The last abstraction which it becomes the duty of philosophy to remove is the abstraction from the knowing subject which is made by all the sciences, including, as we shall see, the science of psychology. The sciences, one and all, deal with a world of objects, but the ultimate fact as we know it is the existence of an object for a subject. Subject-object, knowledge, or, more widely, self-consciousness with its implicates—this unity in duality is the ultimate aspect which reality presents. It has generally been considered, therefore, as constituting in a special sense the problem of philosophy. Philosophy may be said to be the explica tion of what is involved in this relation, or, in Kantian phraseology, a theory of its possibility. Any would-be theory of the universe which makes its central fact impossible stands self-condemned. On the other hand, a sufficient analysis here may be expected to yield us a statement of the reality of things in its last terms, and thus to shed a light backwards upon the true nature of our sub ordinate conceptions.
to the psychologist, it is best spoken of by an unambiguous name, and for this there seems none better than Intellection. We may then say that psychology is occupied with the natural function of Intellection, seeking to discover its laws and distinguishing its various modes (perception, representative imagination, conception, etc.) according to the various circumstances in which the laws are found at work. Philosophy, on the other hand, is theory of Knowledge (as that which is known)."—"Psychology and Phil osophy," Mind (1883), pp. i 5, 16.
The confusion of these two points of view has led, and still leads, to serious philosophical misconception. It is hardly an exaggeration to say that, in the English school since Hume, psychology superseded properly philosophical inquiry. And we find even a thinker with a wider horizon like Sir W. Hamilton encouraging the confusion by speaking of "psychology or meta physics," while his lectures on metaphysics are mainly taken up with what belongs in the strictest sense to psychology proper, with an occasional excursus (as in the theory of perception) into epistemology. The distinction between psychology and theory of knowledge was first clearly made by Kant, who repeatedly in sisted that the Critique of Pure Reason was not to be taken as a psychological inquiry. He defined his problem as the quid juris or the question of the validity of knowledge, not its quid facti or the laws of the empirical genesis and evolution of intellection (to use Croom Robertson's phraseology). Since Kant, philosophy has chiefly taken the form of theory of knowledge or of a criticism of experience. Not, indeed, a preliminary criticism of our faculties or conceptions such as Kant himself proposed to institute, in order to determine the limits of their application; such a criticism ab extra of the nature of our experience is essentially a thing im possible. The only criticism which can be applied in such a case is the immanent criticism which the conceptions or categories exercise upon one another. The organized criticism of these con ceptions is really nothing more than the full explication of what they mean and of what experience in its full nature or notion is. This constitutes the theory of knowledge in the only tenable sense of the term, and it lays down, in Kantian language, the conditions of the possibility of experience. These conditions are the con ditions of knowledge as such, or, as it may be put, of objective consciousness—of a self-consciousness of a world of objects and through them conscious of itself. The inquiry is, therefore, transcendental in its nature, and does not entangle us in any de cision as to the conditions of the genesis of such consciousness in the individual. When we inquire into subjective conditions we are thinking of facts causing other facts. But the transcendental con ditions are not causes or even factors of knowledge; they are the statement of its idea. Hence the dispute between evolutionist and transcendentalist rests, in general, on an ignoratio elenchi; for the history of the genesis of an idea does not contain an answer to— though it may throw light on—the philosophical question of its truth or validity. Speaking of this transcendental consciousness, Kant goes so far as to say that it is not of the slightest conse quence "whether the idea of it be clear or obscure (in empirical consciousness), no, not even whether it really exists or not. But the possibility of the logical form of all knowledge rests on its relation to this apperception as a faculty or potentiality" (Werke, ed. Hartenstein, iii. 578 note).