We have seen that the starting point and the fundamental premise of the philosophy of empirio-criticism is subjective idealism. The world is our sensation—this is the fundamental premise, which is obscured but in no wise altered by the word “element” and by the theories of the “independent series,” “co-ordination,” and “introjection.” The absurdity of this philosophy lies in the fact that it leads to solipsism, to the recognition of the existence of the philosophising individual only. But our Russian Machians assure their readers that to “charge” Mach “with idealism and even solipsism” is “extreme subjectivism.” So says Bogdanov in the introduction to the Russian translation of Analysis of Sensations (p. xi), and the whole Machian troop repeat it in a great variety of keys.
Having examined the methods whereby Mach and Avenarius disguise their solipsism, we have now to add only one thing: the “extreme subjectivism” of assertion lies entirely with Bogdanov and Co.; for in philosophical literature writers of the most varied trends have long since disclosed the fundamental sin of Machism beneath all its disguises. We shall confine ourselves to a mere summary of opinions which sufficiently indicate the “subjective” ignorance of our Machians. Let us note in passing that nearly every professional philosopher sympathises with one or another brand of idealism: in their eyes idealism is not a reproach, as it is with us Marxists; but they point out Mach’s actual philosophical trend and oppose one system of idealism by another system, also idealist, but to them more consistent.
O. Ewald, in the book devoted to an analysis of Avenarius’ teachings, writes: “The creator of empirio-criticism commits himself volens nolens to solipsism” (loc. cit., pp. 61-62).
Hans Kleinpeter, a disciple of Mach with whom Mach in his preface to Erkenntnis und Irrtum explicitly declares his solidarity, says: “It is precisely Mach who is an example of the compatibility of epistemological idealism with the demands of natural science [for the eclectic everything is “compatible"!], and of the fact that the latter can very well start from solipsism without stopping there” (Archiv für systematische Philosophie, Bd. VI, 1900, S. 87).
E. Lucka, analysing Mach’s Analysis of Sensations, says “Apart from this . . . misunderstandings (Missverständnis) Mach adopts the ground of pure idealism. . . . It is incomprehensible that Mach denies that he is a Berkeleian” (Kantstudien, Bd. VIII, 1903, S. 416-17).
W. Jerusalem, a most reactionary Kantian with whom Mach in the above-mentioned preface expresses his solidarity ("a closer kinship” of thought than Mach had previously suspected—Vorwort zu “Erkenntnis und Irrtum,” S. x, 1906) says: “Consistent phenomenalism leads to solipsism.” And therefore one must borrow a little from Kant! (See Der kritische Idealismus und die reine Logik [Critical Idealism and Pure Logic], 1905, S. 26.)
R. Hönigswald says: “. . . the immanentists and the empirio-criticists face the alternative of solipsism or metaphysics in the spirit of Fichte, Schelling, or Hegel” (Ueber die Lehre Hume’s von der Realität der Aussendinge [Hume’s Doctrine of the Reality of the External World], 1904, S. 68).
The English physicist Oliver Lodge, in his book denouncing the materialist Haeckel, speaks in passing, as though of something generally known, of “solipsists such as Mach and Karl Pearson” (Sir Oliver Lodge, La vie et la matière [Life and Matter], Paris, 1907, p. 15).
Nature, the organ of the English scientists, through the mouth of the geometrician E. T. Dixon, pronounced a very definite opinion of the Machian Pearson, one worth quoting, not because it is new, but because the Russian Machians have naïvely accepted Mach’s philosophical muddle as the “philosophy of natural science” (A. Bogdanov, introduction to Analysis of Sensations, p. xii, et seq
"The foundation of the whole book,” Dixon wrote, “is the proposition that since we cannot directly apprehend anything but sense-impressions, therefore the things we commonly speak of as objective, or external to ourselves, and their variations, are nothing but groups of sense-impressions and sequences of such groups. But Professor Pearson admits the existence of other consciousness than his own, not only by implication in addressing his book to them, but explicitly in many passages.” Pearson infers the existence of the consciousness of others by analogy, by observing the bodily motions of other people; but since the consciousness of others is real, the existence of people outside myself must be granted! “Of course it would be impossible thus to refute a consistent idealist, who maintained that not only external things but all other consciousness were unreal and existed only in his imagination, but to recognise the reality of other consciousness is to recognise the reality of the means by which we become aware of them, which . . . is the external aspect of men’s bodies.” The way out of the difficulty is to recognise the “hypothesis” that to our sense-impressions there corresponds an objective reality outside of us. This hypothesis satisfactorily explains our sense-impressions. “I cannot seriously doubt that Professor Pearson himself believes in them as much as anyone else. Only, if he were to acknowledge it explicitly, he would have to rewrite almost every page of The Grammar of Science.”
Ridicule—that is the response of the thinking scientists to the idealist philosophy over which Mach waxes so enthusiastic.
And here, finally, is the opinion of a German physicist, L. Boltzmann. The Machians will perhaps say, as Friedrich Adler said, that he is a physicist of the old school. But we are concerned now not with theories of physics but with a fundamental philosophical problem. Writing against people who “have been carried away by the new epistemological dogmas,” Boltzmann says: “Mistrust of conceptions which we can derive only from immediate sense-impressions has led to an extreme which is the direct opposite of former naïve belief. Only sense-impressions are given us, and, therefore, it is said, we have no right to go a step beyond. But to be consistent, one must further ask: are our sense-impressions of yesterday also given? What is immediately given is only the one sense-impression, or only the one thought, namely, the one we are thinking at the present moment. Hence, to be consistent, one would have to deny not only the existence of other people outside one’s self, but also all conceptions we ever had in the past.”
This physicist rightly ridicules the supposedly “new” “phenomenalist” view of Mach and Co. as the old absurdity of philosophical subjective idealism.
No, it is those who “failed to note” that solipsism is Mach’s fundamental error who are stricken with “subjective” blindness.
 Nature, July 21, 1892, p. 269. —Lenin
 Ludwig Boltzmann, Populäre Schriften [Popular Essays), Leipzig, 1905, S. 132. Cf. S. 168, 177, 187, etc. —Lenin
 Archiv für systematische Philosophic (Archives of Systematic Philosophy)—a journal of an idealist tendency published in Berlin from 1895 to 1931, being the second, independent section of the journal Archiv für Philosophie (see Note 83). Its first editor was Paul Natorp. From 1925 the journal was published under the title Archiv für systematische Philosophic und Soziologie (Archives of Systematic Philosophy and Sociology).
 Kantstudien (Kantian Studies)—a German philosophical journal of an idealist tendency, the organ of the neo-Kantians. It was founded by Hans Vaihinger and published, with interruptions, from 1897 to 1944 (Hamburg-Berlin-Cologne). Publication was resumed in 1954. The journal devotes considerable space to comments on Kant’s philosophy. Besides neo-Kantians, its contributors included representatives of other idealist trends.
 Nature—a weekly journal of natural sciences, published in London from 1869.