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By Norman Smith.

Avenarius propounds his philosophy from a standpoint whose originality borders on paradox. While all previous philosophers have regarded experience as awaiting interpretation through metaphysical conceptions, Avenarius holds pure experience to be self-intelligible, and the existing metaphysical theories to be the only facts that call for philosophical explanation. Sometimes he describes his philosophy as the philosophy of pure experience, and sometimes as ‘empiriocriticism’. The former title refers to its content, the latter to its method. He claims that, as regards method, it combines and transcends the philosophies of Hume and Kant. The resulting system is as original in its positive teaching as it is novel in orientation. For though in certain aspects it is closely akin to the metaphysical idealism of Spinoza and Hegel, and recently in this country has been employed as a buttress to the Bradleian philosophy, its most competent critic has described it as the latest, and, in the present state of knowledge, the only tenable form of materialism.[1] A system so strongly affiliated is, even apart from its intrinsic merits, sufficiently remarkable to claim attention. In this article I shall state and criticise the main principles of Avenarius’ philosophy. But in so doing I shall consider them only from the point of view of the problem of knowledge, and as leading up to the statement of his theory of the introjectionist argument. That theory, which has been adopted by several English writers, I reserve for detailed criticism in a second article.[2]

The assumptions which determine Avenarius’ central problem may, if somewhat freely stated, be expressed in the following manner. Nothing exists save experience; and the fundamental characteristic of the content of experience is space. The self apprehends itself as an embodied existence, and so as spatially related to the objects around it. All its perceptions, thoughts and feelings, have reference direct or indirect either to the body or to its environment. Now the spatial world thus experienced varies together with one particular part of itself, namely, with the brain. And this relation is mutual; change in either involves change in both; they stand in functional relation, varying simultaneously with one another. Since nothing exists save as experienced, and since as experienced it involves change in the brain, the relation must be of this nature. On the other hand, however, objects are causally related to the brain, and by their changes produce changes in it. This causal relation as involving sequence and implying independent self-centred existence holds only in the forward order, and therefore excludes the possibility of simultaneous variation. The fundamental problem of metaphysics is to reconcile these two standpoints, the attitude of pure experience with the standpoint adopted in physics and physiology. How can the whole vary simultaneously with a part of itself, and with a part which is causally dependent for its changes upon its relations to the rest of that whole? Avenarius will have nothing to do with the solution offered by subjective idealism—that our experience as purely subjective may vary simultaneously with those brain-states which real external objects have produced. That solution rests on a dualism which Avenarius denounces as ungrounded and absolutely false. Our experienced world is reality, and its functional relation to its own component, the brain, must therefore be reconcilable in some other manner with the equally undoubted causal relations of that brain to the objects external to it.

Avenarius’ detailed analysis of the natural point of view, of the attitude, that is to say, of pure and complete experience, and of its relation to the scientific, I shall now proceed to state. As far as possible I shall avoid the technicalities of Avenarius’ special terminology.

I with all my thoughts and feelings find myself in the midst of a spatial environment.[3] This environment is composed of manifold elements which stand in relations of dependence to one another. Within it I also find my fellow-men. They interfere with the common environment, altering certain parts of it and maintaining others, and of all their actions they through words and gestures reveal the intention and reason. In everything they agree with myself. I accordingly believe that they are beings like myself, and that I am myself a being like them. The spatial world which thus includes both myself and others is for ordinary consciousness a something given, existing, familiar, known, lasting on in thought, constantly rediscovered as fact, and in all its repetitions remaining the same.

This natural consciousness is composed of two elements which from a logical point of view are of very different value, namely, of an experience and of an hypothesis. The experienced—das Vorgefundene—includes, as has just been said, the bodies of my fellow-men. The hypothesis lies in the interpretation which I give to the movements of my fellow-men, in the interpretation that they are expressive, that is, that they are dependent on feeling and will. This hypothetical element can be eliminated. I can, by an effort, think of my fellow-men as being merely automata, extraordinarily complex but without thought and feeling. Our reason for rejecting this attitude is not its unnaturalness or its unfruitfulness. Apart altogether from the difficulties of consistently developing such a view, there is a valid reason for regarding it as false. For, if the elimination of the hypothesis is suggested by its formal logical character as hypothesis (in distinction from experience), its retention is enforced by its actual agreement with experience. In the sole case in which through personal experience I am acquainted in all its relations with the movements of that mechanism which is named ‘man,’ I find it in definite relations to thoughts, feelings, volitions, etc. The denial of the hypothesis therefore involves a theory, equally hypothetical, which in its content is further removed from my own experience than the hypothesis itself. And, since the content of my assumption is the matter of another individual’s experience, though the hypothesis introduces a duality or plurality, it does not cause a dualism in the philosophical sense. Nothing is assumed which is not or cannot be experienced either by myself or by others.

The proof that the natural consciousness involves no dualism demands, however, a fuller analysis of its various elements. The first distinction which Avenarius notes is that between things and thoughts.[4] Here, again, there is duality but no dualism. The portrait of a friend which is before me is comparable with the appearance of my friend which I recall in thought. I can note that the features, etc., are the same or different, and can state the outcome of the comparison as similarity or the reverse. If we interpolate the image between thing and thought we have a series the members of which are comparable with one another. And being, as the natural consciousness admits, thus relatively comparable with one another, there cannot exist that absolute heterogeneity between thoughts and things which some philosophers have asserted. The chief difference between them is, indeed, merely one of time. The sense-experience of, say, a tree, is a first experience; the tree as it reappears in thought or image is a second experience. Were the two absolutely different experiences we could no longer speak of the image as the reappearance of the original experience, and yet at the same time we should have to make it dependent for its occurrence on what, as absolutely different from it, could never account for it.

Avenarius’ next distinction is between what he names the absolute and the relative points of view.[5] Both may be adopted without desertion of pure experience. In the absolute point of view the self is left out of account, the parts of the environment being apprehended in and for themselves. A tree, for instance, is then apprehended as existing in space in definite relations to other things, as changing with the seasons, and as being in all these relations and changes independent of the presence of the self. It may even be known as having been planted before the self was born. The world thus experienced is apprehended as having a past that survives itself in thought and a future that anticipates itself in knowledge, and similarly as having spatial limits that may be transcended in imagination and thought. On the other hand, from the relative point of view the tree is considered not in and for itself, but in itself and for me. It is then perceived that my apprehension of it varies together with it. If its branches are bent or broken my perceptions vary accordingly. Further knowledge, however, reveals that the perception depends not only upon the tree but also upon particular parts of the ‘self,’ namely upon the sense-organs, nerves and brain. Experience reveals these relations of dependence just as it reveals the tree. When the causal series between the tree and the brain-state is not completed, when, for instance, it is interrupted by injury to the nerve-fibres, the self can have no apprehension of the tree. The perception depends, therefore, only mediately on the object, and immediately on changes in the nervous system. And the relative point of view therefore reveals three relations of dependence: (1) between the tree and its perception; (2) between the tree and the nervous system; (3) between the nervous system and the perception. For all three the same formula holds: if the first term be changed the second undergoes corresponding changes. But only in form (2) is the relation causal or physical, and so a special case of the law of the conservation of energy. The two other forms (1 and 3) are logical functional relations.

Much of Avenarius’ best work has consisted in developing a new view of the nature both of mental and of physiological processes, and so in restating the parallelist theory in a thoroughly original manner. He was dissatisfied with the use made by the traditional psychology of the distinction between knowing, feeling and willing, and also with the mental atomism of the associationists. The fundamental characteristic of the mental life is, he holds, that it falls into more or less distinguishable series which in their general features are of a fixed and universal type. Each series originates in a feeling of pain, opposition, or uncertainty. The mind then desires or strives or wills to remove this unpleasant experience; and as a consequence the series of mental experiences sooner or later, through complex mental processes or through simple habitual actions, as the case may be, terminates in the feeling of rest, successful action, and certainty. “We feel lightened and exalted, satisfied and freed.” Such series, which are repeated as often as mental experience occurs, Avenarius has named ‘vital series’.

Avenarius conceives the brain-processes as being of an exactly analogous character.[6] He makes no assumptions as to their special nature; in particular, he rejects as hypothetical, or at least as needless for his purpose, the picture-mechanism of cells and fibres upon which the associationists rely. His only postulates are that the brain, as a living thing, requires both nourishment and exercise, and that in response to the stimuli of a hostile environment it strives to maintain a ‘vital maximum’. Practically, however, he makes the further general assumption that it is capable by internal organisation and outward action of progressively increasing its possible maximum. The ideal maximum would be reached in complete adaptation to an all-comprehensive environment. Physiological processes therefore correspond in type to the mental series. A vital disturbance is either cancelled by other internal changes or removed by a motor response. The stimulus, however, which starts the series need not be, and usually is not, merely injurious. Work is as necessary as nourishment, activity as indispensable as rest. Through response to stimuli the brain organises more and more complex vital series which by enabling it to maintain itself with greater ease in the given environment release energy for more extended activities. In determining, by general dialectical argument, the various types to which such vital series must conform, Avenarius professes to have sketched the programme of future physiological research.

From this point of view Avenarius states the parallelism of psychical and physical in quite a fresh light. He frees the doctrine from dependence upon any particular set of views as to the constitution and working of the nervous system, and yet brings the two series more closely together than had ever been done on any previous theory. Indeed, just on that account he maintains that his view is not properly describable as parallelism. For, while parallelism implies dualism, the relation which he himself traces between the mental and the physiological series is of the same nature as that which exists between the factors in a mathematical function. There is a point for point correspondence which is, he claims, absolutely complete. In this logical functional relation there is no more dualism than exists between the premisses of an argument and the conclusion in which they result.

One very important feature of his position remains for consideration—a feature which is very puzzling to any reader who seeks to approach it from the point of view of the Menschliche Weltbegriff. Petzoldt’s suggestion[7] that Avenarius formulated his theory of vital series through examination of mental experience, and then interpreted the brain-processes in the light of such experience, is undoubtedly correct. None the less Avenarius maintains as the fundamental principle of his Kritik that the only hope of a scientific treatment of mental experience lies in the development of physiology on the lines which he has sketched. Only through a scientific understanding of the brain in its relation to environment can we acquire knowledge of the ultimate nature of experience as a whole. This part of his philosophy appears to have been formed previous to the views developed in the Menschliche Weltbegriff, and to be uncritically based on the scientific teaching prevalent in his day.[8] Being convinced of the closed nature of the physical world, as obedient in all its changes to the principle of the conservation of energy, he asserts as ascertained fact, that consciousness can neither intervene to modify a brain-process nor emerge from it as its effect. In this respect he is a thorough-going parallelist. The body as an automaton conditions the most complex actions in the same complete manner as the merely reflex. All human activity, the highest as well as the lowest, thought as well as bodily action, can on its physiological side be interpreted in the same manner as the reflex functioning of the headless frog.[9] The nature of brain-processes must therefore be determined without any reference to the accompanying mental activities; and as scientific method is limited to the domain marked out by the principle of the conservation of energy, only through this prior determination of the brain-processes can the mental life, which runs a parallel course, be brought within its sphere. The analogies which are established between the cerebral and the mental series co-ordinate them in the closest manner, and in their particular nature are fitted to apply throughout the whole range of mental experience. The brain of an individual is, in Avenarius’ technical phraseology, the ‘empiriokritischer Substitutionswert’ of that individual.[10] Since everything which happens to, or is experienced by, the individual is adequately represented by corresponding processes in the brain, the brain can be substituted functionally for the individual. Exhaustive knowledge of the one yields completed knowledge of both. Stated in terms of Avenarius’ monistic view of experience, this amounts to the assertion that experience in all its concreteness, that is, as mental, varies in exact correspondence with this particular part of itself, and can therefore be explained through it. This is the line of argument developed in the Kritik. In the first volume Avenarius analyses the independent vital series, and in the second volume applies his results in explanation of the conscious life.

To revert, now, to Avenarius’ distinction between the absolute and the relative points of view. His position requires to be carefully interpreted, and would seem to be as follows. All complete experience involves the relative point of view. Though the absolute standpoint states nothing which is not true, and though in experience we apprehend objects as independent of the self, we never experience them save in relation to the self. The absolute standpoint is therefore reached only by abstraction from complete experience. Further, Avenarius refuses to recognise any such thing as the perception of an object. The only reality that can exist is experience, and experience has the two inseparable aspects, inner and outer, psychical and physical, perception and object perceived, thought and object thought about. But to avoid the misleading connotation of these familiar terms, he names the two aspects ‘character’ and ‘content’. To the variable aspect of character belong feeling, perceiving, conjecturing, believing, knowing, etc., the form, whatever it may be, in which we experience anything. As content, on the other hand, he classifies everything which is felt, perceived, conjectured, believed, known, etc. In the relation, character-content, each aspect may vary independently of the other. On the one hand, we may perceive, believe, know, one and the same content; on the other hand, we may take up the same mental attitude to very different things at different periods of our lives. Since experience as character may itself, however, become content of experience, the difference between the two aspects is in the end only relative.

This distinction of subjective and objective aspects must not be confused with the very different distinction between self and not-self.[11] As character or immediacy is a universal aspect of everything experienced, the self and its constituents cannot be experienced more immediately than the not-self. The environment is not given to the self. The ego does not find objects before it.[12] The self as well as the not-self is located in space. They are equally objective, and must be apprehended in exactly the same manner as spatially related within the unity of objective experience. The self differs from other contents in space only through its greater richness and manifoldness, especially as regards the interrelations of its thoughts. Though the self is in the same space with its environment, thoughts which have outlived the environment which they previously constituted form one whole with it, and so stand in highly complex spatial and temporal relations to one another and to the environment which is present here and now. These thoughts, however, as has already been pointed out, have the objectivity that belongs to every content, and are therefore experienced in the same manner as any sensible object in space. Everything in the self, and accordingly the self as a whole, is experienced as having the same kind of existence as its spatial environment. Here again, therefore, as in the distinction between characters and contents, there is duality but no dualism. While the opposition of characters and contents is a distinction between aspects inseparably involved in every single experience, the opposition of self and not-self is a distinction of kindred groups of concrete contents within the field of objective experience. Avenarius’ view of the self is obviously determined by the same naturalistic intention as that of Hume. But while Hume contends that we can know nothing of the ultimate nature of the self, Avenarius seeks to prove that there is nothing in the self which cannot be known by a possible extension of our present experience.

The brain is experienced as independent in the same sense as “material” bodies.[13] Everything, in fact, which is not character is experienced as permanent existence. Avenarius therefore contrasts the dependent characters with the independent vibrations of the nervous system. The characters are dependent not merely in the sense of existing only when and as experienced by the individual, but also as involving the actual existence of the corresponding nervous states in his body at that particular moment. The subject-matter of inquiry remains, however, objective throughout: all we have to do with is, on the one hand, the causal relation of objects to one another and to the nervous system, and on the other the functional relation of states of the nervous system to the complete experience which includes this whole spatial environment with all its causal relations within itself. Throughout we are dealing with reality, and with a reality in which there appears no dualism, and therefore no insoluble problems. The only possible questions are questions which can be solved by a possible extension of experience. Insoluble problems only arise when the true and natural and primitive attitude is departed from, and such departure is in all cases due to that illegitimate process to which Avenarius has given the name, introjection.

But consideration of this falsifying process of introjection I must defer until I have stated more completely Avenarius’ own view of reality. To illustrate the truth of his assertion that there is nothing which need lead to radical alteration of pure experience, and that all questions which are insoluble from its point of view are problems which involve illegitimate assumptions, Avenarius takes the following crucial instance.[14] Two individuals, one of whom is red-blind, apprehend an object as being numerically the same for both, and name it cinnabar. They agree that the number of vibrations which it communicates to the ether is such and such. They also agree that these vibrations are independent of their presence or of their apprehension of the cinnabar. But in regard to the colour they differ: the cinnabar is red to one, black to the other. Now, since these statements as to the colour of the cinnabar contradict one another, both cannot be true, and we seem forced to the conclusion that one or both experiences must be false and therefore merely subjective.

As we have already observed, two points of view are possible without desertion of pure experience. From the absolute point of view, each individual describes reality just as he finds it. But since this, as in the above instance, often leads to contradictory assertions, we are frequently forced to reinterpret it in the fuller light of the relative point of view. We preserve the simpler attitude so long as it works; when it breaks down we correct its conclusions from the more concrete standpoint. Taking into account the relation of the cinnabar to the self we observe that only when the vibrations caused by it affect the nerve-endings, and thereby the brain, do we perceive the coloured cinnabar. Though all observers apprehend the same cinnabar, each apprehends it in relation to a different self, and therefore, it may be, differently. There is, indeed, no fundamental difference between the contradictory perceptions of colour and the varying apprehensions of shape and size at differing distances. In both cases there is difference in the spatial relations and therefore in the causal processes involved. That this difference lies in the one case within the body and in the other case partly outside it is no fundamental difference.

But, it may be urged, this pretended solution is really an admission of the truth of the objection. Throughout the argument spatial arrangement has been assumed to possess a reality that can be accurately defined and which is known as conditioning the apprehension of colour or shape. Since the nature of the vibrations in ether is recognised as constant while the colour is individual, the former alone supplies the means of determining the nature of the cinnabar as it is in itself. In a similar manner our knowledge of the actual size of an object enables us to neutralise differences of subjective appearance.

Now there are here involved two distinct questions. First, the more general problem, which of the many qualities of bodies afford the most economical and effective means of scientifically describing them and of determining their causal relations to one another. Science has answered that question by showing how all qualitative differences are best explained by reference to the spatial and quantitative. And that has been achieved through preservation, with the least possible change, of the absolute standpoint of pure experience. The attitude carries with it no assertion as to the reality or unreality of the secondary qualities. The problem of natural science consists in following out to ideal completion (a completion possible only in thought though always in terms of actual experience) of those quantitative relations which are given us as holding between objects in space.

The second problem, that which alone concerns us in this inquiry, is as to the significance of the relative standpoint which in certain cases requires to be adopted even by the scientist, and which constitutes that modification in the absolute standpoint which I have referred to above as being the least possible. Does the relative standpoint imply that the vibrations which condition colour may be distinguished from colour as reality from appearance, in the same sense in which it may be said that the difference of the white colour of my paper before the perception of a red card from the green colour of the paper after the perception resolves itself into the distinction between a really white and an apparently green object? Such a statement must involve one or other of the three following positions:[15] (1) If the cinnabar communicates a certain rate of vibration to the ether, and the sense-organ stimulated by these vibrations is completely normal, then the cinnabar is red; but if the organ is abnormal it appears different, for instance, to the red-blind black. (2) If the cinnabar communicates a certain rate of vibration to the ether, it depends on the special nature of the sense-organ whether the cinnabar appears red or black. (3) If the cinnabar by means of ether vibrations stimulates our nervous system and thereby causes the sensation of red or black, then these colours, and colours in general, are quite incomparable with their cause, and accordingly are not properties descriptive of the cinnabar as an actually existing thing, but only of its appearance.

No one of these three positions is tenable. As regards the first position, the statement that the cinnabar appears but is not black to the red-blind observer is contrary to fact. The statement can only be made by a normal individual who in setting himself at the point of view of the abnormal observer still retains his own. In describing the abnormal as unreal, he illegitimately assumes that difference of standpoint (and that in this case means for Avenarius different constitution of the nervous system) should involve no difference in the content apprehended; in other words, that the object exists out of relation to the self, and that it has a particular nature and colour in and by itself. The second position involves the same fallacy in an aggravated form. The illegitimate interpretation first made by the normal observer of the object of the abnormal observer is, by a further confusion, extended to the object of his own observation. It therefore misrepresents normal perception as completely as the first position misrepresents the abnormal. The third position, while equally untenable, brings the determining assumptions—and they are of course those involved in the process of introjection—more clearly into view. We may, in the first place, note that even if colour is an effect of which ether-vibrations are the cause, that does not justify us in describing it as appearance. An effect is equally real with its cause. Before colour can be described in that way it must be set in opposition to something actual, and that is only possible through introjection. The objects apprehended must be regarded as merely representations in our heads, as effects produced by the real external objects. These external objects will constitute reality: the representations will be mere appearance. It is then only a question of consistency how far this view is to be carried—whether the ether, the object and the whole spatial environment including the brain itself, are not also merely representations in us, or rather representations in the representation of my head (‘Vorstellungskopf in meiner Kopfvorstellung’).[16]

While still deferring consideration of the process of introjection, the following observations may be made.[17] When it is asserted that an object produces a perception in us, it is assumed that it acts on the sense-organs and brain, and also upon that inner something, soul or consciousness, which introjection adds. What now is meant by ‘acting on’? It covers the conception of physical causation. There is a continuous causal relation between the object and the resulting process in the brain. By acting on the brain it causes that process. This causal relation will not, however, carry us from the brain-state to consciousness. For when followed further it only leads back again through the muscles to the external world. The empirical fact that our apprehension of the object varies together with the brain-state has led to the quite illegitimate assumption, for which there is no evidence, that it likewise is an effect caused by the object. We transform the merely logical functional relation, according to which our world as a whole and in all its parts varies together with changes in this particular part of itself, into a causal relation between our world conceived as an effect and the brain as its external cause. We duplicate the one given reality into an external world and its internal representation.

The most, then, we can ever do is simply to describe what we actually find as constituting reality.[18] From the absolute standpoint we describe the object just as it is presented, and from the relative point of view, while considering it as a term in a relation whose other term is the self, we must also still describe it just as it exists for us. In the latter case, however, the observer no longer asserts without limitation ‘the cinnabar is red’ (or ‘is black,’ as the case may be), but ‘to my eye, or for me, it is red’.[19] By this limiting addition the contradictions involved in the absolute standpoint are removed. So long as the errors of introjection are avoided, this relativism is perfectly unambiguous, and it is also the only possible or consistent attitude. But when misled by a dualistic distinction between the absolute and the relative, between appearance and reality, we ask: What is the object in and for itself?—we raise an unreal, because self-contradictory, problem. And it does not matter whether in answering that question we take up a positive or an agnostic attitude. The two statements—‘The object in and for itself is neither red nor black’; ‘The object in and for itself we do not and cannot know’—are alike untenable.

The sole remaining question, properly stated, is not how the brain, viewed as an external and independent reality, is related to consciousness as something distinct from the brain and dependent upon it, but why our experience as a whole should vary together with one particular part of itself. And, as we have seen, Avenarius seems to hold that that problem is on a level with the question, why the three angles of a triangle should vary together with one another. The laws of logical functional relation between experience and the brain, when discovered, are ultimate facts, beyond which nothing remains to be known. Even the suggestion of the problem implies unconscious reminiscence of dualistic metaphysic. In his Kritik der reinen Erfahrung Avenarius, as I have also already indicated, has formulated the laws which he conceives as holding between the brain and the world which includes it, that is to say, the laws according to which the brain as a reacting agent either neutralises or uses for its self-maintenance the stimuli which are constantly arising from its own internal changes and from the spatial world within which it lies. In accordance with these laws it progressively adapts itself by internal organisation to a more and more comprehensive environment, and so preserves itself through change in relative equilibrium. And as there is a logical functional relation between the states of the brain and our experience as a whole, these laws express the ultimate truth regarding the self in its relation to reality.

I cannot here enter upon Avenarius’ ‘physiology of knowledge’ beyond indicating in the briefest manner how he applies his biological laws in explanation of experience as a whole. I may cite his theory of protective concepts. When the brain is unable to adapt itself to certain stimuli it drains them off through channels (Schutzformen) specially organised for the purpose. In so doing it sacrifices energy, not for the sake of increasing its resources, but merely in order, as far as possible, to preserve itself unchanged in this hostile environment. Similarly, when the mind meets with facts which conflict with its dominant concepts, it invents Beibegriffe, that is to say, modifies its concepts in such a way as to neutralise the conflict in the simplest possible manner and with the least possible change in its accustomed attitude.[20] The concepts, or attitudes of mind, with which the facts of experience conflict are, according to Avenarius, in all cases ultimately due to that process of introjection which has given rise to the animism of primitive man. The spiritualism which results from the animistic conceptions of the soul and of God leads by its own disintegration, as these conceptions are progressively modified to fit the facts of experience, through agnosticism back to naturalism.[21] But further consideration of this view of animism, the understanding of which, and of Avenarius’ view of its relation to introjection, is absolutely essential for a clear conception of his philosophy, I must defer until the next article. Some preliminary criticisms may now, however, be passed upon Avenarius’ general position.

Most readers of Avenarius’ Menschliche Weltbegriff will probably agree that, however convincing as criticism, 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 which is fatal to his own theory. Thereby he surprises the reader into admissions which he could never have elicited by direct argument, and which are indeed inconsistent with the central tenets of his philosophy. The general criticism which I shall seek to justify is, therefore, that Avenarius’ true metaphysical position appears only in the physiology of the Kritik, and that, though his attempt in the Menschliche Weltbegriff to defend that crudely realistic position, and to restate it in a tenable form, has resulted in a most interesting and valuable criticism of subjective idealism, that realistic position itself involves the theory which he rejects. Owing to his refusal to recognise any metaphysical distinction between appearance and reality he cannot escape the position which he so successfully attacks. For, though he asserts character and content to be inseparable, in admitting, as he was bound to do, that content can vary independently of character, he relapses into the dualism which cuts off all possibility of escape from the subjectivist impasse.

At starting Avenarius formulates as self-evident, requiring no detailed analysis, the far-reaching distinction between character and content; and by a quite illegitimate use of it he establishes that view of the self which is all-important for his naturalistic philosophy. By identifying subjectivity with character he is enabled to treat subjectivity as an aspect that colours, quite indifferently, any and every objective content, and therefore as yielding nothing that can constitute the self as a self-centred reacting agent.[22] This same consequence is reinforced by his classification of such different experiences as feeling, desire or volition, and knowledge, under the general heading of character. The whole problem of the nature of characters and of their relation to contents, the problem, that is to say, of the relation of subject and object to one another, is dismissed in the most casual manner in a few short paragraphs. And having thus assumed the right to treat subjectivity as a universal aspect of all possible experience, he has no great difficulty in establishing a purely naturalistic view of the self as merely one group of concrete contents within the field of objective experience. Throughout the Kritik, and indeed in all cases in which he is not directly engaged in defending his monistic view of experience, he practically equates the self with the brain. As the brain is an agent that reacts upon its environment and yet at the same time is an object existing in space, it very conveniently combines his two conflicting views of the self—as subject or character when it is felt as active and as self or content when it is experienced as object. In this way he is enabled in the Kritik to adopt, from a physiological point of view, that subjective and active standpoint which in his Menschliche Weltbegriff he by implication entirely negates.

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; 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, 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, 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 timeworn 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.[23] 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. He entirely fails to solve the central problem which he so suggestively propounds. There are in his system two objective worlds, and therefore two brains; the world (and also, it may be, the brain) apprehended in sense-experience, and the world, including the brain, as scientifically reconstructed in thought. The first as subjective varies not with the brain as a part of itself but with the brain as scientifically conceived.

Spite of all disclaimers,[24] Avenarius’ whole treatment of the relation between consciousness and the brain reveals his secret retention of the extreme parallelist position. In his frequently quoted statement, that the brain is not the seat, organ or supporter, of thought,[25] he rejects the only terms which we possess for defining their connexion. The truth which he seeks to emphasise, namely, that ascription of consciousness to the brain involves confusion of two distinct and contradictory standpoints, is certainly of fundamental importance, but his statement of it is exaggerated, and compares somewhat unfavourably with that which has been given by other writers, as, for instance, by Fechner forty years earlier in his Zend-Avesta.[26] Avenarius’ own term for describing the connexion holding between mind and body, viz., logical functional relation,[27] is only satisfactory if parallelism expresses the ultimate and complete truth; and at the present time there are many signs that even as a provisional working hypothesis it no longer proves adequate to the needs either of physiological or of psychological research. The formula is also open to the serious objection that it exaggerates the kinship of the two parallel series. Avenarius’ contention that the relation holding between them is of the same nature as that between the factors of a mathematical function has no sounder foundation than the quite general analogies derived from his biological interpretation of the vital series. These analogies fail to bridge the gulf which still remains between the purely quantitative attributes of the brain processes and the qualitative characteristics of the mental life.[28] By his own admissions, too, the relation cannot be a ‘logical’ one. For if that were its nature, the relation would hold in both directions, and we would not be limited to ‘deduction’ of the mental from the material, but would likewise be able to reconstruct the brain-processes from our knowledge of mind.

As further evidence that Avenarius’ distinction between his own position and that of parallelism is a distinction without a difference, I may quote the passage in the Bemerkungen,[29] in which he speaks of subjective experience as “Etwas, das Eines mit dem vorgefundenen Bewegten ist, das unauflöslich mit ihm verbunden ist, wie Form und Stoff, und das auch selbst nie ohne Form und nie ohne Inhalt ist und doch immer in anderen Formen und mit anderen Inhalten und zugleich immer in Uebereinstimmung mit dem Gesetz der Erhaltung der Energie”. Though the position expressed in this passage may appear Spinozistic (and Avenarius was of course greatly influenced by Spinoza), it must be borne in mind that his philosophy allows of no metaphysical distinction between appearance and reality, and therefore necessarily remains at the parallelist point of view which Spinoza transcends. In so far as Avenarius’ philosophy deserts the parallelist position it must tend towards materialism. A parallelism of the physical and the psychical, conceived as distinct existences and as standing in functional relation, is the final outcome of his metaphysical speculations. That monistic conception of experience which he unfolds in the Menschliche Weltbegriff, from which he criticises subjective idealism, and upon which he professes to reestablish a scientific realism, he has failed to reconcile with the naturalistic philosophy of his earlier Kritik.

The interest and value of the Menschliche Weltbegriff is, however, by no means lessened when we thus recognise its sturdy idealism as being spoken out of the mouth of its convinced opponent. The bankruptcy of materialism is dramatically represented in its whole-hearted welcome of the old gods disguised under strange names. Idealism has found a prophet in the enemy’s camp. Further confirmation of this interpretation of Avenarius’ philosophy will be gained in the next article from an examination of his theory of the introjectionist argument.

(To be concluded.)


  1. Wundt: “Ueber naiven und kritischen Realismus” in Philosophische Studien, vol. xiii., pp. 334-335, 349 ff.
  2. The following are the titles and dates of Avenarius’ works: Ueber die Phasen des Spinozischen Pantheismus, 1868. Philosophie als Denken der Welt gemäss dem Prinzip des kleinsten Kraftmasses: Prolegomena zu einer Kritik der reinen Erfahrung, 1876. Kritik der reinen Erfahrung, vol. i., 1888; vol. ii., 1890. Der menschliche Weltbegriff, 1891. “Bemerkungen zum Begriff des Gegenstandes der Psychologie” in Vierteljahrsschrift für wissenschaftliche Philosophie, vol. xviii. (1894), vol. xix. (1895). A very useful summary of the Kritik is given by Emil Koch in the Archiv für systematische Philosophie, vol. iv. (1898). Petzoldt has published (1900) the first volume of his Einführung in die Philosophie der reinen Erfahrung. It gives an admirable account of Avenarius’ position as embodied in the Kritik. Its value is, however, seriously impaired by its strange neglect of the Menschliche Weltbegriff. It does not seem to contain a single reference to that work, nor consequently to the more purely metaphysical aspects of Avenarius’ philosophy. Petzoldt’s second volume appeared in 1904, but I have not been able to consult it. An excellent and detailed criticism of Avenarius’ philosophy is given by Wundt in the articles above referred to. Carstanjen has contributed an article on Avenarius to Mind, N.S., vol. vi.
  3. Der Menschliche Weltbegriff, § 6 ff.
  4. Der Menschliche Weltbegriff, § 19; Vierteljahrsschrift, vol. xix., “Bemerkungen,” pp. 2-3, § 121.
  5. Der Menschliche Weltbegriff, § 21.
  6. When the series are physiological he calls them independent vital series, and when mental dependent vital series. His reason for this will appear shortly.
  7. Einführung in die Philosophie der reinen Erfahrung, vol. i., p. 93.
  8. This assertion seems to be justified, though of course Avenarius, like Mach, seeks to vindicate his position by reference to the supreme principle of simplicity or economy (cf. Carstanjen in Mind, N.S., vi., p. 466). As everything within the physical world can, he contends, be explained in accordance with the principle of the conservation of energy, the introduction of spirit or any other ‘metaphysical’ factor is needless and therefore illegitimate. But the belief that the principle is actually sufficient seems to be due to an uncritical extension of results gained in purely physical inquiry to the more complex phenomena of life and consciousness. Cf. Philosophie als Denken der Welt gemäss dem Prinzip des kleinsten Kraftmasses.
  9. Cf. Kritik, vol. ii., p. 486, note 153.
  10. Der Menschliche Weltbegriff, § 158.
  11. Cf. Der Menschliche Weltbegriff, § 138 ff.
  12. Cf. Der Menschliche Weltbegriff, § 143 ff.; Vierteljahrsschrift, vol. xviii., “Bemerkungen,” pp. 145-146, § 22 ff.; pp. 151-152, §§ 40-41; p. 406, § 81.
  13. The brain can itself be brought within the experienced field by opening the skull and making a suitable arrangement of mirrors. Cf. Der Menschliche Weltbegriff, § 129.
  14. Der Menschliche Weltbegriff (Anmerkung 58).
  15. Loc. cit., § vii.
  16. Loc. cit., § viii.
  17. Loc. cit., §§ ix.-xi.
  18. Loc. cit., § xii.
  19. Loc. cit., § xiv.
  20. Avenarius’ test of truth is the immanent idealist criterion, viz., the degree to which a suggested idea harmonises with the rest of our experience. The statics and dynamics in which this criterion results are described with remarkable subtlety in what is one of the most interesting parts of the Kritik (vol. ii., pp. 258-297).
  21. The following concrete instance may be quoted as illustrating Avenarius’ view of the transition from spiritualism to agnosticism: “A single inconceivability—as, for instance, in philosophy the relation of divine omniscience to freedom of the human will, or in daily life an undeserved affliction or an unusually terrible death-agony—is ‘solved’ by reference to the universal ‘incomprehensibility of God’s essence and will’ or to the universal ‘unknowableness’ of his providence . . . the same result is attained by substitution of the ‘insufficiency and incompetence of the human faculty of reason’“ (Kritik, vol. ii., p. 281. Cf. pp. 296-297).
  22. Even desires and feelings are found or given in the same manner as any other experiences. Each has its twofold aspect of character and content. Cf. references given above, in note 2, p. 21.
  23. Der Menschliche Weltbegriff, Anmerkung 58, § xiv.; Vierteljahrsschrift, vol. xix., “Bemerkungen,” note 2 to p. 144. Avenarius’ statement of the same argument in materialistic terms (resulting from his equation of the self with the brain) in the “Bemerkungen” (Vierteljahrsschrift, vol. xix., pp. 136-143, §§ 176-188) is significant of the opposite, and conflicting, trend of his system. Its idealism is in conflict with the underlying materialism.
  24. Cf. Vierteljahrsschrift, vol. xix., “Bemerkungen,” pp. 13-14, §§ 147-148.
  25. “The brain is not the dwelling-place, seat, producer; it is not the instrument or organ, not the supporter or substratum, etc., of thought. Thought is not the inhabitant or commander, not the other half or side, etc., but neither is it a product; it is not even a physiological function, or merely some state of the brain” (Der Menschliche Weltbegriff, § 132). Cf. “Richard Avenarius” by Carstanjen (translated by H. Bosanquet) in Mind, N.S., vol. vi., p. 472; Taylor, Elements of Metaphysics, p. 315.
  26. First edition, vol. i., p. 410 ff.; vol. ii., p. 313 ff. Fechner has given a careful statement of the sense in which such terms as seat, organ, etc., may legitimately be applied to define the relation of consciousness to the brain. Cf. vol. ii., p. 345.
  27. Cf. Vierteljahrsschrift, vol. xix., “Bemerkungen,” pp. 17-18, §§ 153-156.
  28. Cf. Wundt, Philosophische Studien, vol. xiii., p. 356 ff.
  29. Vierteljahrsschrift, vol. xviii., p. 154, § 46. For the sake of accuracy I quote it in the German.