Until the year 1890, when James's Principles were published, the psychology of Hume reigned absolutely in philosophy.^[A] All empiricists accepted it enthusiastically, as the sum of philosophic wisdom; all apriorists submitted to it, even in supplementing and modifying it by 'transcendental' and metaphysical additions; in either case it remained uncontested as psychology, and, by propounding an utterly erroneous analysis of the mind and its experience, entangled philosophy in inextricable difficulties.

Hume had, as philosophers commonly do, set out from the practically sufficient analysis of experience which all find ready-made in language. He accepted, therefore, from common sense the belief that physical reality is composed of a multitude of separate existences that act on one another, and tried to conceive mental life strictly on the same analogy. His theory of experience, therefore, closely parallels the atomistic theory of matter. Just as the physicist explains bodies as collections of discrete particles, so Hume reduced all the contents of the mind to a number of elementary sensations. Whether the mind was reflecting on its own internal ideas, or whether it was undergoing impressions which it supposed to come from an external source, all that was really happening was a succession of detached sensations. It seemed to Hume indisputable that every distinct perception (or 'impression') was a distinct existence, and that all 'ideas' were equally distinct, though fainter, copies of impressions. Beyond impressions and ideas it was unnecessary to look. Thus to look at a chessboard was to have a number of sensations of black and white arranged in a certain order, to listen to a piece of music was to experience a succession of loud and soft auditory sensations, to handle a stone was to receive a group of sensations of touch. To suppose that anything beyond these sensory units was ever really experienced was futile fiction. Experience was a mosaic, of which the stones were the detached sensations, and their washed-out copies, the ideas.

If this analysis of the mind were correct—and its correctness was not disputed for more than a hundred years, for were not the sensations admitted to be the ultimate analysis of all that was perceived?—the common-sense belief that knowledge revealed a world outside the thinker was, of course, erroneous. For common sense could hardly treat 'things' as merely 'sensations' artificially grouped together in space, each 'thing' being a complex of a number of sensations having relation to similar complexes. It held rather that the successive appearances of things were related in time, in such a way that they could be supposed to reveal a single object able to endure in spite of surface changes, and to manifest the identity of its sensory 'qualities.' Similarly, the succession of ideas within the mind was for it supported by the inward unity of the soul within which they arose. Moreover, Hume's analysis made havoc of all idea, of 'causation.' If every sensation was a separate being, how was it to be connected with any other in any regular or necessary connection? Two events related as 'cause' and 'effect' must be a myth.

These subversive consequences of his theory Hume did not conceal, though he did not push his mental 'atomism' to its logical extreme. When he defined material objects as 'coloured points disposed in a certain order,' he was in fact admitting space as a relating factor; when he spoke of the succession of impressions and ideas in experience, he was tacitly assuming that what was apprehended was not a bare succession of sensations, but also the fact that they were succeeding one another, and so allowing a sense of temporal relation. But further than this he refused to go. The idea of a continuous self was fantastic. There was nothing beneath the ideas to connect them. The notion of causal connection was equally chimerical. Each sensation was distinct and existed in its own right. It could therefore occur alone. There was nothing to link together the distinct impressions. Hence necessary connection in events could not be more than a fiction of the mind based on expectation of customary sequences; how the mind he had described as non-existent could form an expectation or observe a sequence was calmly left a mystery.

Hume, then, seemed to leave to his successors in philosophy a task of synthesis. He had tumbled the soul off her high watch-tower, but how to combine her shattered fragments again into a working unity he declined to say. He saw the sceptical implications of his analysis, but professed himself unable to suggest a remedy.

He had, however, made the embarrassments of the theory of knowledge sufficiently clear for Kant, his most important successor, to hit upon the most obvious palliative, and in the Critique of Pure Reason Kant set himself to patch up Hume's analysis. Experience as it came through the channels of sense, he admitted Hume had analysed correctly; it was 'a manifold,' a whirl of separate sensations. But these per se could not yield knowledge. They must be made to cohere, and the way to do this he had found. The mind on to which they fell was equipped with a complicated apparatus of faculties which could organize the chaotic manifold of sense and turn it into the connected world which common sense and science recognize. First it views the data of sense in the light of its own 'pure intuitions,' and, lo! they are seen to be in Space and Time; then it solidifies them with its own 'categories,' which turn them into 'substances' and 'causes' and endow them with all the attributes required to sustain that status; finally it refers them all to a Transcendental Ego, which is not, indeed, a soul, but sufficiently like one to provide something that can admire the creative synthesis of 'mind as such.'

Had Hume lived to read Kant's Critique, he would probably have jeered at the vain complications of Kant's transcendental machinery, and made it clear that between the primary manifold of sensation and the first constructions of the intellect there still yawns a gulf which Kant's laboured explanations nowhere bridge.

Why does the chaotic 'matter' of sensations submit itself so tamely to the forming of the mind? How can the a priori necessities of thought, which are the 'presuppositions' of the complexities Kant loved, operate upon so alien a stuff as the sensations are assumed to be? And, after all, was not Kant a bit premature in proclaiming the finality of his analysis and of his refutation of empiricism for all time? The searching question, Why should the future resemble the past? had received no answer, and so might not the mind itself, with all its categories, be susceptible to change? Was it certain that the miracle whereby the data presented to our faculties conformed to them would be a standing one? Had not Kant himself as good as admitted that our faculties might distort reality instead of making it intelligible?

The truth is that at this point Kant is open to a charge against which the assumptions he shared with Hume admit of no defence. Hume had been the first to discover that we are in the habit of trying to rationalize our sense-data by putting ideal constructions upon them, though he had abstained from sanctifying the practice by a hideous jargon of technical terminology. But this way of eking out the facts only seemed to him to falsify them. Truth in his view was to be reached by accepting with docility the sensations given from without. To set to work to 'imagine' connections between them, and to claim for them a higher truth, had seemed to him an outrage. What right, then, had Kant to legitimate the mind's impudence in tampering with sensations? Was not every a priori form an 'imagination,' and a vain one at that?

To these objections the Kantian school have never found an answer. They have simply repeated Kant's phrases about the necessary 'presuppositions' which were to be added to Hume's data. The English psychologists (the Mills, Bain, etc.) exhibited a similar fidelity. They never accepted the a priori, but relied on 'the association of ideas' to build up a mind out of isolated sensations. But was this expedient really thinkable? For if all 'sensations' or qualities are separate entities, how can the addition of more 'distinct existences' of the same sort really bind them together? If in 'the cat is upon the wall,' 'upon' is a distinct entity which has to relate 'cat' and 'wall,' what is to connect 'cat' with 'upon' and 'upon' with 'wall'? The atomizing method carried to its logical extreme demands that not only 'sensations' but also 'thoughts' should be essentially disconnected, and then, of course, no thinking can cohere.

Psychology, then, had worked itself to a breakdown by accepting the 'sensationalistic' analysis offered by Hume, and dragged philosophy with it. Yet the escape was as easy as the egg of Columbus to the insight of genius. William James had merely to invert the problem. Instead of assuming with Hume that because some experiences seemed to attest the presence of distinct objects, all connections were illusory and all experience must ultimately consist of psychical atoms, James had merely to maintain that this separation was secondary and artificial, and that experience was initially a continuum. Once this is pointed out, the fact is obvious. The stream of experience no doubt contains what it is afterwards possible to single out as 'sensations,' but it presents them also as connected by 'relations.' Moreover, the 'sensations' or 'qualities' and their 'relations' exhibit the immediate indiscerptible unity of a fluid rather than a succession of flashes. Temporal and spatial relations with all the connections they sustain are perceived just as directly as what we come to distinguish as the 'things' in them. 'Consciousness,' James insists, 'does not appear to itself chopped up in bits,' and 'we ought to say a feeling of and, a feeling of if, a feeling of but, and a feeling of by, quite as readily as we say a feeling of blue or a feeling of cold. All things in experience naturally 'compenetrate,' to use a phrase of Bergson's; they are distinct and they are united at the same time.

The great crux in Hume is thus seen to be illusory. Immediate experience does not require 'synthesis': it calls for 'analysis.' It is not a jigsaw puzzle, to be pieced together without glue: it is a confused whole which has to be divided and set in order for clear thinking. Hume's mistake was to have started from experience as partly analysed by common sense, and not from the flux as given. His 'sensations' were the qualities already analysed out of the flux; he took these selections for the whole and neglected the other less obvious features in it—viz., the relations which floated them.

Thus the puzzle 'How do "relations" relate?' received its solution in this new account of experience. Philosophers are puzzled by this question because they confuse percepts with concepts. Percepts are given in relation; but concepts, being ideal dissections of the perceptual flux, are discontinuous terms which have to be related by an act of thought, because they were made for this very purpose of distinction. Thus the eye sees cats sitting upon walls, as parts of a rural landscape, and without the sharp distinctions which exist between the concepts 'cat,' 'upon,' 'wall.' These ideas were meant to disconnect 'the cat' in thought from the site it sat upon. Thought, then, has made the 'atomism' it professed to find. It has only to unmake it, and to allow the distinctions it held apart to merge again into the stream of change.

All Hume's problems, therefore, are unreal, and those of his apriorist critics are doubly removed from reality. The whole conception of philosophy as aiming at uniting disjointed data in a higher synthesis runs counter to the real movement, which aims at the analysis of a given whole. The real question about causation is not how events can be connected causally, but why are certain antecedents preferred and dissected out and entitled 'causes.' So the 'self' is not one (undiscoverable) item imagined to keep in order a host of other such items. Any given moment of a consciousness is just the mass of its 'sensations,' but these are consciously the heirs of its history and connected with a past which is remembered. No Transcendental Ego could do more to support the process of experience than is achieved by 'a stream of consciousness which carries its own past along.' Here, then, is the straight way James desiderated, a critical philosophy which goes, not 'through' the complexities of Kantism, but leaves them on one side as superfluous 'curios.'

But there remains an even more important deduction from the new psychology. Hume had been convicted of error in selecting those elements of the flux which served his purpose and neglecting the rest. But this mistake might reveal the important fact that all analysis was a choice, and inspired by volitions. A mind that analyses cannot but be active in handling its experience. It manipulates it to serve its ends. It emphasizes only those portions of the flux which seem to it important. In a better and fairer analysis than Hume's these features will persist. It, too, would be a product of selection, of a selection depending on its maker's preferences. As James showed, the distinction between 'dreams' and 'realities,' between 'things' and 'illusions,' results only from the differential values we attach to the parts of the flux according as they seem important or interesting to us or not. The volitional contribution is all-pervasive in our thinking. And once this volitional interference with 'pure perception' is shown to be indispensable, it must be allowed to be legitimate. Nor can this approval of our interference be restricted to selections. It must be extended to additions. Just as we can select factors from 'the given' to construct 'reality,' we can add hypotheses to it to make it 'intelligible.' We can claim the right of causal analysis, and assume that our dissections have laid bare the inner springs of the connection of events. Moreover, to the 'real world which our choice has built out of the chaos of 'appearances' we may hypothetically add 'infernal' and 'heavenly' regions.^[B] Both are transformations of 'the given' by the will, but, like the postulate of causal series, experience may confirm them. Kant's a priori activity of the mind may thus in a sense supply an answer to Hume—but only in a voluntaristic philosophy which would probably have seemed too bold both to him and to Hume.

There can be no doubt that we do not approach the data of perception in an attitude of quiescent resignation. Our desires and needs equip us with assumptions and 'first principles,' which originate from within, not from without. But how precisely should this mental contribution to knowledge be conceived? In the last chapter of his Psychology James suggested that the mind's organization is essentially biological. It has evolved according to sound Darwinian principles, and in so doing the fittest of its 'variations' have survived. But were these variations quite fortuitous? May they not have been purposive responses to the stimulation of environment? Can logic have been invented like saws and ships for purposes of human service? These are some of the stimulating questions which James's work in Psychology has suggested.

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