1911 Encyclopædia Britannica/Metaphysics/5 Phenomenal Idealism in Germany

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5.—Phenomenal Idealism in Germany

Phenomenal idealism is the metaphysics which deduces that, as we begin by perceiving nothing but mental phenomena of sense, so all we know at last from these data is also phenomena of sense, actual or possible. So far it is in general agreement not only with Hume, but also with Kant in his first two positions. But it follows Fichte in his revolt against the unknown thing in itself. On the other hand, as the speculative systems of noumenal idealism, starting from Fichte, succeeded one another, like ghosts who “come like shadows, so depart,” without producing conviction, and often in flagrant opposition to the truths of natural science, and when, in consequence, a wave of materialism threatened to submerge mind altogether by reducing it to a function of matter, many philosophers began to despair of the ambitious attempts which had been made to prove that there is a whole world of mind beyond phenomena, as the noumenalists had supposed. Thus they were thrown back on the limits of human knowledge prescribed by Kant, but purged of the unknown thing in itself by Fichte. Phenomenal idealism is the Kantian contention that Nature, as known to science, is phenomena of experience. Unfortunately, the word “phenomenon” is equivocal (see Mind, xiv. 309). Sometimes it is used for any positive fact, as distinguished from its cause. But sometimes also it means what appears, or can appear, to the senses, as distinguished from what does not appear, but can be inferred to exist. Now, Kant and his followers start from this second and narrower meaning, and usually narrow it still more by assuming that what appears to the senses is as mental as the sensation, being undistinguishable from it or from the idea of it, and that an appearance is a mental idea (Vorstellung) of sense; and then they conclude that we can know by inference nothing but such mental appearances, actual and possible, and therefore nothing beyond sensory experience. When, on the other hand, the objects of science are properly described as phenomena, what is meant is not this pittance of sensible appearances, but positive facts of all kinds, whether perceptible or imperceptible, whether capable of being experienced or of being inferred from, but beyond, experience, e.g. the farther side of the moon, which is known to exist only by inference. Hence the doctrine of Kant, that Nature as known to science is phenomena, means one thing in Kantism and another thing in science. In the former it means that Nature is mental phenomena, actual and possible, of sensory experience; in the latter it means that Nature is positive facts, either experienced or inferred. It is most important also to notice that Kantism denies, but science asserts, the logical power of reason to infer actual things beyond experience. But the phenomenal idealists have not, any more than Kant, noticed the ambiguity of the term “phenomenon”; they fancy that, in saying that all we know is phenomena in the Kantian sense of mental appearances, they are describing all the positive facts that science knows; and they follow Kant in supposing that there is no logical inference of actual things beyond experience.

1. The Reaction to Kant.—The reaction to Kant(“Zurück zu Kant!”) was begun by O. Liebmann in Kant und die Epigonen (1865). Immediately afterwards, in 1866, appeared Lange's Geschichte des Materialismus. In 1870 J. B. Meyer published his Kants Psychologie, and in 1871 H. Cohen his more important Kants Theorie der Erfahrung, which led Lange to modify his interpretation of Kant in the second edition of his own book. Lange (q.v.) by his History of Materialism has exercised a profound influence, which is due partly to its apparent success in answering materialism by Kantian arguments, and partly to its ingenious attempt to give to Kantism itself a consistency, which, however, has only succeeded in producing a new Lange. philosophy of Neo-Kantism, differing from Kantism in modifying the a priori and rejecting the thing in itself. Lange to some extent modified the transcendentalism of Kant's theory of the origin of knowledge. A priori forms, according to Kant, are contributions of the mental powers of sense, understanding, and reason; but, according to Lange, they are rooted in “the physico-psychical organization.” This modification was the beginning of a gradual lessening of the antithesis of a priori to a posteriori, until at last the a priori forms of Kant have been transmuted into “auxiliary conceptions,” or “postulates of experience.” But this modification made no difference to the Kantian and Neo-Kantian deduction from the epistemological to the metaphysical. Lange entirely agreed with Kant that a priori forms can have no validity beyond experience when he says: “Kant is at any rate so far justified as the principle of intuition in space and time a priori is in us, and it was a service to all time that he should in this first great example, show that what we possess a priori, just because it arises out of the disposition of our mind, beyond our experience has no longer any claim to validity” (Hist. of Materialism, trans. E. C. Thomas, ii. 203). Hence he deduced that whatever we know from sensations arranged in such a priori forms are objects of our own experience and mental phenomena. Hence also his answer to materialism. Science, says the materialist, proves that all known things are material phenomena. Yes, rejoins Lange, but Kant has proved that material are merely mental phenomena; so that the more the materialist proves his case the more surely he is playing into the hands of the idealist—an answer which would be complete if it did not turn on the equivocation of the word “phenomenon,” which in science means any positive fact, and not a mere appearance, much less a mental appearance, to sense and sensory experience. Having, however, made a deduction, which is at all events consistent, that on Kantian assumptions all we know is mental phenomena, Lange proceeded to reduce the rest of Kantism to consistency. But his ardent love of consistency led him far away from Kant in the end; for he proceeded consistently from the assumption, that whatever we think beyond mental phenomena is ideal, to the logical conclusion that in practical matters our moral responsibility cannot prove the reality of a noumenal freedom, because, as on Kant's assumption we know ourselves from inner sense only as phenomena, we can prove only our phenomenal freedom. Lange thus transmuted inconsistent Kantism into a consistent Neo-Kantism, consisting of these reformed positions: (1) we start with sensations in a priori forms; (2) all things known from these data are mental phenomena of experience; (3) everything beyond is idea, without any corresponding reality being knowable. “The intelligible world,” he concluded, “is a world of poetry.” Our reflection is that there is a great difference between the essence and the consistency of Kant's philosophy. Its essence, as stated by Kant, was to reduce the logical use of reason to mental phenomena of experience in speculation, in order to extend the practical use of reason to the real noumena, or things in themselves, required for morality. Its consistency, as deduced by Lange, was to reduce all use of reason, speculative and practical, to its logical use of proceeding from the assumed mental data of outer and inner sense, arranged a priori, to mental phenomena of experience, beyond which we can conceive ideas but postulate nothing. As H. Vaihinger, himself a profound Kantian of the new school, says: “Critical scepticism is the proper result of the Kantian theory of knowledge.”

There is only one Neo-Kantian way out of this dilemma, but it is to alter the original assumptions of Kant's psychological idealism. This is the alternative of A. Riehl, who in Der philosophische Kriticismus (1876, &c.) proposes the non-Kantian hypothesis that, though things in themselves are unknowable Riehl. through reason alone, they are knowable by empirical intuition, and therefore also by empirical thought starting from intuition. Like all true followers of Kant, Riehl prefers epistemplogy to metaphysics; yet in reality he founds a metaphysics on epistemology, which he calls “critical realism,” so far as it asserts a knowledge of things beyond phenomena, and “critical monism,” so far as it holds that these things are unlike both physical and psychical phenomena, but are nevertheless the common basis of both. He accepts the Kantian positions that unity of consciousness combines sensations by a priori synthesis, and that therefore all that natural science knows about matter moving in space is merely phenomena of outer sense; and he agrees with Kant that from these data we could not infer things in themselves by reason. But his point is that the very sensation of phenomena or appearances implies the things which appear. Sensory knowledge, he says, “is the knowledge of the relations of things through the relations of the sensations of things.” Further, holding that, “like every other perception, the perception of a human body immediately involves the existence of that body,” and, like Fichte, believing in a “common consciousness,” he concludes that the evidence of sense is verified by “common consciousness” of the external world as objective in the Kantian sense of universally valid. He interprets the external world to be the common basis of physical and psychical phenomena. He rightly relies on the numerous passages, neglected by Lange, in which Kant regards things in themselves as neither phenomena nor ideas, but things existing beyond both. But his main reliance is on the passage in the Kritik, where Kant, speaking of the Cartesian difficulty of communication between body and soul, suggests that, however body and soul appear to be different in the phenomena of outer and inner sense, what lies as thing in itself at the basis of the phenomena of both may perhaps be not so heterogeneous (ungleichartig) after all. Riehl elaborates this bare suggestion into the metaphysical theory that the single basis of physical and psychical phenomena is neither bodily nor mental, nor yet space and motion. In order to establish this paradox of “critical monism,” he accepts to a certain extent the psychophysical philosophy of Fechner. He agrees with Fechner that physical process of nerve and psychical process of mind are really the same psychophysical process as appearing on the one hand to an observer and on the other hand to one's own consciousness; and that physical phenomena only produce physical phenomena, so that those materialists and realists are wrong who say that physical stimuli produce sensations. But whereas Fechner and Paulsen hold that all physical processes are universally accompanied by psychical processes which are the real causes of psychical sensations, Riehl rejects this paradox of universal parallelism in order to fall into the equally paradoxical hypothesis that something or other, which is neither physical not psychical, causes both the physical phenomena of matter moving in space and the psychical phenomena of mind to arise in us as its common effects. In supposing a direct perception of such a nondescript thing, he shows to what straits idealists are driven in the endeavour to supplement Kant's limitation of knowledge to phenomena by some sort of knowledge of things.

2. The Reaction to Hume.—When the Neo-Kantians, led by Lange, had modified Kant's hypothesis of a priori forms, and retracted Kant's admission and postulation of things in themselves beyond phenomena and ideas, and that too without proceeding further in the direction of Fichte and the noumenal idealists, there was not enough left of Kant to distinguish him essentially from Hume. For what does it matter to metaphysics whether by association sensations suggest ideas, and so give rise to ideas of substance and causation a posteriori, or synthetic unity of consciousness combines sensations by a priori notions of substance and causation into objects which are merely mental phenomena of experience, when it is at once allowed by the followers of Hume and Kant alike that reason in any logical use has no power of inferring things beyond the experience of the reasoner? In either case, the effective power of inference, which makes us rational beings, is gone. Naturally then the reaction to Kant was followed by a second reaction to Hume, partly under the name of “Positivism,” which has attracted a number of adherents, such as C. Göring (1841-1879), author of an incomplete System der Kritischen Philosophie (1874-1875) and E. Laas (q.v.), and partly under the name of the “physical phenomenology” of E. Mach.

Ernst Mach (q.v.) is a conspicuous instance of a confusion of physics and psychology ending in a scepticism like that of Hume. He tells us how from his youth he pursued physical and psychological studies, how at the age of fifteen he read Kant's Prolegomena, and later rejected the thing in itself, Mach. and came to the conclusion that the world with his ego is one mass of sensations. For a time, under the influence of Fechner's Psychophysics, he thought that Nature has two sides, a physical and a psychological, and added that all atoms have feeling. But in the progress of his physical work, which taught him, as he thought, to distinguish between what we see and what we mentally supply, he soon passed from this noumenalism to a “universal physical phenomenology.” It retains some relics of Fechner's influence; first, the theory of identity, according to which the difference between the physical and psychical is not a dualism, but everything is at once both; and secondly, the substitution of mathematical dependence for physical causality, except that, whereas Fechner only denied causality between physical and psychical, Mach rejects the entire distinction between causality and dependence, on the ground that “the law of causality simply asserts that the phenomena of Nature are dependent on one another.” He comes near to Hume's substitution of succession of phenomena for real causality. He holds, like Hume, that nothing is real except our sensations and complexes of sensory elements; that the ego is not a definite, unalterable, sharply bounded unity, but its continuity alone is important; and that we know no real causes at all, much less real causes of our sensations; or, as he expresses it, bodies do not produce sensations, but complexes of sensations form bodies. If he has any originality, it consists in substituting for the association of ideas the “economy of thinking,” by which he means that all theoretical conceptions of physics, such as atoms, molecules, energy, &c., are mere helps to facilitate our consideration of things. But he limits this power of mind beyond sensations to mere ideas, and like Hume, and also like Lange, holds at last that, though we may form ideas beyond sensations or phenomena, we cannot know things. If we ask how Mach arrived at this scepticism, which is contained in his well-known scientific work Die Mechanik in ihrer Entwickelung (1883; ed. 1908) as well as in his psychological work on the Analysis of Sensations (Beiträge zur Analyse der Empfindungen, 1886), we find two main causes, both psychological and epistemological; namely, his views on sense and on inference. In the first place, he displays in its most naked form the common but unproved idealistic paradox of a sense of sensations, according to which touch apprehends not pressure but a sensation of pressure, sight apprehends not colour but a sensation of colour, and there is no difference between the sensory operation and the sensible object apprehended by any sense, even within the sentient organism. Hence, according to him, sensations are not apprehensions of sensible objects (e.g. pressures felt) from which we infer similar objects beyond sense (e.g. similar pressures of outside things), but are the actual elements out of which everything known is made; as if sensations were like chemical elements. Within the limits of these supposed sensory elements he accords more than many psychologists do to sense; because, following the nativists, Johannes Müller and Hering, he includes sensations of time and space, which, however, are not to be regarded as “pure intuitions” in the style of Kant. But here again he identifies time and space with the sensations of them (Zeitempfindungen and Raumempfindungen). On the assumption, then, that time and space are not objects, but systems, of sensations, he concludes that a body in time and space is “a relatively constant sum of touch-and-light-sensations, joined to the same time-and-space-sensations,” that each man's own body is included in his sensations, and that to explain sensations by motions would only be to explain one set of sensations from another. In short, sensations are elements and bodies complexes of these elements. Secondly, his theory of inference contains the admission that we infer beyond sensations: he remarks that the space of the geometer is beyond space-sensations, and the time of the physicist does not coincide with time-sensations, because it uses measurements such as the rotation of the earth and the vibrations of the pendulum. But by inference beyond sense he does not mean a process of concluding from sensible things to similar things, e.g. from tangible pressures to other similar pressures in the external world. Inference, according to him, is merely mental completion of sensations; and this mental completion has two characteristics: it only forms ideas, and it proceeds by an “economy of thought.” In the course of his learned studies on the history of mechanics he became deeply impressed with Galileo's appeals to simplicity as a test of truth, and converted what is at best only one characteristic of thinking into its essence. According to him, whatever inferences we make, certain or uncertain, are mere economies of thought, adapting ideas to sensations, and filling out the gaps of experience by ideas; whatever we infer, whether bodies, or molecules, or atoms, or space of more than three dimensions, are all without distinction equally provisional conceptions, things of thought; and “bodies or things are compendious mental symbols for groups of sensations symbols which do not exist outside thought.” Moreover, he applies the same scepticism to cause and effect. “In Nature,” says he, “there is no cause and no effect.” He thinks that repetitions of similar conjunctions occur in Nature, the connexion of cause and effect only in abstraction. He refers to Hume as recognizing no causality but only a customary and habitual succession, but adds that Kant rightly recognizes that mere observation cannot teach the necessity of the conjunction. But in reality his theory is neither Hume's theory of association nor Kant's of an a priori notion of understanding under which a given case is subsumed. He thinks that there is a notion of understanding (Verstandesbegriff), under which every new experience is subsumed, but that it has been developed by former experience, instinctively, and by the development of the race, as part of the economy of thinking. “Cause and effect are therefore,” he concludes, “thought-things of economical function (Gedankendinge von ökonomischer Function}.” His philosophy, therefore, is that all known things are sensations and complexes of sensory elements, supplemented by an economy of thinking which cannot carry us beyond ideas to real things, or beyond relations of dependency to real causes.

It is important to understand that Mach had developed this economical view of thought in 1872, more than ten years before the appearance of his work on the history of mechanics as he tells us in the preface, where he adds that at a later date similar views were expressed by Kirchhoff in his Kirchhof. Vorlesungen über mathematische Physik (1874). Kirchhoff asserted that the whole object of mechanics is “to describe the motions occurring in Nature completely in the simplest manner.” This view involves the denial of force as a cause, and the assertion that all we know about force is that the acceleration of one mass depends on that of another, as in mathematics a function depends on a variable; and that even Newton's third law of motion is merely a description of the fact that two material points determine in one another, without reciprocally causing, opposite accelerations. It is evident that Kirchhoff 's descriptive is the same as Mach's economical view. “When I say,” says Mach, “that a body A exerts a force on a body B, I mean that B, on coming into contraposition with A, is immediately affected by a certain acceleration with respect to A.” In a word, Mach and Kirchhoff agree that force is not a cause, convert Newtonian reciprocal action into mere interdependency, and, in old terminology, reduce mechanics from a natural philosophy of causes to a natural history of mere facts. Now, Mach applies these preconceived opinions to “mechanics in its development,” with the result that, though he shows much skill in mathematical mechanics, he misrepresents its development precisely at the critical point of the discovery of Newton's third law of motion.

The true order of discovery, however, was as follows:—

(a) Sir Christopher Wren made many experiments before the Royal Society, which were afterwards repeated in a corrected form by Sir Isaac Newton in the Principia, experimentally proving that bodies of ascertained comparative weights, when suspended and impelled against one another, forced one another back by impressing on one another opposite changes of velocity inversely as their weights and therefore masses; that is, by impressing on one another equal and opposite changes of momentum.

(b) Wallis showed that such bodies reduce one another to a joint mass with a common velocity equal to their joint momentum divided by their joint weights or masses. This result is easily deducible also from Wren's discovery. If m and m' are the masses, u and v' their initial velocities, and V the common velocity, then m(v - V) = m'(V - v'), therefore mv + m'v' = (m + m')V, and hence (mv + m'v')/(m + m') = V.

(c) Wren and Huygens further proved that the law of equal action and reaction, already experimentally established by the former, is deducible from the conservation of the velocity of the common centre of gravity, which is the same as the common velocity of the bodies, that is, deducible from the fact that their common centre of gravity does not change its state of motion or rest by the actions of the bodies between themselves; and they further extended the law to bodies, qua elastic.

(d) Hence, first inductively and then deductively, the third law was originally discovered only as a law of collision or impact between bodies of ascertained weights and therefore masses, impressing on one another equal and opposite changes of momentum, and always reducing one another to a joint mass with a common velocity to begin with, apart from the subsequent effects of elasticity.

(e) Newton in the Principia, repeating and correcting Wren's experiments on collision, and adding further instances from attractive forces of magnetism and gravity, induced the third law of motion as a general law of all forces.

This order of discovery shows that the third law was generalized from the experiments of Wren on bodies of ascertained comparative weights or masses, which are not material points or mass-points. It shows that the bodies impress on one another opposite changes of velocity inversely as their weights or masses; and that in doing so they always begin by reducing one another to a joint mass with a common velocity, whatever they may do afterwards in consequence of their elasticities. The two bodies therefore do not penetrate one another, but begin by acting on one another with a force precisely sufficient, instead of penetrating one another, to cause them to form a joint mass with a common velocity. Bodies then are triply extended substances, each occupying enough space to prevent mutual penetration, and by this force of mutual impenetrability or inter-resistance cause one another to form a joint mass with a common velocity whenever they collide. Withdraw this foundation of bodies as inter-resisting forces causing one another in collision to form a joint mass with a common velocity but without penetration, and the evidence of the third law disappears; for in the case of attractive forces we know nothing of their modus operandi except by the analogy of the collision of inter-resisting bodies, which makes us believe that something similar, we know not what, takes place in gravity, magnetism, electricity, &c. Now, Mach, though he occasionally drops hints that the discovery of the law of collision comes first, yet never explains the process of development from it to the third law of motion. On the contrary, he treats the law of collision with other laws as an application of the third law of motion, because it is now unfortunately so taught in books of mechanics. He has therefore lost sight of the truths that bodies are triply extended, mutually impenetrable substances, and by this force causes which reduce one another to a joint mass with a common velocity on collision, as for instance in the ballistic pendulum; that these forces are the ones we best understand; and that they are reciprocal causes of the common velocity of their joint mass, whatever happens afterwards. In the case of this one force we know far more than the interdependence supposed by Mach and Kirchhoff; we know bodies with impenetrable force causing one another to keep apart. It might have been expected that scepticism on this subject would not have had much effect. But the idealists are only too glad to get any excuse for denying bodily substances and causes; and, while Leibnitz supplied them with the fancied analysis of material into immaterial elements, and Hume with the reduction of bodies to assemblages of sensations, Mach adds the additional argument that bodily forces are not causes at all. In Great Britain Mach's scepticism was welcomed by Karl Pearson to support an idealistic phenomenalism derived from Hume, and by Ward to support a noumenal idealism derived from Lotze. No real advance in metaphysics can take place, and natural science itself is in some danger, until the true history of the evidences of the laws of mechanical force is restored; and then it will soon appear that in the force of collision what we know is not material points determining one another's opposite accelerations, but bodies by force of impenetrable pressure causing one another to keep apart. Mechanics is a natural philosophy of causes.

3. Dualism within Experience.—Besides those philosophies which are reactions to Kant or to Hume, there are a number of other modern systems which start with the common hypothesis that knowledge is experience. The consequence is that whatever is true of experience they transfer to all knowledge. One of the characteristics of actual experience is that its object is, or has been, present to an experiencing subject; and of possible experience that it can be present. As a matter of fact, this characteristic differentiates experience from inference. By inference we know that things, such as the farther side of the moon, which neither are, nor have been, nor can be, present to an experiencing subject on the earth, nevertheless exist. But, on the hypothesis that knowledge contains no inferences beyond experience, it follows that all the objects of knowledge, being objects of experience, are, or have been, or can be, present to an experiencing subject. Hence it is common nowadays to hold that there is indeed a difference between knower and known, ego and non-ego, subject and object, but that they are inseparable; or that all known things are objects and subjects inseparably connected in experience. This view, however, is held in different forms; and two opposite forms have arisen in Germany, “immanent philosophy” and “empirio-criticism,” the former nearer to Kant, the latter to Hume.

Immanent Philosophy is the hypothesis that the world is not transcendent, but immanent in consciousness. Among the upholders of this view are Anton von Leclair, who expresses it in the formula—“Denken eines Seins = gedachtes Sein,” and R. von Schubert-Soldern, who says that Immanent Philosophy. every fragment of the pretended transcendent world belongs to the immanent. But the best known representative of Immanent Philosophy is W. Schuppe, who, in his Erkenntnistheoretische Logik (1878), and in his shorter Grundriss der Erkenntnistheorie und Logik (1894), gives the view a wider scope by the contention that the real world is the common content or object of common consciousness, which, according to him, as according to Fichte, is one and the same in all individual men. Different individual consciousnesses plainly differ in having each its own content, in which Schuppe includes each individual's body as well as the rest of the things which come within the consciousness of each; but they also as plainly agree, e.g. in all admitting one sun. Now, the point of Schuppe is that, so far as they agree, individual consciousnesses are not merely similar, but the same in essence; and this supposed one and the same essence of consciousness in different individuals is what he calls consciousness in general (Bewusstsein überhaupt). While in this identification he follows Fichte, in other respects he is more like Kant. He supposes that the conscious content is partly a posteriori, or consisting of given data of sense, and partly a priori, or consisting of categories of understanding, which, being valid for all objects, are contributed by the common consciousness. He differs, however, from Kant, not only because he will not allow that the given data are received from things in themselves, but also because, like Mach, he agrees with the nativists that the data already contain a spatial determinacy and a temporal determinacy, which he regards as a posteriori elements of the given, not like Kant, as a priori forms of sense. He allows, in fact, no a priori forms except categories of the understanding, and these he reduces, considering that the most important are identity with difference and causality, which in his view are necessary to the judgments that the various data which make up a total impression (Gesammteindruck, Totaleindruck) are each different from the others, together identical with the total impression, and causally connected in relations of necessary sequence and coexistence. At the same time, true to the hypothesis of “immanence,” he rigidly confines these categories to the given data, and altogether avoids the inconsistent tendency of Kant to transfer causality from a necessary relation between phenomena to a necessary relation between phenomena and things in themselves as their causes. Hence he strictly confines true judgment and knowledge to the consciousness of the identity or difference, and the causal relations of the given content of the common consciousness. From this epistemology he derives the metaphysical conclusion that the things we know are indeed independent of my consciousness and of yours, taken individually, or, to use a new phrase, are “trans-subjective”; but, so far from being independent of the common consciousness, one and the same in all of us, they are simply its contents in the inseparable relation of subject and object. To the objection that there are objects, e.g. atoms, which are never given to any consciousness, he returns the familiar Kantian answer that, though unperceived, they are perceptible. The whole known world, then according to him, is the perceived and the perceptible content of common consciousness.

The “empiric-criticism” of R. Avenarius (q.v.) is the hypothesis of the inseparability of subject and object, or, to use his own phraseology, of ego and environment, in purely empirical, or a posteriori form. It is like “immanent philosophy,” in opposing experience to the transcendent; but it Empirio-Criticism. also opposes experience to the transcendental, or a priori. It opposes “pure experience” to “pure reason,” while it agrees with Kant's limitation of knowledge to experience. Avenarius held a view of knowledge very like that of Mach's view of the economy of thinking. In his first philosophical treatise, Philosophie als Denken der Welt gemäss dem Princip des kleinslen Kraftmaasses, Prolegomena zu einer Kritik der reinen Erfahrung (1876), he based his views on the principle of least action, contending that, as in Nature the force which produces a change is the least that can be, so in mind belief tends in the easiest direction. In illustration of this tendency, he pointed out that mind tends to assimilate a new impression to a previous content, and by generalization to bring as many impressions under as few general conceptions as possible, and succeeds so far as it generalizes from pure experience of the given. Nor is there any objection to this economical view of thought, as long as we remember what Avenarius and Mach forget, that the essence of thought is the least action neither more nor less than necessary to the point, which is the reality of things. Afterwards, in his Kritik der reinen Erfahrung (1888-1890), Avenarius aimed at giving a description of pure experience which he identified with the natural view of the world held by all unprejudiced persons. What, then, is this pure experience? “Every human individual,” says he, “originally accepts over against him an environment with manifold parts, other individuals making manifold statements, and what is stated in some way dependent upon the environment.” Statements dependent upon the environment are what he means by pure experience. At first this starting-point looks like dualistic realism, but in reality the author only meant dualism within experience. By the environment he meant not a thing existing in itself, but only a counterpart (Gegenglied) of ourselves as central part (Centralglied). “We cannot,” he adds, “think ourselves as central part away.” He went so far as to assert that, where one assumes that at some time there was no living being in the world, all one means is that there was besides oneself no other central part to whom one's counterparts might also be counterparts. The consequence is that all the world admitted into his philosophy is what he called the “empirio-critical essential co-ordination” (empirio-kritische Prinzipialkoordination), an inseparable correlation of central part and counterpart, of ego and environment. Within this essential co-ordination he distinguished three values: R-values of the environment as stimulus; C-values of the central nervous system; and E-values of human statements—the latter being characterized by that which at the time of its existence for the individual admits of being named, and including what we call sensations, &c., which depend indirectly on the environment and directly on the central nervous system, but are not, as the materialist supposes, in any way reducible to possessions of the brain or any other part of that system. This division of values brings us to the second point in his philosophy, his theory of what he called “vital series,” by which he assayed to explain all life, action and thought. A vital series he supposed to be always a reaction of C against disturbance by R, consisting in first a vital difference, or diminution by R of the maintenance-value of C, and then the recovery by C of its maintenance-value, in accordance with the principle of least action. He further supposed that, while this independent vital series of C is sometimes of this simple kind, at other times it is complicated by the addition of a dependent vital series in E, by which, in his fondness for too general and far-fetched explanations, he endeavoured to explain conscious action and thought. (Thus, if a pain is an E-value directly dependent on a disturbance in C, and a pleasure another E-value directly dependent on a recovery of C, it will follow that a transition from pain to pleasure will be a vital series in E directly dependent on an independent vital series in C, recovering from a vital difference to its maintenance-maximum.) Lastly, supposing that all human processes can in this way be reduced to vital series in an essential co-ordination of oneself and environment, Avenarius held that this empirio-critical supposition, which according to him is also the natural view of pure experiences, contains no opposition of physical and psychical, of an outer physical and an inner psychical world—an opposition which seemed to him to be a division of the inseparable. He considered that the whole hypothesis that an outer physical thing causes a change in one's central nervous system, which again causes another change in one's inner psychical system or soul, is a departure from the natural view of the universe, and is due to what he called “introjection,” or the hypothesis which encloses soul and its faculties in the body, and then, having created a false antithesis between outer and inner, gets into the difficulty of explaining how an outer physical stimulus can impart something into an inner psychical soul. He concluded therefore that, having disposed of this fallacy of introjection, we ought to return to the view of reality as an essential co-ordination of ego and environment, of central part and counterpart, with R-values, C-values and E-values.

It is curious that Avenarius should have brought forward this artificial hypothesis as the natural view of the world, without reflecting that on the one hand the majority of mankind believes that the environment (R) exists, has existed, and will exist, without being a counterpart of any living being as central part (C); and that on the other hand it is so far from being natural to man to believe that sensation and thought (E) are different from, and merely dependent on, his body (C), that throughout the Homeric poems, though soul is required for other purposes, all thinking as well as sensation is regarded as a purely bodily operation. It is indeed difficult to assign any rational place to the empirio-criticism of Avenarius. It is materialistic without being materialism; it is realistic without being realism. Its rejection of the whole relation of physical and psychical makes it almost too indefinite to classify among philosophical systems. But its main point is the essential co-ordination of ego and environment, as central part and counterpart, in experience. It is therefore nearly connected with “immanent philosophy.” Schuppe, indeed, wrote an article in the Vierteljahrsschrift of Avenarius to prove their essential agreement. At the same time Schuppe's hypothesis of one common consciousness uniting the given by a priori categories could hardly be accepted by Avenarius as pufe experience, or as a natural view of the world. His “empirio-criticism” is idealistic dualism within experience in an a posterior form, but with a tendency towards materialism.

4. Voluntaristic Phenomenalism of Wundt.—Wundt's metaphysics will form an appropriate conclusion of this sketch o: German idealism, because his patient industry and eclectic spirit have fitted him to assimilate many of the views of his predecessors. Wundt proves that all idealisms are in a way one. He starts as a phenomenalist from the hypothesis, which Wundt. we have just described, that knowledge is experience containing subject and object in inseparable connexion, and has something in common with the premature attempt of Avenarius to develop the hypothesis of dualism in experience into a scientific philosophy comprehending the universe in the simplest possible manner. Again he agrees with the reaction both to Hume and to Kant in limiting knowledge to mental phenomena, and has affinities with Mach as. well as with Lange. His main sympathies are with the Neo-Kantians, and especially with Lange in modifying the a priori, and in extending the power of reason beyond phenomena to an ideal world; and yet the cry of his phenomenalism is not “back to Kant,” but “beyond Kant.” Though no noumenalist, in many details he is with noumenalists; with Fechner in psychophysics, in psychophysical parallelism, in the independence of the physical and the psychical chains of causality, in reducing ahysical and psychical to a difference of aspects, in substituting impulse for accident in organic evolution, and in wishing to recognize a gradation of individual spiritual beings; with Schopenhauer and Hartmann in voluntarism; and even with Schelling and Hegel in their endeavour, albeit on an artificial method, to bring experience under notions, and to unite subject and object in one concrete reality. He has a special relation to Fichte in developing the Kantian activity of consciousness into will and substituting activity for substantiality as the essence of soul, as well as in breaking down the antithesis between phenomena and things in themselves. At the same time, in spite of his sympathy with the whole development of idealism since Kant, which leads him to reject the thing in itself, to modify a priorism, and to stop at transcendent “ideals,” without postulates of practical reason, he nevertheless has so much sympathy with Kant's Kritik as on its theories of sense and understanding to build up a system of phenomenalism, according to which knowledge begins and ends with ideas, and finally on its theory of pure reason to accord to reason a power of logically forming an “ideal” of God as ground of the moral “ideal” of humanity—though without any power of logically inferring any corresponding reality. He constructs his system on the Kantian order—sense, understanding, reason—and exhibits most clearly the necessary consequence from psychological to metaphysical idealism. His philosophy is the best exposition of the method and argument of modern idealism that we perceive the mental and, therefore, all we know and conceive is the mental.

Wundt founds his whole philosophy on four psychological positions: his phenomenalistic theory of unitary experience, his voluntarism, his actualistic theory of soul, and his psychological theory of parallelism. They are positions also which deeply affect, not only the psychological, but also the metaphysical idealisms of our time, in Germany, and in the whole civilized world.

i. His first position is his phenomenalistic theory of unitary experience. According to him, we begin with an experience of ideas, in which object and idea are originally identical (Vorstellungsobject); we divide this unitary experience into its subjective and objective factors; and especially in natural science we so far abstract the objects as to believe them at last to be independent things; but it is the office of psychology to warn us against this popular dualism, and to teach us that there is only a duality of psychical and physical, which are divisible, not separable, factors of one and the same content of our immediate experience; and experience is our whole knowledge. His metaphysical deduction from this psychological view is that all we know is mental phenomena, “the whole outer world exists for us only in our ideas,” and all that our reason can logically do beyond these phenomena is to frame transcendent “ideals.”

ii. His second position is his voluntarism. He agrees with Schopenhauer that will is the fundamental form of the spiritual. He does not mean that will is the only mental operation; for he recognizes idea derived from sensation, and feeling, as well as will. Moreover, he contends that we can neither have idea without feeling and will, nor will without idea and feeling; that idea alone wants activity, and will alone wants content; that will is ideating and activity (vorstellende Thätigkeit), which always includes motives and ends and consequently ideas. He is therefore a follower of Schopenhauer as corrected by Hartmann. Like these predecessors, and like his younger contemporary Paulsen, in calling will fundamental he includes impulse (Trieb). Accordingly he divides will into two species: on the one hand, simple volition, or impulse, which in his view requires as motive a feeling directed to an end, and therefore an idea, e.g. the impulse of a beast arising from hunger and sight of prey; on the other hand, complex volition issuing in a voluntary act requiring decision (Entscheidung) or conscious adoption of a motive, with or without choice. Like other German voluntarists, he imputes “impulsive will” to the whole organic world. He follows Fechner closely in his answer to Darwin. If he is to be believed, at the bottom of all organic evolution organic impulses becoming habits produce structural changes, which are transmitted by heredity; and as an impulse thus gradually becomes secondarily automatic, the will passes to higher activities, which in their turn become secondarily automatic, and so on. As now he supposes feeling even in “impulsive will” to be directed to an end, he deduces the conclusion that in organic evolution the pursuit of final causes precedes and is the origin of mechanism. But at what a cost! He has endowed all the plants in the world with motives, feelings directed to an end, and ideas, all of which, according to him, are required for impulse! He apparently forgets that mere feelings often produce actions, as when one writhes with pain. But even so, have plants even those lowest impulses from feelings of pain or pleasure? Wundt, however, having gone so far, there stops. It is not necessary for him to follow Schopenhauer, Hartmann and Fechner in endowing the material universe with will or any other mental operation, because his phenomenalism already reduces inorganic nature to mere objects of experiencing subjects. Wundt's voluntarism takes a new departure, in which, however, he was anticipated by the paradox of Descartes: that will is required to give assent to anything perceived (Principia philosophiae, i. 34). Wundt supposes not only that all organisms have outer will, the will to act, but also that all thinking is inner will the will to think. Now there is a will to think, and Aristotle pointed out that thinking is in our power whenever one pleases, whereas sense depends on an external stimulus (De anima, ii. 5). There is also an impulse to think, e.g. from toothache. But it does not follow that thought is will, or even that there is no thinking without either impulse or will proper. The real source of thinking is evidence. Wundt, however, having supposed that all thinking consists of ideas, next supposes that all thinking is willing. What is the source of this paradox? It is a confusion of impulse with will, and activity with both. He supposes that all agency, and therefore the agency of thinking, is will. In detail, to express this supposed inner will of thinking, he borrows from Leibnitz and Kant the term “apperception,” but in a sense of his own. Leibnitz, by way of distinction from unconscious perception, gave the name “apperception” to consciousness. Kant further insisted that this apperception, “I think,” is an act of spontaneity, distinct from sense, necessary to regarding all my ideas as mine, and to combining them in a synthetic unity of apperception; which act Fichte afterwards developed into an active construction of all knowledge, requiring will directed to the end of duty. Wundt, in consequence, thinking with Kant that apperception is a spontaneous activity, and with Fichte that this activity requires will, and indeed that all activity is will, infers that apperception is inner will. Further, on his own account, he identifies apperception with the process of attention, and regards it as an act necessary to the general formation of compound ideas, to all association of ideas, to all imagination and understanding. According to him, then, attention, even involuntary attention, requires inner will; and all the functions imputed by Hume to association, as well as those imputed to understanding by Kant, require apperception, and therefore inner will. At the same time he does not suppose that they all require the same kind of will. In accordance with his previous division of outer will into impulsive and decisive, he divides the inner will of apperception into passive apperception and active apperception. Apperception in general thus becomes activity of inner will, constituting the process of attention, passive in the form of impulsive will required for association, and active in the form of decisive will required for understanding and judgment. Now, beneath these confusing phrases the point to be regarded is that, in Wundt's opinion, though we can receive sensations, we cannot think at all beyond sense, without some will. This exaggeration of the real fact of the will to think ignores throughout the position of little man in the great world and at the mercy of things which drive him perforce to sense and from sense to thought. It is a substitution of will for evidence as ground of assent, and a neglect of our consciousness that we often believe against our will (e.g. that we must die), often without even an impulse to believe, often without taking any interest, or when taking interest in something else of no importance. “The Dean is dead (Pray, what is trumps?).” Yet many psychologists accept the universality of this will to believe, and among them James, who says that “it is far too little recognized how entirely the intellect is built up of practical interests.” We should rather say “far too much.” Wundt, however, goes still farther. According to him, that which acts in all organisms, that which acts in all thinking, that which divides unitary experience into subject and object, the source of self-consciousness, the unity of our mental life, “the most proper being of the individual subject is will.” In short, his whole voluntarism means that, while the inorganic world is mere object, all organization is congealed will, and all thinking is apperceptive will. But it must be remembered that these conclusions are arrived at by confusing action, reaction, life, excitability, impulse, and rational desire, all under the one word “will,” as well as by omitting the involuntary action of intelligence under the pressure of evidence. It may well be that impulsive feeling is the beginning of mind; but then the order of mind is feeling, sense, inference, will, which instead of first is last, and implies the others. To proceed, however, with voluntarism, Wundt, as we have seen, makes personality turn on will. He does not accept the universal voluntarism of Schopenhauer and Hartmann, but believes in individual wills, and a gradation of wills, in the organic world. Similarly, he supposes our personal individual will is a collective will containing simpler will-unities, and he thinks that this conclusion is proved by the continuance of actions in animals after parts of the brain have been removed. In a similar way he supposes our wills are included in the collective will of society. He does not, however, think with Schuppe that there is one common consciousness, but only that there is a collective consciousness and a collective will; not perceiving that then the sun—in his view a mere object in the experience of every member of the collection—would be only a collective sun. Lastly, he believes that reason forms the “ideal” of God as world-will, though without proof of existence. On the whole, his voluntarism, though like that of Schopenhauer and Hartmann, is not the same; not Schopenhauer's, because the ideating will of Wundt's philosophy is not a universal irrational will; and not Hartmann's, because, although ideating will, according to Wundt's phenomenalism, is supposed to extend through the world of organisms, the whole inorganic world remains a mere object of unitary experience.

iii. His third position is his actualistic theory of soul, which he shares with Fichte, Hegel, Fechner and Paulsen. When Fichte had rejected the Kantian soul in itself and developed the Kantian activity of apperception, he considered that soul consists in constructive activity. Fechner added that the soul is the whole unitary spiritual process manifested in the whole unitary bodily process without being a substance. Wundt accepts Fichte's theory of the actuality, and Fechner's synechological view, of the soul. Taking substance entirely in the sense of substrate, he argues that there is no evidence of a substantial substrate beneath mental operations; that there is nothing except unitary experience consisting of ideas, feelings, volitions, and their unity of will; and that soul in short is not substantia, but actus. He does not see that this unity is only apparent, for men think not always, and will not always. Nor does he see that a man is conscious not of idea, feeling, will, experience, but of something conceiving, feeling, willing and experiencing, which he gradually learns to call himself, and that he is never conscious of doing all this “minding” without his body. If, then, these mental operations were merely actuality, they would be actuality of a man's bodily substance. In truth there is no sound answer to Materialism, except that, besides bodily substance, psychical substance is also necessary to explain how man performs mental actualities consciously (see case Physical Realism, ch. v.). Wundt, however, has satisfied himself, like Fechner, that there is no real opposition of body and soul, and concludes, in accordance with his own phenomenalism, that his body is only an object abstracted from his unitary experience, which is all that really is of him.

iv. Hence his fourth point is his psychological theory of parallelism of physical and psychical reduced to identity in unitary experience. Here his philosophy is Fechnerism phenomenalized. He accepts Fechner's extension of Weber's law of the external stimuli of sense, while judiciously remarking that “the physiological interpretation is entirely hypothetical.” He accepts psychophysical parallelism in the sense that every psychical process has a physical accompaniment, every physiological function has a psychical meaning, but neither external stimulus nor physiological stimulus is cause of a psychical process, nor vice versa. Precisely like Fechner, he holds that there is a physical causality and energy and there is a psychical causality and energy, parallels which never meet. He uses this psychical causality to carry out his voluntarism into detail, regarding it as an agency of will directed to ends, causing association and understanding, and further acting on a principle which he calls the heterogony of ends; remarking very truly that each particular will is directed to particular ends, but that beyond these ends effects follow as unexpected consequences, and that this heterogony produces social effects which we call custom. But while thus sharply distinguishing the physical and the psychical in appearance, he follows Fechner in identifying them in reality; except that Fechner's identification is noumenal, Wundt's phenomenal. Wundt does not allow that we know beyond experience any souls of earth, or any other inorganic being. He does not, therefore, allow that there is a universal series of physical and psychical parallels. According to his phenomenalism, the external stimulus and the physiological stimulus are both parallels of the same psychical process; the external body, as well as my body, is merely an object abstracted from an idea of my experience; and what is really known in every case is a unitary experience; divisible, but not separable, into body and soul, physical and psychical factors of one and the same unitary experience. Wundt is confined by his starting-point to his deduction that what we know is mental phenomena, ideas regarded as objects and subjects of experience.

With these four positions in hand, Wundt's philosophy consecutively follows, beginning with his psychology. He begins with psychical elements, sensations and feelings, but he asserts that these always exist in a psychical compound, from which they can be discovered only by analysis and abstraction; and his paradox that a pure sensation is an abstraction is repeated by W. James. Further, Wundt declares that the psychical compound of sensations, with which, according to him, we actually start, is not a complex sensation, but a compound idea; so that I am expected to believe that, when I hear the chord of D, I am not conscious of single sensations of D, F, A, and have only a compound idea of the chord—as if the hearing of music were merely a series of ideas! Wundt, however, has a reason for substituting compound idea for sensation: he accepts Lotze's hypothesis of local signs, and adds a hypothesis of temporal signs. He supposes that we have no sensations of space and time, as the nativists suppose, but that, while local signs give us spatial ideas, feelings of expectation are temporal signs giving us temporal ideas, and that these ideas enter into the psychical compound, which is our actual starting-point. It follows that every psychical compound into which temporal and spatial ideas enter must itself be an idea; and, as time at any rate accompanies all our sensations, it follows that every psychical compound of sensations, containing as it does, always temporal, if not also spatial, ideas, must be a compound idea, and not, as nativists suppose, Schuppe for instance, a compound sensation. The next question is, how compounded? Wundt's answer is that inner impulsive will, in the form of passive apperception, forms compound ideas by association; so that all these operations are necessary to the starting-point. He prefixes to the ordinary associations, which descend from Hume, an association which he calls fusion (Verschmelzung), and supposes that it is a fundamental process of fusing sensations with spatial and temporal ideas into a compound idea. But he also recognizes association by similarity, or assimilation, or “apperception” in Herbart's more confined sense of the word, and association by contiguity, or complication. Recognizing, then, three kinds of association in all, he supposes that they are the first processes, by which inner will, in the form of passive apperception, generates ideas from sense. So far his psychology is a further development of Hume's. But he does not agree with Hume that mind is nothing but sensations, ideas, and associations, but with Kant, that there are higher combinations. According to him, inner decisive will, rising to active apperception, proceeds to what he calls “apperceptive combinations” (Apperceptionverbindungen); first to simple combinations of relating and comparing, and then to complex combinations of synthesis and analysis in imagination and understanding; in consequence of which synthesis issues in an aggregate idea (Gesammtvorstellung), and then at last analysis, by dividing an aggregate idea into subject and predicate, forms a judgment (see further Logic). The main point of this theory is that, if it were true, we should be for ever confined to a jumble of ideas. Wundt, indeed, is aware of the consequences. If judgment is an analysis of an aggregate idea into subject and predicate, it follows, as he says, that “as judgment is an immediate, so is inference a mediate, reference of the members of any aggregate of ideas to one another” (System der Philosophie, 66, first ed.). He cannot allow any inference of things beyond ideas. His psychology poisons his logic.

In his logic, and especially in his epistemology, Wundt appears as a mediator between Hume and Kant, but with more leaning to the latter. While he regards association as lying at the basis of all knowledge, he does not think it sufficient, and objects to Hume that he does not account for necessity, nor for substance and causation as known in the sciences. He accepts on the whole the system of synthetic understanding which Kant superimposed on mere association. Yet he will not proceed to the length of Kant's transcendentalism. Between Hume's a posteriori and Kant's a priori hypothesis he proposes a logical theory of the origin of notions beyond experience. He explains that the arrangement of facts requires “general supplementary notions (Hülfsbegriffe), which are not contained in experience itself, but are gained by a process of logical treatment of this experience.” Of these supplementary notions he holds that the most general is that of causality, coming from the necessity of thought that all our experiences shall be arranged according to ground and consequent. That sense only gives to experience coexistences and sequences of appearances, as Hume said and Kant allowed, is also Wundt's starting-point. How then do we arrive at causality? Not, says Wundt, by association, as Hume said, but by thinking; not, however, by a priori thinking, as Kant said, but by logical thinking, by applying the logical principle of ground and consequent (which Leibnitz had called the principle of sufficient reason) as a causal law to empirical appearances. Now, Wundt is aware that this is not always possible, for he holds that the logical principle of ground belongs generally to the connexion of thoughts, the causal law to the combination of empirical appearances. Nevertheless he believes that, when we can apply measures to the combination of empirical appearances, then we can apply the logical principle as causal law to this combination, and say that one appearance is the cause of another, thus adding a notion of causality not contained in the actual observations, but specializing the general notion of causality. He quotes as an instance that Newton in this way added to the planetary appearances contained in Kepler's laws the gravitation of the planets to the sun, as a notion of causality not contained in the appearances, and thus discovered that gravitation is the cause of the appearances. But Newton had already discovered beforehand in the mechanics of terrestrial bodies that gravitation constantly causes similar facts on the earth, and did not derive that cause from any logical ground beyond experience, any more than he did the third law of motion. Wundt does not realize that, though we can often use a cause or real ground (principium essendi) as a logical ground (principium cognoscendi) for deducing effects, we can do so only when we have previously inferred from experience that that kind of cause does produce that kind of effect (see Logic). Otherwise, logical ground remains logical ground, as in any non-causal syllogism, such as the familiar one from “All men are mortal,” which causes me to know that I shall die, without telling me the cause of death. Wundt, however, having satisfied himself of the power of mere logical thought beyond experience, goes on to further apply his hypothesis, and supposes that, in dealing with the physical world, logical thinking having added to experience the “supplementary notion” of causality as the connexion of appearances which vary together, adds also the “supplementary notion” of substance as substratum of the connected appearances. But, using substance as he does always in the Kantian sense of permanent substratum beneath changi.ig phenomena, and never in the Aristotelian sense of any distinct thing, he proceeds to make distinctions between the applications of causality and of substance. Even in the physical, he confines substance to matter, or what Aristotle would call material causes, thus makes its power to be merely passive, and limits substantial causality to potential energy, while he supposes that actual causality is a relation not of substances but of events. On this false abstraction Sigwart has made an excellent criticism in an appendix at the end of his Logic, where he remarks that we cannot isolate events from the substances of which they are attributes. Motions do not cause motions; one body moving causes another body to move: what we know is causal substances. Secondly, when Wundt comes to the psychical, he naturally infers from his narrow Kantian definition of substance that there is no proof of a substrate over and above all mental operations, and falsely thinks that he has proved that there is no substance mentally operating in the Aristotelian sense. Thirdly, on the grounds that logical thinking adds the notion of substance, as substrate, to experience of the physical, but not of the psychical, and that the most proper being of mind is will, he concludes that wills are not active substances, but substance-generating activities (“nicht thätige Substanzen sondern substanzerzeugende Thätigkeiten,” System, 429).

What kind of metaphysics, then, follows from this compound of psychology and epistemology? As with Kant against Hume, so with Wundt against Mach and Avenarius, the world we know will contain something more than mere complexes of sensations, more than pure experience: with Wundt it will be a world of real causes and some substances, constituted partly by experience and partly by logical thinking, or active inner will. But as with Kant, so with Wundt, this world will be only the richer, not the wider, for these notions of understanding; because they are only contributed to the original experience, and, being mentally contributed, only the more surely confine knowledge to experience of mental phenomena. Hence, according to Wundt, the world we know is still unitary experience, distinguished, not separated, into subject and object, aggregates of ideas analysed by judgment and combined by inference, an object of idea elaborated into causes and substances by logical thinking, at most a world of our ideas composed out of our sensations, and arranged under our categories of our understanding by our inner wills, or a world of our ideating wills; but nothing else. It is Wundt's own statement of his solution of the epistemological problem “that on the one hand the whole outer world exists for us only in our ideas, and that on the other hand a consciousness without objects of idea is an empty abstraction which possesses no actuality” (System, 212-213). There remains his theory of reason. His pupil, Oswald Külpe (1862-       ), who bases his Grundriss der Psychologie on the hypothesis of unitary experience, says in his Einleitung in die Philosophie (1895; 4th ed. 1907) that Wundt in his System derives the right of metaphysics to transcend experience from similar procedure within the limits of the special sciences. This is Wundt's view, but only in the sense that reason passes from ideas to “ideals,” whether in the special sciences or in metaphysics. Reason, as in most modern psychologies and idealisms, is introduced by Wundt, after all sorts of operations, too late; and, when at length introduced, it is described as going beyond ideas and notions to “ideals” (Ideen), as an ideal continuation of series of thoughts beyond given experience—nothing more. Reason, according to Wundt, is like pure reason according to Kant; except that Wundt, receiving Kantism through Neo-Kantism, thinks that reason arrives at “ideals” not a priori, but by the logical process of ground and consequent, and, having abolished the thing in itself, will not follow Kant in his inconsequent passage from pure to practical reason in order to postulate a reality corresponding to “ideals” beyond experience. Wundt, in fact, agrees with Lange: that reason transcends experience of phenomena only to conceive “ideals.” This being so, he finds in mathematics two kinds of transcendence—real, where the transcendent, though not actual in experience, can become partly so, e.g. the divisibility of magnitudes; imaginary, where it cannot, e.g. n-dimensions. He supposes in metaphysics the same transcendence in forming cosmological, psychological, and ontological “ideals.” He supposes real as well as imaginary transcendence in cosmological “ideals”; the former as to the forms of space and time, the latter as to content, e.g. atoms. But he limits psychological and ontological “ideals” entirely to imaginary transcendence. The result is that he confines metaphysical transcendence to “a process into the imaginary” as regards the substantial and causal content of cosmological “ideals,” and altogether as regards psychological and ontological “ideals.” Thus, according to him, in the first place reason forms a cosmological “ideal” of a multitude of simple units related; secondly, it forms a psychological “ideal” of a multitude of wills, or substance-generating activities, which communicate with one another by ideas so that will causes ideas in will, while together they constitute a collective will, and it goes on to form the moral ideal of humanity (das sittliche Menschheitsideal); and, thirdly, it forms an ontological “ideal” of God as ground of this moral “ideal,” and therewith of all being as means to this end, and an “ideal” of God as world-will, of which the world is development, and in which individual wills participate each in its sphere. “Herein,” says Wundt, “consists the imperishable truth of the Kantian proposition that the moral order of the world is the single real proof of the existence of God” (System, 405; cf. 439). “Only,” he adds, “the expression proof is here not admissible. Rational 'ideals' are in general not provable.” As the same limit is applied by him to all transcendent rational “ideals,” and especially to those which refer to the content of the notion of the world, and, like all psychological and ontological “ideals,” belong to the imaginary transcendent, his conclusion is that reason, in transcending experience, logically conceives “ideals,” but never logically infers corresponding realities.

The conclusion that reason in transcending experience can show no more than the necessity of “ideals” is the only conclusion which could follow from Wundt's phenomenalism in psychology, logic, and epistemology. If knowledge is experience of ideas distinguished by inner will of apperception into subject and object in inseparable connexion, if the starting-point is ideas, if judgment is analysis of an aggregate idea, if inference is a mediate reference of the members of an aggregate of ideas to one another, then, as Wundt says, all we can know, and all reason can logically infer from such data, is in our ideas, and consciousness without an object of idea is an abstraction; so that reason, in transcending experience, can show the necessity of ideas and “ideals,” but infer no corresponding reality beyond, whether in nature, or in Man, or in God. Wundt, starting from a psychology of unitary experience, deduces a consistent metaphysics of no inference of things transcending experience throughout—or rather until he came to the very last sentence of his System der Philosophie (1889), where he suddenly passes from a necessity of “ideals” (Ideen), to a necessity of “faith” (Glauben), without “knowledge” (Wissen). He forgets apparently that faith is a belief in things beyond ideas and ideals, which is impossible in his psychology of judgment and logic of inference. The fact is that his System may easily seem to prove more than it does. He describes it as idealism in the form of ideal realism, because it recognizes an ideating will requiring substance as substratum or matter for outer relations of phenomena. But when we look for the evidence of any such will beyond ourselves and our experience, we find Wundt offering nothing but an ontological “ideal” of reason, and a moral “ideal” requiring a religious “ideal,” but without any power of inferring a corresponding reality. The System then ends with the necessity of an “ideal” of God as world-will, but provides no ground for the necessity of any belief whatever in the being of God, or indeed in any being at all beyond our own unitary experience.

Wundt, however, afterwards wrote an Einleitung in die Philosophie (1901; 4th ed., 1906), in which he speaks of realism in the form of ideal realism as the philosophy of the future. It is not to be idealism which resolves everything into spirit, but realism which gives the spiritual and the material each its own place in harmony with scientific consciousness. It is not to be dualistic but monistic realism, because matter is not separate from spirit. It is not to be materialistic but ideal realism, because the physical and the psychical are inseparable parallels inexplicable by one another. It is to be monistic ideal realism, like that of Fichte and Hegel; not, however, like theirs idealistic in method, a Phantastisches Begriffsgebäude, but realistic in method, a Wissenschaftliche Philosophie. It is to be ideal realism, as in the System. It is not to be a species of idealism, as in the System—but of realism. How are we to understand this change of front? We can only explain it by supposing that Wundt wishes to believe that, beyond the “ideal,” there really is proof of a transcendent, ideating, substance-generating will of God; and that he is approaching the noumenal voluntarism of his younger contemporary Paulsen. But to make such a conversion from phenomenalism plausible, it is necessary to be silent about his whole psychology, logic, and epistemology, and the consequent limitation of knowledge to experience, and of reason to ideas and “ideals,” without any power of inferring corresponding things.

What a pity it is that Wundt had committed himself by his psychology to phenomenalism, to unitary experience, and to the limitation of judgment and reason to ideas and ideals! For his phenomenalism prevents him from consistently saying the truth inferred by reason—that there is a world beyond experience, a world of Nature, and a will of God, real as well as ideal. To understand Wundt is to discover what a mess modern psychology has made to metaphysics. To understand phenomenal idealism in Germany is to discover what a narrow world is to be known from the transcendental idealism of Kant shorn of Kant's inconsistencies. To understand noumenal idealism in Germany and the rise of metaphysical idealism in modern times is to discover that psychological is the origin of all metaphysical idealism. If we perceive only what is mental, all that we know is only mental. But who has proved that psychological starting-point? Who has proved that, when I scent an odour in my nostrils, I apprehend not odour but a sensation of odour; and so for the other senses? Sensation, as Aristotle said, is not of itself: it is the apprehension of a sensible object in the organism. I perceive pressure, heat, colour, sound, flavour, odour, in my five senses. Having felt reciprocal pressures in touch, I infer similar pressures between myself and the external world.