Bogdanov made his discovery in 1906, in the preface to Book III of his Empirio-Monism. “Engels in Anti-Dühring,” writes Bogdanov, “expresses himself almost in the same sense in which I have just described the relativity of truth” (p. v)—that is, in the sense of denying all eternal truth, “denying the unconditional objectivity of all truth whatsoever.” “Engels is wrong in his indecision, in the fact that in spite of his irony he recognises certain ‘eternal truths,’ wretched though they may be. . .” (p. viii). “Only inconsistency can here permit such eclectic reservations as those of Engels. . .” (p. ix). Let us cite one instance of Bogdanov’s refutation of Engels’ eclecticism. “Napoleon died on May 5, 1821,” says Engels in Anti-Dühring, in the chapter “Eternal Truths,” where he reminds Dühring of the “platitudes” (Plattheiten) to which he who claims to discover eternal truths in the historical sciences has to confine himself. Bogdanov thus answers Engels: “What sort of ‘truth’ is that? And what is there ‘eternal’ about it? The recording of a single correlation, which perhaps even has no longer any real significance for our generation, cannot serve as a basis for any activity, and leads nowhere” (p. ix). And on page viii: “Can Plattheiten be called Wahrheiten? Are ‘platitudes’ truths? Truth is a vital organising form of experience; it leads us somewhere in our activity and provides a point of support in the struggle of life.”
It is quite clear from these two quotations that Bogdanov, instead of refuting Engels, makes a mere declamation. If you cannot assert that the proposition “Napoleon died on May 5, 1821,” is false or inexact, you acknowledge that it is true. If you do not assert that it may be refuted in the future, you acknowledge this truth to be eternal. But to call phrases such as truth is a “vital organising form of experience” an answer, is to palm off a mere jumble of words as philosophy. Did the earth have the history which is expounded in geology, or was the earth created in seven days? Is one to be allowed to dodge this question by Is one to be allowed to dodge this question by talking about “vital” (’what does that mean?) truth which “leads” somewhere, and the like? Can it be that knowledge of the history of the earth and of the history of humanity “has no real significance”? This is just turgid nonsense, used by Bogdanov to cover his re treat. For it is a retreat, when, having taken it upon himself to prove that the admission of eternal truths by Engels is eclecticism, he dodges the issue by a mere noise and clash of words and leaves unrefuted the fact that Napoleon did die on May 5, 1821, and that to regard this truth as refutable in the future is absurd.
The example given by Engels is elementary, and anybody without the slightest difficulty can think of scores of similar truths that are eternal and absolute and that only insane people can doubt (as Engels says, citing another example: “Paris is in France”). Why does Engels speak here of “platitudes”? Because he refutes and ridicules the dogmatic, metaphysical materialist Dühring, who was incapable of applying dialectics to the relation between absolute and relative truth. To be a materialist is to acknowledge objective truth, which is revealed to us by our sense-organs. To acknowledge objective truth, i.e., truth not dependent upon man and mankind, is, in one Way or another, to recognise absolute truth. And it is this “one way or another” which distinguishes the metaphysical materialist Dühring from the dialectical materialist Engels. On the most complex questions of science in general, and of historical science in particular, Dühring scattered words right and left: ultimate, final and eternal truth. Engels jeered at him. Of course there are eternal truths, Engels said, but it is unwise to use high-sounding words (gewaltige Worte) in connection with simple things. If we want to advance materialism, we must drop this trite play with the words “eternal truth”; we must learn to put, and answer, the question of the relation between absolute and relative truth dialectically. It was on this issue that the fight between Dühring and Engels was waged thirty years ago. And Bogdanov, who managed “not to notice” Engels’ explanation of the problem of absolute and relative truth given in this very same chapter, and who managed to accuse Engels of “eclecticism” for his admission of a proposition which is a truism for all forms of materialism, only once again betrays his utter ignorance of both materialism and dialectics.
“Now we come to the question,” Engels writes in Anti-Dühring, in the beginning of the chapter mentioned (Part I, Chap. IX), “whether any, and if so which, products of human knowledge ever can have sovereign validity and an unconditional claim (Anspruch) to truth” (5th German ed., p. 79). And Engels answers the question thus:
“The sovereignty of thought is realised in a number of extremely unsovereignly-thinking human beings; the knowledge which has an unconditional claim to truth is realised in a number of relative errors; neither the one nor the other [i.e., neither absolutely true knowledge, nor sovereign thought] can be fully realised except through an endless eternity of human existence.
“Here once again we find the same contradiction as we found above, between the character of human thought, necessarily conceived as absolute, and its reality in individual human beings with their extremely limited thought. This is a contradiction which can only be solved in the infinite progression, or what is for us, at least from a practical standpoint, the endless succession, of generations of mankind. In this sense human thought is just as much sovereign as not sovereign, and its capacity for knowledge just as much un limited as limited. It is sovereign and unlimited in its disposition (Anlage), its vocation, its possibilities and its historical ultimate goal; it is not sovereign and it is limited in its individual expression and in its realisation at each particular moment” (p. 81).[Cf. V. Chernov, loc. cit., p. 64, et seq. Chernov, the Machian, fully shares the position of Bogdanov who does not wish to own himself a Machian. The difference is that Bogdanov tries to cover up his disagreement with Engels, to present it as a casual matter, etc., while Chernov feels that it is a question of a struggle against both materialism and dialectics.]
“It is just the same,” Engels continues, “with eternal truths.”
This argument is extremely important for the question of relativism, i.e., the principle of the relativity of our knowledge, which is stressed by all Machians. The Machians one and all insist that they are relativists, but the Russian Machians, while repeating the words of the Germans, are afraid, or unable to propound the question of the relation of relativism to dialectics clearly and straightforwardly. For Bogdanov (as for all the Machians) recognition of the relativity of our knowledge excludes even the least admission of absolute truth. For Engels absolute truth is compounded from relative truths. Bogdanov is a relativist; Engels is a dialectician. Here is another, no less important, argument of Engels from the chapter of Anti-Dühring already quoted:
“Truth and error, like all thought-concepts which move in polar opposites, have absolute validity only in an extremely limited field, as we have just seen, and as even Herr Dühring would realise if he had any acquaintance with the first elements of dialectics, which deal precisely with the inadequacy of all polar opposites. As soon as we apply the antithesis between truth and error outside of that narrow field which has been referred to above it becomes relative and therefore unserviceable for exact scientific modes of expression; and if we attempt to apply it as absolutely valid outside that field we really find ourselves altogether beaten: both poles of the antithesis become transformed into their opposites, truth becomes error and error truth” (p. 86). Here follows the example of Boyle’s law (the volume of a gas is inversely proportional to its pressure). The “grain of truth” contained in this law is only absolute truth within certain limits. The law, it appears, is a truth “only approximately.”
Human thought then by its nature is capable of giving, and does give, absolute truth, which is compounded of a sum-total of relative truths. Each step in the development of science adds new grains to the sum of absolute truth, but the limits of the truth of each scientific proposition are relative, now expanding, now shrinking with the growth of knowledge. “Absolute truth,” says J. Dietzgen in his Excursions,— “can be seen, heard, smelt, touched and, of course, also be known, but it is not entirely absorbed (geht nicht auf) into knowledge” (p. 195). “It goes without saying that a picture does not exhaust its object and the artist remains behind his model. . . . How can a picture ‘coincide’ with its model? Approximately it can” (p. 197). “Hence, we can know nature and her parts only relatively; since even a part, though only a relation of nature, possesses nevertheless the nature of the absolute, the nature of nature as a whole (des Naturganzen an sich) which cannot be exhausted by knowledge. . . . How, then, do we know that behind the phenomena of nature, behind the relative truths, there is a universal, unlimited, absolute nature which does not reveal itself to man completely? . . . Whence this knowledge? It is innate; it is given us with consciousness” (p. 198). This last statement is one of the inexactitudes of Dietzgen’s which led Marx, in one of his letters to Kugelmann, to speak of the confusion in Dietzgen’s views. Only by seizing upon such incorrect passages can one speak of a specific philosophy of Dietzgen differing from dialectical materialism. But Dietzgen corrects himself on the same page : “When I say that the consciousness of eternal, absolute truth is innate in us, that it is the one and only a priori knowledge, experience also confirms this innate consciousness” (p. 198).
From all these statements by Engels and Dietzgen it is obvious that for dialectical materialism there is no impassable boundary between relative and absolute truth. Bogdanov entirely failed to grasp this if he could write: “It [the world outlook of the old materialism] sets itself up as the absolute objective knowledge of the essence of things [Bogdanov’s italics] and is incompatible with the historically conditional nature of all ideologies” (Empirio-Monism, Bk. III, p. iv). From the standpoint of modern materialism i.e., Marxism, the limits of approximation of our knowledge to objective, absolute truth are historically conditional, but the existence of such truth is unconditional, and the fact that we are approaching nearer to it is also unconditional. The contours of the picture are historically conditional, but the fact that this picture depicts an objectively existing model is unconditional. When and under what circumstances we reached, in our knowledge of the essential nature of things, the discovery of alizarin in coal tar or the discovery of electrons in the atom is historically conditional; but that every such discovery is an advance of “absolutely objective knowledge” is unconditional. In a word, every ideology is historically conditional, but it is unconditionally true that to every scientific ideology (as distinct, for instance, from religious ideology), there corresponds an objective truth, absolute nature. You will say that this distinction between relative and absolute truth is indefinite. And I shall reply: yes, it is sufficiently “indefinite” to prevent science from becoming a dogma in the bad sense of the term, from becoming something dead, frozen, ossified; but it is at the same time sufficiently “definite” to enable us to dissociate ourselves in the most emphatic and irrevocable manner from fideism and agnosticism, from philosophical idealism and the sophistry of the followers of Hume and Kant. Here is a boundary which you have not noticed, and not having noticed it, you have fallen into the swamp of reactionary philosophy. It is the boundary between dialectical materialism and relativism.
We are relativists, proclaim Mach, Avenarius, Petzoldt. We are relativists, echo Mr. Chernov and certain Russian Machians, would-be Marxists. Yes, Mr. Chernov and Comrades Machians—and therein lies your error. For to make relativism the basis of the theory of knowledge is inevitably to condemn oneself either to absolute scepticism, agnosticism and sophistry, or to subjectivism. Relativism as a basis of the theory of knowledge is not only the recognition of the relativity of our knowledge, but also a denial of any objective measure or model existing independently of humanity to which our relative knowledge approximates. From the standpoint of naked relativism one can justify any sophistry; one may regard it as “conditional” whether Napoleon died on May 5, 1821, or not; one may declare the admission, alongside of scientific ideology (“convenient” in one respect), of religious ideology (very “convenient” in another respect) a mere “convenience” for man or humanity, and so forth.
Dialectics—as Hegel in his time explained—contains the element of relativism, of negation, of scepticism, but is not reducible to relativism. The materialist dialectics of Marx and Engels certainly does contain relativism, but is not reducible to relativism, that is, it recognises the relativity of all our knowledge, not in the sense of denying objective truth, but in the sense that the limits of approximation of our knowledge to this truth are historically conditional.
Bogdanov writes in italics: “Consistent Marxism does not admit such dogmatism and such static concepts” as eternal truths. (Empirio-Monism, Bk. III, p. ix.) This is a muddle. If the world is eternally moving and developing matter (as the Marxists think), reflected by the developing human consciousness, what is there “static” here? The point at issue is not the immutable essence of things, or an immutable consciousness, but the correspondence between the consciousness which reflects nature and the nature which is reflected by consciousness. In connection with this question, and this question alone, the term “dogmatism” has a specific, characteristic philosophical flavour: it is a favourite word used by the idealists and the agnostics against the materialists, as we have already seen in the case of the fairly “old” materialist, Feuerbach. The objections brought against materialism from the standpoint of the celebrated “recent positivism” are just ancient trash.
 See F. Engels, Anti-Dühring , Moscow, 1959, pp. 120-22.
 See F. Engels, Anti-Dühring , Moscow, 1959, p. 127. p. 135
 See the letter of K. Marx to L. Kugelmann of December 5, 1868 (K. Marx, Briefe en Kugelraenn, Inoizdat, 1940).