Avenarius’ doctrine of the principal co-ordination is expounded in The Human Concept of the World and in the Notes. The second was written later, and in it Avenarius emphasises that he is expounding, it is true in a somewhat altered form, something that is not different from the Critique of Pure Experience and The Human Concept of the World, but exactly the same (Notes, 1894, S. 137 in the journal quoted above). The essence of this doctrine is the thesis of “the indissoluble (unauflösliche) co-ordination [i.e., the correlative connection] of the self and the environment” (p. 146). “Expressed philosophically,” Avenarius says here, one can say the “self and not-self.” We “always find together” (immer ein Zusammen-vorgefundenes) the one and the other, the self and the environment. “No full description of what we find (des Vorgefundenem) can contain an ‘environment’ without some self (ohne ein Ich) whose environment it is, even though it be only the self that is describing what is found (das Vorgefundene)” (p. 146). The self is called the central term of the co-ordination, the environment the counter-term (Gegenglied). (Cf. Der menschliche Weltbegriff, 2. Auflage, 1905, S. 83-84, § 148 ff.)
Avenarius claims that by this doctrine he recognises the full value of what is known as naïve realism, that is, the ordinary, non-philosophical, naïve view which is entertained by all people who do not trouble themselves as to whether they themselves exist and whether the environment, the external world, exists. Expressing his solidarity with Avenarius, Mach also tries to represent himself as a defender of “naïve realism” (Analysis of Sensations, p. 39). The Russian Machians, without exception, believed Mach’s and Avenarius’ claim that this was indeed a defence of “naïve realism": the self is acknowledged, the environment is acknowledged—what more do you want?
In order to decide who actually possesses the greatest degree of naïveté, let us proceed from a somewhat remote starting point. Here is a popular dialogue between a certain philosopher and his reader:
"Reader : The existence of a system of things [according to ordinary philosophy] is required and from them only is consciousness to be derived.
"Author : Now you are speaking in the spirit of a professional philosopher . . . and not according to human common sense and actual consciousness. . . .
"Tell me, and reflect well before you answer: Does a thing appear in you and become present in you and for you otherwise than simultaneously with and through your consciousness of the thing? . . .
"Reader : Upon sufficient reflection, I must grant you this.
"Author : Now you are speaking from yourself, from your heart. Take care, therefore, not to jump out of yourself and to apprehend anything otherwise than you are able to apprehend it, as consciousness and [the italics are the philosopher’s] the thing, the thing and consciousness; or, more precisely, neither the one nor the other, but that which only subsequently becomes resolved into the two, that which is the absolute subjective-objective and objective-subjective.”
Here you have the whole essence of the empirio-critical principal co-ordination, the latest defence of “naïve realism” by the latest positivism! The idea of “indissoluble” co-ordination is here stated very clearly and as though it were a genuine defence of the point of view of the common man, undistorted by the subtleties of “the professional philosophers.” But, as a matter of fact, this dialogue is taken from the work of a classical representative of subjective idealism, Johann Gottlieb Fichte, published in 1801.
There is nothing but a paraphrase of subjective idealism in the teachings of Mach and Avenarius we are examining. The claim that they have risen above materialism and idealism, that they have eliminated the opposition between the point of view that proceeds from the thing to consciousness and the contrary point of view—is but the empty claim of a renovated Fichteanism. Fichte too imagined that he had “indissolubly” connected the “self” and the “environment,” the consciousness and the thing; that he had “solved” the problem by the assertion that a man cannot jump out of himself. In other words, the Berkeleian argument is repeated: I perceive only my sensations, I have no right to assume “objects in themselves” outside of my sensation. The different methods of expression used by Berkeley in 1710, by Fichte in 1801, and by Avenarius in 1891-94 do not in the least change the essence of the matter, viz., the fundamental philosophical line of subjective idealism. The world is my sensation; the non-self is “postulated” (is created, produced) by the self ; the thing is indissolubly connected with the consciousness; the indissoluble co-ordination of the self and the environment is the empirio-critical principal co-ordination;—this is all one and the same proposition, the same old trash with a slightly refurbished, or repainted, signboard.
The reference to “naïve realism,” supposedly defended by this philosophy, is sophistry of the cheapest kind. The “naïve realism” of any healthy person who has not been an inmate of a lunatic asylum or a pupil of the idealist philosophers consists in the view that things, the environment, the world, exist independently of our sensation, of our consciousness, of our self and of man in general. The same experience (not in the Machian sense, but in the human sense of the term) that has produced in us the firm conviction that independently of us there exist other people, and not mere complexes of my sensations of high, short, yellow, hard, etc.—this same experience produces in us the conviction that things, the world, the environment exist independently of us. Our sensation, our consciousness is only an image of the external world, and it is obvious that an image cannot exist without the thing imaged, and that the latter exists independently of that which images it. Materialism deliberately makes the “naïve” belief of mankind the foundation of its theory of knowledge.
Is not the foregoing evaluation of the “principal co-ordination” a product of the materialist prejudice against Machism? Not at all. Specialists in philosophy who cannot be accused of partiality towards materialism, who even detest it and who accept one or other of the idealist systems, agree that the principal co-ordination of Avenarius and Co. is subjective idealism. Wundt, for instance, whose interesting opinion was not understood by Mr. Yushkevich, explicitly states that Avenarius’ theory, according to which a full description of the given or the found is impossible without some self, an observer or describer, is “a false confusion of the content of real experience with reflections about it.” Natural science, says Wundt, completely abstracts from every observer. “Such abstraction is possible only because the attribution (Hinzudenken) of an experiencing individual to every content of experience, which the empirio-critical philosophy, in agreement with the immanentist philosophy, assumes, is in general an empirically unfounded assumption arising from a false confusion of the content of real experience with reflections about it” (loc. cit., p. 382). For the immanentists (Schuppe, Rehmke, Leclair, Schubert-Soldern), who themselves voice—as we shall see later—their hearty sympathy with Avenarius, proceed from this very idea of the “indissoluble” connection between subject and object. And W. Wundt, before analysing Avenarius, demonstrated in detail that the immanentist philosophy is only a “modification” of Berkeleianism that however much the immanentists may deny their kinship with Berkeley we should not allow verbal differences to conceal from us the “deeper content of these philosophical doctrines,” viz., Berkeleianism or Fichteanism.
The English writer Norman Smith, analysing Avenarius’ Philosophy of Pure Experience, puts this criticism in an even more straightforward and emphatic form:
"Most readers of Avenarius’ The Human Concept of the World will probably agree that, however convincing as criticism [of idealism], it is tantalisingly illusive in its positive teaching. So long as we seek to interpret his theory of experience in the form in which it is avowedly presented, namely, as genuinely realistic, it eludes all clear comprehension: its whole meaning seems to be exhausted in negation of the subjectivism which it overthrows. It is only when we translate Avenarius’ technical terms into more familiar language that we discover where the real source of the mystification lies. Avenarius has diverted attention from the defects of his position by directing his main attack against the very weakness [i.e., of the idealist position] which is fatal to his own theory.” “Throughout the whole discussion the vagueness of the term experience stands him in good stead. Sometimes it means experiencing and at other times the experienced, the latter meaning being emphasised when the nature of the self is in question. These two meanings of the term experience practically coincide with his important distinction between the absolute and the relative standpoints [I have examined above what significance this distinction has for Avenarius]; and these two points of view are not in his philosophy really reconciled. For when he allows as legitimate the demand that experience be ideally completed in thought [the full description of the environment is ideally completed by thinking of an observing self], he makes an admission which he cannot successfully combine with his assertion that nothing exists save in relation to the self. The ideal completion of given reality which results from the analysis of material bodies into elements which no human senses can apprehend [here are meant the material elements discovered by natural science, the atoms, electrons, etc., and not the fictitious elements invented by Mach and Avenarius], or from following the earth back to a time when no human being existed upon it, is, strictly, not a completion of experience but only of what is experienced. It completes only one of the two aspects which Avenarius has asserted to be inseparable. It leads us not only to what has not been experienced but to what can never by any possibility be experienced by beings like ourselves. But here again the ambiguities of the term experience come to Avenarius’ rescue. He argues that thought is as genuine a form of experience as sense-perception, and so in the end falls back on the time-worn argument of subjective idealism, that thought and reality are inseparable, because reality can only be conceived in thought, and thought involves the presence of the thinker. Not, therefore, any original and profound re-establishment of realism, but only the restatement in its crudest form of the familiar position of subjective idealism is the final outcome of Avenarius’ positive speculations” (p. 29).
The mystification wrought by Avenarius, who completely duplicates Fichte’s error, is here excellently exposed. The much-vaunted elimination of the antithesis between materialism (Norman Smith should not have used the term realism) and idealism by means of the term “experience” instantly proves to be a myth as soon as we proceed to definite and concrete problems. Such, for instance, is the problem of the existence of the earth prior to man, prior to any sentient being. We shall presently speak of this point in detail. Here we will note that not only Norman Smith, an opponent of his theory, but also W. Schuppe, the immanentist, who warmly greeted the appearance of The Human Concept of the World as a confirmation of naïve realism unmasks Avenarius and his fictitious “realism.” The fact of the matter is that Schuppe fully agrees with such “realism,” i.e., the mystification of materialism dished out by Avenarius. Such “realism,” he wrote to Avenarius, I, the immanentist philosopher, who have been slandered as a subjective idealist, have always claimed with as much right as yourself, hochverehrter Herr Kollege. "My conception of thought . . . excellently harmonises (verträgt sich vortrefflich) with your ‘Theory of pure experience’” (p. 384). “The connection and inseparability of the two terms of the co-ordination” are in fact provided only by the self (das Ich, the abstract, Fichtean self-consciousness, thought divorced from the brain). “That which you desired to eliminate you have tacitly assumed"—so Schuppe wrote to Avenarius (p. 388). And it is difficult to say who more rudely unmasks Avenarius the mystifier—Smith by his straightforward and clear refutation, or Schuppe by his enthusiastic opinion of Avenarius’ crowning work. The kiss of Wilhelm Schuppe in philosophy is no better than the kiss of Peter Struve or Menshikov in politics.
O. Ewald, who praises Mach for not succumbing to materialism, speaks of the principal co-ordination in a similar manner: “If one declares the correlation of central term and counter-term to be an epistemological necessity which cannot be avoided, then, even though the word ‘empirio-criticism’ be inscribed on the signboard in shrieking letters, one is adopting a standpoint that differs in no way from absolute idealism. [The term is incorrect; he should have said subjective idealism, for Hegel’s absolute idealism is reconcilable with the existence of the earth, nature, and the physical universe without man, since nature is regarded as the “otherness” of the absolute idea.] On the other hand, if we do not hold fast to this co-ordination and grant the counter-terms their independence, then the way is at once opened for every metaphysical possibility, especially in the direction of transcendental realism” (op. cit., pp. 56-57).
By metaphysics and transcendental realism, Herr Friedländer, who is disguised under the pseudonym Ewald, means materialism. Himself professing one of the varieties of idealism, he fully agrees with the Machians and the Kantians that materialism is metaphysics—"from beginning to end the wildest metaphysics” (p. 134). On the question of the “transcendence” and the metaphysical character of materialism he is in agreement with Bazarov and all our Machians, and of this we shall have occasion to say more later. Here again it is important to note how in fact the shallow and pedantic claim to have transcended idealism and materialism vanishes, and how the question arises inexorably and irreconcilably. “To grant the counter-terms their independence” means (if one translates the pretentious language of the affected Avenarius into common parlance) to regard nature and the external world as independent of human consciousness and sensation. And that is materialism. To build a theory of knowledge on the hypothesis of the indissoluble connection between the object and human sensation ("complexes of sensations” as identical with bodies; “world-elements” that are identical both psychically and physically; Avenarius’ co-ordination, and so forth) is to land inevitably into idealism. Such is the simple and unavoidable truth that with a little attention may be easily detected beneath the piles of affected quasi-erudite terminology of Avenarius, Schuppe, Ewald and the others, which deliberately obscures matters and frightens the general public away from philosophy.
The “reconciliation” of Avenarius’ theory with “naïve realism” in the end aroused misgivings even among his own disciples. For instance, R. Willy says that the common assertion that Avenarius came to adopt “naïve realism” should be taken cum grano salis.— “As a dogma, naïve realism would be nothing but the belief in things-in-themselves existing outside man (ausserpersönliche) in their perceptible form." In other words, the only theory of knowledge that is really created by an actual and not fictitious agreement with “naïve realism” is, according to Willy, materialism! And Willy, of course, rejects materialism. But he is compelled to admit that Avenarius in The Human Concept of the World restores the unity of “experience,” the unity of the “self” and the environment “by means of a series of complicated and extremely artificial subsidiary and intermediary conceptions” (p. 171). The Human Concept of the World, being a reaction against the original idealism of Avenarius, “entirely bears the character of a reconciliation (eines Ausgleiches) between the naïve realism of common sense and the epistemological idealism of school philosophy. But that such a reconciliation could restore the unity and integrity of experience [Willy calls it Grunderfahrung, that is, basic experience—another new world!], I would not assert” (p. 170).
A valuable admission! Avenarius’ “experience” failed to reconcile idealism and materialism. Willy, it seems, repudiates the school philosophy of experience in order to replace it by a philosophy of “basic” experience, which is confusion thrice confounded....
 Johann Gottlieb Fichte, Sonnenklarer Bericht an das grössere Publikum über das eigentliche Wesen der neuesten Philosophie. Ein Versuch, die Leser zum Verstehen zu zwingen [A Clear Account to the Broad Public of the True Nature of Recent Philosophy. An Attempt to Get the Reader to Understand], Berlin, 1801, S. 178-80. —Lenin
 Loc. cit., § C: “The Immanentist Philosophy and Berkeleian Idealism,” pp. 373 and 375; cf. pp. 386 and 407. “The Unavoidability of Solipsism from This Standpoint,” p. 381. —Lenin
 Norman Smith, “Avenarius’ Philosophy of Pure Experience,” Mind, Vol. XV, 1906, pp. 27-28. —Lenin
 See W. Schuppe’s open letter to R. Avenarius in Vierteljahrsschrift für wissenschaftliche Philosophie, Bd. XVII, 1893, S. 364-88. —Lenin
 R. Willy, Gegen die Schulweisheit, S. 170. —Lenin
 Mind—a magazine of an idealist tendency, devoted to questions of philosophy and sociology. It was published from 1876 in London, and is now issued in Edinburgh; the first editor was Professor Croom Robertson.
 Struve, P. B—a former “legal Marxist”, one of the founders of the Cadet Party (see Note 67), a monarchist and counter-revolutionary.
Menshikov M. 0.—a contributor to the reactionary newspaper Novoye Vremya. Lenin called him “a true watchdog of the tsarist Black Hundreds”.