols (rather images) of bodies. The development of physics gives rise to a constant struggle between nature which continually offers new material; as reason which continually attempts to cognise it” (p. 32); nature is infinite and its smallest particle, the electron, is infinite, and reason is engaged in an infinite transformation of “things-in-themselves” into “things-for-us.” “The struggle between reality and the laws of physics will last infinitely; for each law which physics will formulate, sooner or later reality will produce a rude refutation, in the form of an inexplicable fact; but physics will continually modify, change, and qualify the refuted law” (p. 290). This would be quite an adequate exposition of dialectical materialism, if the author firmly clung to the conception of a reality existing independent of humanity. “. . . The theory of physics is not a purely artificial system, to-day convenient, to-morrow worthless; it is a classification, becoming more and more natural, a reflection growing clearer and clearer, of those realities which the experimental method cannot meet face to face” (p. 445).

Duhem, the Machian, in this last phrase flirts with Kantian idealism; it appears as if a path has been opened up for another method besides an “experimental” one, as if we cannot directly, and immediately perceive “thing-in-themselves” face to face. But if the theory of physics becomes more and more natural, then “nature” and reality, “reflected” by this theory exists independently of our consciousness—which is precisely the view of dialectic materialism.

In a word, the “physical” idealism of to-day, just as the “physiological” idealism of yesterday merely signifies that one school of naturalists in one branch of science have succumbed to reactionary philosophy, without being able to rise directly and immediately above metaphysical materialism and to arrive at dialectic materialism. Modern physics has made and will continue to make this step, but it reaches the only true method and the only true philosophy of natural science, not directly but through zigzag progress, not consciously but instinctively, not clearly aware of its “final goal,” but continually drawing nearer to it, through groping, vacillating, even retrogressive motion. Modern physics is in a state of confinement; it is giving birth to dialectical materialism. The child-birth is painful. Besides a living being, it inevitably brings forth certain dead products, refuse which should be sent where it belongs. To the category of such refuse belong the entire school of “idealistic physics,” the whole of empirio-critical philosophy together with empirio-symbolism, empirio-monism, etc., etc.