Source: Georgi Plekhanov, Selected Philosophical Works, Volume 2 (Progress Publishers, Moscow, 1976), pp 379-97. Scanned and prepared for the Marxist Internet Archive by Paul Flewers.
Moscow Editor’s Note: ‘This and the following articles, written by Plekhanov against Conrad Schmidt, present, together with articles against Bernstein, his most brilliant expositions against revisionism of Marxism. Already in February 1898, after Bernstein’s revisionist articles in which he alluded to Conrad Schmidt as an authority in philosophy appeared in the press, Plekhanov decided to come out against Conrad Schmidt. The article was written in French in the autumn of 1898 and published in Neue Zeit, no 5, 29 October 1898. Plekhanov’s article was met with great satisfaction by all revolutionary Marxists. The article was published in Russian in 1906, in the collection of Plekhanov’s works entitled A Critique of Our Critics.’ [The ‘following articles’ are ‘Materialism or Kantianism’ and ‘Materialism Yet Again’ - MIA.]
The reader is aware that Eduard Bernstein is returning to Kant ‘bis zu einem gewissen Grad’, and that this return has, ‘up to a certain point’, been due to the influence of Conrad Schmidt. What are the latter’s philosophical views?
He has set them forth: 1) in an article entitled ‘Ein neues Buch über die materialistische Geschichtsauffassung’ and published in the Berlin Akademiker, 1896 (July and August),  and 2) in an article dealing with a book by Kronenberg, Kant, sein Leben und seine Lehre. The latter article was published in the third supplement to the Berlin newspaper Vorwärts of 17 October 1897.
I propose here to deal with these two articles.
If we are to believe Conrad Schmidt, Marx and Engels declared ‘theoretico-cognitive idealism’ disproved at a time when it still called for refutation. The term theoretico-cognitive idealism should be taken to mean Kant’s idealism; that is self-evident, and Conrad Schmidt has categorically said so. ‘It is not Hegel’s dialectico-evolutionist... metaphysics but Kant’s Critique of Pure Reason that is representative of idealism’, he says.
In fact, Marx and Engels were opponents of the Kantian doctrine, and for the following reason.
In his outstanding work Ludwig Feuerbach, Engels says that Kant’s doctrine of the unknowability of things-in-themselves was rejected already by Hegel, and following the latter though with less profundity, by Feuerbach. He goes on to say:
The most telling refutation of this as of all other philosophical crotchets is practice, namely, experiment and industry. If we are able to prove the correctness of our conception of a natural process by making it ourselves, bringing it into being out of its conditions and making it serve our own purposes into the bargain, then there is an end to the Kantian ungraspable ‘thing-in-itself’. 
Criticising agnosticism in the Introduction to the English translation of his Socialism: Utopian and Scientific, Engels argues in the same way:
Again [he says there], our agnostic admits that all our knowledge is based upon the information imparted to us by our senses. But, he adds, how do we know that our senses give us correct representations of the objects we perceive through them? And he proceeds to inform us that, whenever he speaks of objects or their qualities, he does not in reality mean these objects and qualities, of which he cannot know anything for certain, but merely the impressions which they have produced on his senses. Now, this line of reasoning seems undoubtedly hard to beat by mere argumentation. But before there was argumentation there was action. ‘Im Anfang war die Tat.’ And human action had solved the difficulty long before human ingenuity invented it. The proof of the pudding is in the eating. From the moment we turn to our own use these objects, according to the qualities we perceive in them, we put to an infallible test the correctness or otherwise of our sense-perceptions. If these perceptions have been wrong, then our estimate of the use to which an object can be turned must also be wrong, and our attempt must fail. But if we succeed in accomplishing our aim, if we find that the object does agree with our idea of it, and does answer the purpose we intended it for, then that is positive proof that our perceptions of it and of its qualities, so far, agree with reality outside ourselves. 
Thus, ‘the proof of the pudding is in the eating’. Such is the main argument directed by Engels against Kant’s doctrine, and against agnosticism in general.
In essence, Marx adhered to the same line of argument when, in 1845, he wrote in the second thesis on Feuerbach:
The question whether objective (gegenständliche) truth can be attributed to human thinking is not a question of theory but a practical question. In practice man must prove the truth, that is, the reality and power, the this-sidedness (Diesseitigkeit) of his thinking. 
Herr Conrad Schmidt, however, considers this line of argument most feeble:
It is the same [he writes], as though we said that the fact that we find nexus and conformity with law in external Nature and, thanks to that, we can exert a purposeful influence on Nature - this fact proves with the utmost clarity that our knowledge of Nature is a cognition of what exists in reality; there is absolutely no need for us scientifically to analyse and reject the doubts raised on that score by idealism; we can simply dismiss them as hollow sophistries.
Elsewhere, he expresses himself as follows:
Neither Feuerbach nor Marx and Engels, who experienced his influence, entered into an examination of the fundamental question, and did not take the bull by the horns.
Doctor Conrad Schmidt could say so for the sole reason that he himself has failed to understand wherein lies the fundamental question of Kantian idealism, that is, for the sole reason that he himself has been unable to take the bull by the horns.
I shall try to explain the matter to him in the simplest of terms.
What is a phenomenon? It is a condition of our consciousness evoked by the effect on us of things-in-themselves. That is what Kant says. From this definition it follows that anticipating a given phenomenon means anticipating the effect that a thing-in-itself will have on our consciousness. It may now be asked whether we can anticipate certain phenomena. The answer is: of course, we can. This is guaranteed by our science and our technology. This, however, can only mean that we can anticipate the effect that the things named will have on us. If we can anticipate the effect exerted on us by things-in-themselves, then that means that we are aware (at least ) of some of their properties. So if we are aware of some properties of things-in-themselves, we have no right to call those things unknowable. This ‘sophistry’ of Kant’s falls to the ground, shattered by the logic of his own doctrine. That is what Engels meant by his ‘pudding’.
His proof is as clear and irrefutable as that of a mathematical theorem. Marx and Engels’s theoretical stand is impregnable,  but Doctor Schmidt does not even attempt to gainsay it, confining himself to the remark that to take up such a stand means, not disproving idealism but evading any consideration of the matter. I will leave it to the reader to judge who is ‘evading’ any consideration of the issue: Marx and Engels, or Herr Conrad Schmidt.
I may be asked exactly where Kant said that a phenomenon is a product of the effect on us of things-in-themselves. The answer is provided by the following passage from Prolegomena:
Idealism consists in the affirmation that there exist no other beings but such that think; accordingly the other things we think we perceive would be merely representations in thinking beings, representations that no objects outside of those beings would correspond to. On the contrary, I assert that things are given to us as external objects of our senses; however, we know nothing of what those things can be in themselves; we are aware only of phenomena, that is, the representations that they evoke in us by affecting our senses. Consequently I recognise, in any case, that there exist outside of us bodies, that is, things that are wholly unknown to us by themselves, but which we know from the representations evoked in us by their effect on our senses, and which we denote by the word ‘body’, a word which consequently refers only to the appearance of that object which is unknown to us but yet actually exists. Can this be called idealism? It is its direct opposite. 
There can be no doubt in respect of what Kant has said here; as long as it remains impossible, the objections will also remain irrefutable, which were raised by Marx and Engels to the alleged unknowability of things-in-themselves. To know these things through the medium of the representations they evoke in us means cognising them. The ‘dogmatic’ materialists have never claimed that there exist any other means of cognising things-in-themselves except their effect on our senses. We have shown that sufficiently in our article ‘Bernstein and Materialism’.  It would be useless to repeat the passages quoted in the article, but another two brief statements by two well-known materialists might be cited here. ‘Whatever the effect on us of a given body’, says Holbach, ‘we get to know it only thanks to the changes it brings about in us.’
In La Mettrie’s Abrégé des Systèmes, we come across some interesting remarks to the effect that we can know only some ‘absolutely relative’ properties of ‘external’ things; most of our sensations and representations are so dependent on our organs that they at once change, following changes taking place in the latter.
It should be remembered that ‘to cognise’ has no other meaning in general. To recognise a given thing means recognising its properties. What is meant by a property of a thing? It means the way in which it affects us directly or indirectly. 
To say that things-in-themselves are unknowable to us and that we know only the impressions they produce in us means saying that if we disregard the effect that things-in-themselves have on us, we shall be unable to see how they could affect us. If the eighteenth-century materialists said that we know only the outside, the ‘shell’ of things, they were saying, in essence, exactly what I have expressed in the preceding sentence. But that is an erroneous idea, and the materialists who expressed it were in fact, albeit unwittingly, betraying their own theory of knowledge. Goethe put it far better when he said:
Nichts ist innen, Nichts ist draussen, Denn was innen, das ist aussen! 
This is a truly materialistic view of the subject we are dealing with.
Further: Kant admits that things-in-themselves affect us. Affecting an object means having a certain relationship with that object. Consequently, if we know - at least in part - how things affect us, then we also know - at least in part - the relations existing between us and them. But if we know what those relations are, then we are also aware - this through the agency of our perceptions - of the relations existing between things-in-themselves as such. This, of course, is not ‘immediate’ knowledge, but yet it is knowledge and if we possess it, we have not the least right to assert that the relations existing between things-in-themselves are beyond the reach of our cognition.
Things-in-themselves affect our external senses and evoke certain sensations in us: that is what Kant says. But it means that things cause sensations in us. But the self-same Kant says that the category of causality, like all other categories, cannot be applied to things-in-themselves. In this, he is manifestly contradicting himself.
He contradicts himself just as flatly in the question of time.
Things-in-themselves can affect us evidently only in terms of time, yet Kant considers time merely a subjective form of our contemplation.
Kant’s doctrine also contains other contradictions, which we shall not deal with here. What we have said above is sufficient evidence that this doctrine will remain contradictory as long as we continue to hold, in full accordance with what Kant himself says in his Prolegomena, that things-in-themselves are the cause of our sensations.
Some adherents of Kantianism have noticed this contradiction, and tried to remove it. Thus, for instance, Doctor Lasswitz says the following in his book Die Lehre Kants von der Idealität des Raumes und der Zeit (Berlin, 1883):
It is quite true that neither time nor causality exists for things-in-themselves; this was shown by Kant. But who has affirmed that things-in-themselves are the cause of our sensations? [We have seen that Kant himself asserted this - GP] This erroneous interpretation of Kant’s doctrine is often to be met even with the philosophers. It is constantly being reiterated that things-in-themselves, in affecting our consciousness, cause sensations in us, yet it is clear that a noumenon, as the opposite of what actually exists, simply cannot produce any effect at all. Things-in-themselves can be anything in the world - that is a matter of supreme indifference to our experience. Experience arises through the interaction between reason and sensibility, while a thing-in-itself is always nothing more than a vague reflection, in our understanding, regarding its own limits; that thing exerts just as little influence on the nature of our experience as my reflection in a mirror affects the movements of my body.
To save Kantianism, Herr Lasswitz comes into flagrant contradiction with Kant himself by declaring non-existent and impossible an unambiguous statement from the latter. A strange device! How could Herr Lasswitz have resorted to it?
He could do that only because, while contradicting Kant, he was at the same time able to base himself on the latter.
We have already said that Kant contradicts himself quite frequently. Here, for instance, is what we read in his Critique of Pure Reason:
Understanding accordingly limits... sensibility, without at the same time enlarging its own field. While, moreover, it forbids sensibility to apply its forms and modes to things-in-themselves and restricts it to the sphere of phenomena, it cogitates an object in itself, only, however, as a transcendental object, which is the cause of a phenomenon (consequently not itself a phenomenon), and which cannot be thought either as a quantity or as reality, or as substance (because these notions always require sensuous forms in which to determine an object) - an object, therefore, of which we are quite unable to say whether it can be met with in ourselves or out of us... If we wish to call this object a noumenon, because the representation of it is non-sensuous, we are at liberty to do so. But as we can apply to it none of the conceptions of our understanding, the representation is quite void for us, and is available only for the indication of the limits of our sensuous intuition. 
A transcendental object is the cause of phenomena, yet we cannot apply to it any of our notions of understanding, that is to say, the category of causality is inapplicable to it too. Here we have an obvious contradiction, but we shall not go into that contradiction for the time being. What is unquestionable is that here Kant says something almost completely opposite to what he said in the long excerpt from the Prolegomena quoted above. What does that mean? Is it possible that, in his Prolegomena, Kant holds a different view than in his Critique of Pure Reason?
The answer is both yes and no. The viewpoint of Kant’s Critique of Pure Reason was not always the same. In its first edition, Kant inclined to view the thing-in-itself as an ultimate notion, to which nothing outside of our consciousness corresponds, or - to put it more precisely - Kant was very sceptical of the existence of things outside of our consciousness. His was the point of view of sceptical idealism.
Reproached for this by his opponents, he replied by writing the above-quoted passage in his Prolegomena, and tried to revise the second edition of his Critique in the ‘realistic’ sense. This will be sufficiently borne out by a reference to his Introduction to that edition and to his ‘refutation of idealism’. Nevertheless, this revision was not much of a success; the viewpoint contained in the first edition is discernible in many passages in the second edition, and even the refutation of idealism could be interpreted in a sense that is the opposite of what he said in the Prolegomena. It was due to this circumstance that Doctor Lasswitz could contradict Kant by appealing to Kant himself.
That is indisputable. What is also beyond question is that, despite his numerous contradictions, Kant, following the publication of his Prolegomena, that is, beginning with 1783, rebelled against the idealist interpretation of his doctrine. We shall ask the reader to keep this fact in mind, in view of its great importance.
Let us now see what final results Doctor Lasswitz has arrived at in his exposition of the Kantian philosophy:
All being [he says] is grouped in two kinds of being - the subjective and the objective. The two are to be found in our consciousness, and both possess an equal degree of reality and authenticity. There is no being that exists outside consciousness, but there is a being which is not our I, to wit, the things outside of ourselves. Such things are always arranged in our consciousness in a certain order, and it is exactly that which gives us a consciousness of the I against the world of external objects. 
For the reader to get a better grasp of this viewpoint of Doctor Lasswitz’s, we shall ask him to consider the following lines as well:
Consequently, being, actual and true being, has a spiritual character; there is no other being... Any being - the being of I and not-I - is a definite modification of consciousness; without consciousness there is no being...
The reader, of course, may think that we are still quoting from Lasswitz. He is mistaken. The last two excerpts come from Fichte.  To save Kantianism, that is, to eliminate its internal contradiction, Doctor Lasswitz has been obliged to abandon Kant’s vacillating point of view and go over to the viewpoint of subjective idealism. His neo-Kantianism is merely a more or less conscious neo-Fichteanism.
Consequently, Doctor Lasswitz could not say, together with Doctor Conrad Schmidt, that Kant’s Critique of Pure Reason is representative of idealism. He would have to acknowledge that idealism is best of all represented in Fichte’s Wissenschaftslehre (the theory of science). I am speaking conventionally: he would have to, since I doubt that he would have the courage to do so; as is common knowledge, Kant protested against his doctrine being interpreted in the meaning of the theory of science.  He would have therefore also protested against the above-quoted work by Doctor Lasswitz.
In a letter to Reinhold, Fichte called Kant ‘ein Dreiviertelskopf’ (three-quarters of a mind), saying that the Holy Spirit in Kant was closer to the truth than was Kant’s personality. In their turn, neo-Kantians such as Lasswitz can award Kant the same kind of characteristic, and would be obliged to do so if they were consistent. Whatever they may say, they will never be able to conceal from those with some understanding of the matter that they have abandoned Kant’s doctrine and have leaned towards subjective idealism.
Of course, there also exist neo-Kantians who, like Professor Riehl, do not at all approve of that transition.  The neo-Kantians of the latter ilk are more faithful to their teacher than Doctor Lasswitz is, but then they are more faithful in preserving all their teacher’s inconsistencies.
Incidit in Scyllam qui vult vitare Charybdim!
Which edition of the Critique of Pure Reason should be considered a true expression of idealism? Herr Conrad Schmidt has said not a word to us on this score. He does not even seem to suspect that the viewpoint of the ‘critique’ in the first edition differs from that in the second. Besides, he does not even seem to have an understanding either of the first edition or the second. This will be seen by anyone who will go to the trouble of familiarising himself with the esteemed doctor’s philosophical prose. For instance, he writes the following:
The theory of knowledge on the basis of which Kant exposes the errors of any philosophy that metaphysically strives, with the aid of pure notions, to transcend the confines of experience itself bears the stamp of complete phenomenalism, that is, it regards as a mere phenomenon the world which we see and which serves as the object of our experience.
Kant would have been greatly surprised had he to read these lines written by a man out to defend him against Marx and Engels.
What is experience? That is a question Kant had to answer, as anyone must who would attempt to solve the fundamental problem of philosophy, that of determining the relation of subject to object, of thinking to being. Kant’s theory of knowledge is nothing but an answer to that question. In replying to it, he explained, incidentally, the difference existing, in his opinion, between noumenon and phenomenon, between a thing-in-itself and a phenomenon. One may not be in agreement with Kant - and we are not - but it is quite impossible to consider him a trivial and superficial thinker, as Conrad Schmidt seems to do. Had Kant simply stated that we see phenomena and that our experience pertains to phenomena, that would have meant that his philosophy was built on the absurd petitio principii, on an assumption that the very question awaiting solution has already been solved:
Here the question naturally arises [our doctor continues] whether, in general, we can have immediate knowledge of the external world which we populate, in a way, with the impressions of our senses, and which is made understandable to us with the aid of the category of cause and effect; is not even the most general representation of a corporeal world that is moving in time and space, of a subjective nature?
In Kant’s philosophy, the words ‘external world’ signify all phenomena pertaining to our ‘external experience’, or, as Fichte would have put it, to our nicht-Ich. Even a most superficial acquaintance with this philosophy will suffice to make us understand that our knowledge of this group of phenomena is just as immediate as is our knowledge of the phenomena that pertain to our I. No ‘question’ could have ‘arisen’ along this direction. In just the same way, Kant could not have asked himself whether our representation of the external world was of a subjective nature. It goes without saying that such a representation could not be of any other nature. To question that means having no ‘representation’ of the subject being discussed. But the words ‘external world’ could also refer to things-in-themselves, which are the basis of the world of phenomena. Kant never asked whether any immediate knowledge of these things was possible. For him, immediate knowledge was that which does not depend on the effect of things on us, and he was very well aware of the impossibility of such knowledge. ‘For sensation is possible only within oneself, not without oneself’, he says in the second edition of his Critique of Pure Reason.  But Kant was entitled to ask himself - and did so - whether we can be sure of the existence of things outside of our consciousness. The reader already knows how he answered this question in different periods of his life. Let us now see what Doctor Schmidt has to tell us about that:
Since here, too, it seemed to Kant that there were compelling grounds for doubt, he did not shrink from that final step. To him, space and time, matter and the concepts with the aid of which we decipher the world were something existent only in human representation and thinking; he considered the unknowable, the thing-in-itself, as the primary source whence that sensation flowed. The most underlying foundation of all that exists is something beyond human understanding; everything that takes place is a constant miracle because it stems from what is beyond understanding. The groundlessness [die Bodenlosigkeit] of this thought provided Fichte, Schelling and Hegel with the initial premises for a new kind of metaphysics, which was far more profound and rich in thought, but still more suspended in mid-air and still more lacking in substantial content.
This protracted tirade boils down to Kant having denied the existence of things-in-themselves outside of our consciousness. There is no need for us to expose the ‘groundlessness’ of so categorical an assertion: it contradicts a fact accomplished in time and space.
Doctor Schmidt is firmly convinced that things exist not only in our consciousness. From this angle, he rebukes Kant (the Kant that exists in his ‘consciousness’) quite severely: ‘An intellect that begins to doubt even the objective existence of the material world itself, an existence quite independent of human consciousness, loses firm ground to stand on.’
At this point, we find ourselves constrained to come out in defence of the Sage of Konigsberg. 
We already know that by the time his Prolegomena was published (in 1783), Kant had unreservedly recognised the existence of things-in-themselves, irrespective of our consciousness. This, however, did not and could not prevent him from regarding the material world as one of phenomena. ‘It is only in the empirical mind’, he says, ‘that is, only in connection with experience, that matter is really given to our external senses... as substance in a phenomenon.’ To attribute to such matter, and therefore to the material world created by it, an existence independent of our consciousness would, from Kant’s point of view, mean committing a blunder unforgivable in a thinker.
However that may be, our Doctor refuses to go over to Fichte’s point of view, which is why we invite him to tell us how he solves the contradictions in the Kantian philosophy, those indicated above and obvious even to a certain part of the neo-Kantians. It was these very contradictions that Marx and Engels based themselves on in their criticism of Kant’s philosophy.
Does Doctor Schmidt recognise the existence of these contradictions? What we demand is a forthright answer: yes or no. Conrad Schmidt seems to admit that they do exist, but, instead of taking them into account and trying to resolve them, he prefers to regale us with a piece of ‘writing’ couched in the following terms:
But the bottomless chasm revealed - rightly or wrongly - to... thinking by the Kantian philosophy is only its negative outcome; its genuinely fruitful aspect consists in masterly research into the aggregate operation of our soul-spiritual organisation [seelischgeistigen Organisation], through the agency of which the world of phenomena comes into being... But in this, in the revealing of our representation-faculty, lies the true task pursued by the Critique of Pure Reason, a task that nobody either before or after Kant undertook with such amazing insight. Little as Kant’s analysis can claim to have provided a satisfactory, contradiction-free and final solution of the problem - probably the most difficult of any that scientific research can set itself - it is nevertheless obvious that no attempt to penetrate more deeply into the mysterious depths of the inner world can pass by what has been done by Kant... A return to Kant in no way means, therefore, a reverse movement in the reactionary sense. 
With the aid of ‘writings’ in this vein, one can, of course, evade a consideration of the objections raised to Kant’s philosophy, but such objections cannot possibly be refuted.
In his Critique of Pure Reason, Kant set himself the task of studying our faculty of cognition, not our representation-faculty, as Doctor Schmidt asserts. Why distort what should be set forth with the utmost possible precision? But that is in passing.
Kant takes as his point of departure consciousness as something already prepared; it is not in its becoming that he considers that consciousness. Therein lies the greatest shortcoming in his ‘analysis of consciousness’, and it is surprising that Herr Conrad Schmidt has failed to notice that today when the theory of evolution is triumphant in all branches of science. 
Herr Conrad Schmidt is firmly convinced that the ‘material’ world exists, not only within our consciousness, but also without it. What we would like to hear from him is whether he thinks that this material world, which exists outside of his consciousness, acts on his cognitive faculty. If the reply is no, he will thereby be taking up the stand of subjective idealism, and we shall be unable to understand what it is that convinces him of the existence of a material world independently of his consciousness. If the reply is yes, he will be obliged to recognise, together with Marx and Engels, that Kant’s ‘Unknowable’ is full of contradictions. Logic also imposes obligations, and far more so than noblesse does.
The esteemed Doctor continues:
The materialist who holds on to the objective corporeal world, that is, a world that exists of itself, irrespective of its relations to the human mind, as the basis and source of the life-process is just as little exempt from a study of our spiritual organisation as is the idealist.
The materialist firmly holds the view that the material world has an objective existence. So does Herr Conrad Schmidt. He is convinced that ‘an intellect that begins to doubt even the objective existence of the material world itself, an existence quite independent of human consciousness, loses firm ground to stand on’ (see above). What, then, is the difference between the view of the ‘materialist’, on the one hand, and of Doctor Conrad Schmidt, on the other? I see none.
But the reader will forgive me: there is a difference! The ‘materialist’s’ conclusions are in accord with his premises, while Doctor Conrad Schmidt prefers the ‘pauper’s broth of eclecticism’.  That, as we see, is a big and very serious difference. Who do you give preference to, dear reader: the ‘materialist’, or Doctor Conrad Schmidt? Indeed, de gustibus non est disputandum. 
The ‘materialist’ is not exempt from a study of our spiritual organisation. Of course not! But to study that organisation, the ‘materialist’ addresses himself to experimental psychology, which deals only with phenomena and makes use of methods borrowed from biology. That is the more reliable path.
But that is already not materialism, our learned Doctor exclaims:
Anyone who sees the main distinction of materialism from idealism in a recognition of the law-governed patterns everywhere to be seen in the world of phenomena is obscuring the specific nature of the controversy between materialism and idealism, thereby stripping the concept of materialism of its specific definiteness. Engels himself can serve as a characteristic instance.
But how? What did Engels actually say about the distinction between materialism and idealism?
Herr Conrad Schmidt cites the following passage from the book Ludwig Feuerbach:
The separation from Hegelian philosophy was here [with Marx - GP] also the result of a return to the materialist standpoint. That means it was resolved to comprehend the real world - nature and history - just as it presents itself to everyone who approaches it free from preconceived idealist crotchets. It was decided mercilessly to sacrifice every idealist crotchet which could not be brought into harmony with the facts conceived in their own and not in a fantastic interconnection. And materialism means nothing more than that. 
This passage obviously does not contain a full definition of materialism. But why has Herr Conrad Schmidt cited this passage, and no other? Why has he forgotten the following argument used by Engels?
The question of the position of thinking in relation to being, a question which, by the way, had played a great part also in the scholasticism of the Middle Ages, the question: which is primary, spirit or nature - that question... in relation to the Church was sharpened into this: Did God create the world or has the world been in existence eternally?
The answers which the philosophers gave to this question split them into two great camps. Those who asserted the primacy of spirit to nature... comprised the camp of idealism. The others, who regarded nature as primary, belong to the various schools of materialism. 
According to Engels, materialism is, consequently, a doctrine that regards Nature as something primary in relation to the spirit. Is this definition correct?
Let us recall the French materialists of the eighteenth century. What did the fundamental proposition of their theories consist in?
To ascribe the effects that we witness to Nature, to matter in its different combinations, to the movements inherent in it means giving those effects a general and familiar cause; to wish to mount higher means getting lost in imaginary spaces where we shall never find anything but a multitude of incertitudes and obscurities. Therefore, let us not seek a motive principle outside of a Nature whose essence has always been to exist and move... [says the author of Système de la Nature] What need is there to seek outside of matter a motive force that brings it into play? 
Would you, learned Doctor, like me to provide you with another excerpt? I shall be delighted to do so, and bring another two most convincing passages to your attention:
There can be only natural causes and effects in Nature. All the movements that take place in it follow constant and necessary laws; the natural operations that we are in a position to judge of are sufficient to enable us to uncover those that are concealed from our gaze; we can at least judge of them by analogy; and if we study Nature with attention, the modes of action which it shows teach us not to be disconcerted by those which it refuses to display to us. The causes farthest removed from their effects, indubitably operate through intermediary causes... If, in the chain of such causes, some obstacles appear which hinder our researches, we must endeavour to overcome them; and if we are unable to succeed in that, we shall never be entitled to conclude therefrom that the chain has been broken or that the cause is supernatural. In that case, let us content ourselves with admitting that Nature possesses resources that we do not know, but let us never substitute phantoms, fictions [fabrications as Engels would have said - GP]... for causes that escape us; we would thereby only confirm ourselves in ignorance, halt our researches and persist in stagnating in our errors. 
Let us say that Nature contains everything that we can know... Let us say that Nature does everything and that what she does not do is impossible, that outside of Nature nothing does or can exist... If we cannot discover the primary causes let us content ourselves [mark this, Doctor, mark this!] with the secondary causes and the effects that experience shows us; we must observe the facts available and known to us; they are sufficient to enable us to judge of what we do not know; we must rest content with the faint glimpses of the truth that reaches us through the medium of our external senses [which means, Herr Schmidt, that we must never abandon the platform of experience - GP]. 
The entire Système de la Nature is nothing but a development of this thought, which underlies the entire materialist doctrine of the author, or rather the authors, of this celebrated work.
Our learned Doctor will derive great benefit from listening to what another French materialist had to say:
Man is a creation of Nature; he lives in Nature; he is subordinated to its laws; he cannot cast them off; he cannot even in thought emerge from their confines... To a creature produced by Nature nothing exists beyond the confines of that great whole, of which he forms a part... Those creatures who are said to be above Nature are nothing but chimeras, and we cannot have any idea of them. 
Since man has, to his misfortune, wished to emerge from within the confines of his sphere, he has made an attempt to rise above the visible world [the world of phenomena, Herr Doktor - GP]. He has neglected experience so as to engage in conjectures. 
What do you think of all this, Herr Conrad Schmidt? We find that our old teacher Engels was right. We find that materialism is indeed a doctrine that wishes to explain Nature through its own forces, and which looks upon Nature as something primary in relation to ‘Spirit’. Last, it seems to us that Engels’ definition of materialism can be recognised as the most general and most satisfactory one.
I say: the most general, but I know that there are also exceptions to the general rule. Thus, for instance, the English materialists held that there are creatures that stand above Nature. Suffice it to mention Joseph Priestley, whose doctrine is embellished with a multitude of absolutely non-materialist pendants. But these are all merely pendants, and since the English materialists attach serious significance to such pendants, they have ceased from being materialists. Their materialism, as such, is limited to an examination of the question of the relation of the soul to the body. In this question, however, their views are quite clear and definite.
What I call myself, says the same Priestley, is nothing but organised matter. He goes on to add that he cannot in any way admit the existence of the non-material principle in man: ‘For the same reason that man has been supposed to have a soul, every particular substance to which any powers or properties are ascribed may have a separate soul also.’ 
The book I have quoted from above - Le vrai sens du ‘Système de la Nature’ - is attributed to Helvétius. Has Doctor Schmidt any clear idea of the materialism of this interesting writer, who has been so maligned by the philistines? I shall try to give him at least a slight acquaintance with Helvétius.
While Herr Doktor Schmidt does not doubt the existence of an external world independent of our consciousness, that existence was only probable to Helvétius. The probability (of its existence) is no doubt a very high one and the conclusions stemming from it are equivalent to trustworthiness, yet this is no more than a probability. 
This is so surprising that it could not ever have been expected: Doctor Conrad Schmidt in the role of ‘dogmatist’ in comparison with an eighteenth-century materialist. Speak of ‘progress’ after that!
Perhaps Herr Schmidt will now consent to admit that he - the learned Doctor - has been mistaken, but not Frederick Engels, whom he would correct.
The celebrated English biologist Huxley once said in an article that present-day physiology leads straight to materialism, inasmuch as that name is applicable to a doctrine which asserts that, besides substance which possesses extent, there exists no other thinking substance, and that consciousness, like movement, is a function of matter. Huxley was mistaken only in one thing, namely, in imagining that materialism ever meant something else. All materialists have regarded matter in exactly the same way that, according to Huxley, present-day physiology has taught us to. With their characteristic consistency and fearlessness, the French materialists were able to draw, from that fundamental idea, all the conclusions possible for their time, while the English materialists were afraid to go through to the end. However, all of them shared and defended this underlying foundation of materialist theory.
In conclusion, let us summarise what has been said by us.
1. Herr Doktor Conrad Schmidt has very poorly understood Kant, whom he was out to defend against Marx and Engels.
2. He has also poorly understood Marx and Engels, whom he attempted to criticise on behalf of Kant.
3. He has revealed an absolutely erroneous idea of materialism.
These three grave errors in our learned Doctor are quite sufficient to raise the following question in the reader’s mind: what evil spirit has induced him to engage in argument on things which, of course, could not be ‘unknowable’ to him, but which have evidently remained unknown to him? This is a most interesting question. To answer it, one should recall what Tardes has called the laws of imitation.
The bourgeoisie’s theorists of today firmly adhere to Kant’s philosophy, and condemn materialism without even going to the trouble of getting to know something about it.
Herr Schmidt has followed their example and condemned the materialism of Marx and Engels.
In this, he has forgotten that theorists of the working class are betraying themselves when they set about imitating the theorists of the bourgeoisie.
The bourgeoisie’s aversion from materialism and its predilection for Kant’s philosophy can be very well explained by the present-day state of society. In Kant’s doctrine the bourgeoisie see a powerful ‘spiritual weapon’ in the struggle against the ultimate aspirations of the working class. That is why Kantianism has become the vogue among educated bourgeois.
The lower classes are known to often imitate their superiors, but when do they do so? It is when they have not yet achieved a consciousness of self. Imitation of an upper class by a lower class is a sign that the latter has not yet matured for the struggle for its emancipation; he who wishes to promote that maturity is in duty bound to wage a struggle against that aping as well. The development of consciousness in the oppressed is a tremendous ‘factor of progress’.
We wished to discuss dialectics too with Doctor Schmidt, but lack of space prevents us from doing so. Consequently, that must be put off for some other time, so we shall now say to him: Farewell. Ich salutiere den gelehrten Herrn! 
Notes are by Plekhanov, except those by the Moscow editors of this edition of the work, which are noted ‘Editor’, or the MIA, which are suitably noted.
1. In this article Conrad Schmidt criticises my book Essays on the History of Materialism. I find this criticism very feeble but I do not consider it necessary to reply to it here. What interests me at present is his objections to the materialism of Marx and Engels, and his interpretation of Kant.
2. Karl Marx and Friedrich Engels, Selected Works, Volume 3 (Moscow, 1973), p 347 - Editor.
3. Karl Marx and Friedrich Engels, Selected Works, Volume 3 (Moscow, 1973), p 101 - Editor.
4. Karl Marx and Friedrich Engels, Selected Works, Volume 1 (Moscow, 1973), p 13 - Editor.
5. I do not intend thereby to say that Marx and Engels were the first to advance this proof against Kant. In fact, it can be found already in Jacobi. That, however, is of no significance to me here. I wish merely to show that Marx and Engels criticised Kantianism, and did not ‘evade consideration of it’, as claimed by Doctor Schmidt (who has grasped none of their arguments).
6. Prolegomena (published by JH von Kirchman, Heidelberg, 1882), pp 39-40.
7. See Georgi Plekhanov, Selected Philosophical Works, Volume 2 (Moscow, 1976), pp 325-39. Available at < http://www.marxists.org/archive/plekhanov/1898/07/bernsteinmat.html > - MIA.
8. ‘It is impossible to know more of matter than can be inferred from the phenomena in which it is concerned.’ (Dr Priestley, A Free Discussion on the Doctrine of Materialism (London, 1778), p 20) ‘A definition of any particular thing, substance, or being (call it what you will) cannot be anything more than an enumeration of its known properties... If we take away all the known properties, nothing will be left, of which we can possibly have any idea at all...’ (Ibid, pp 45-46)
9. Nothing is within, nothing is without, for what is within, is without. (Goethes Werke, Volume 2 (Gustave Hempel Edition, Berlin), p 230) - Editor.
10. Kritik der reinen Vernunft (second edition, published by Dr Kehrbach, Reclam), p 258.
11. Die Lehre Kants, p 138.
12. Fichtes Werke, Volume 11, p 32; Volume 3, p 2.
13. In his Erklärung of 7 August 1799.
14. See his Der philosophische Kritizismus, Volume 1 (Leipzig, 1876), pp 423-39, and Volume 2, Part 2 (Leipzig, 1876), pp 128-76.
15. ‘Wanting to avoid Charybdis, he runs into Scylla’ - from Walther von Châtillon’s Alexandreis. That is, trying to avoid one peril, he runs into another - MIA.
16. The Kehrbach edition, p 320.
17. The Sage of Konigsberg, that is, Kant - Editor.
18. Vorwärts!, the above-mentioned article. [That is, in the issue for 17 October 1897 - MIA.]
19. ‘I do not know’, says P Beck, ‘how the theory of evolution is dealt with by those philosophers that adhere to the Kantian theory of knowledge. To Kant, the human soul was a given magnitude always remaining equal to itself. To him, it was a matter of determining its à priori property, deducing all the rest therefrom, but not a matter of showing the origin of that property. But if we proceed from the axiom that Man developed gradually from a bit of protoplasm, then it will be necessary to deduce from the elementary manifestations of the primary cell precisely that which was for Kant the basis of ‘the entire world of phenomena’ (Die Nachahmung und ihre Bedeutung für Psychologie und Völkerkunde (Leipzig, 1904), p 331). The Kantians, however, give no thought to whether their theory is in accord with the doctrine of evolution. It is only of late that some of them, for instance, Windelband, have begun to show some doubt on this score.
20. Karl Marx and Friedrich Engels, Selected Works, Volume 3 (Moscow, 1973), p 335 - Editor.
21. Literally: ‘In matters of taste there is no dispute.’ Usual meaning: ‘There’s no accounting for taste.’ [MIA]
22. Karl Marx and Friedrich Engels, Selected Works, Volume 3 (Moscow, 1973), p 361 - Editor.
23. Karl Marx and Friedrich Engels, Selected Works, Volume 3 (Moscow, 1973), p 346 - Editor.
24. Système de la Nature, Volume 2 (1781 edition), p 146.
25. Système de la Nature, Volume 1 (1781 edition), p 38.
26. Système de la Nature, Volume 2, pp 161-62.
27. Le vrai sens du ‘Système de la Nature’, Chapter 1, and the Introduction to Recueil nécessaire (Leipzig, 1765).
28. Ibid, p 76.
29. A Free Discussion, p 123.
30. Oeuvres complètes d'Helvétius, Volume 1 (Paris, 1828), pp 5-6, note.
31. Citation from Goethe’s Faust, p 397 - Editor. [I bow to the most learned among men! - MIA]