This interpretation of Kant's problem is based upon the "transcendental deduction," and an examination of it might therefore be profitably reserved for a later article. But so much of the transcendental deduction as bears upon the point in dispute may be anticipated and readily understood. It amounts in fact to no more than this, that the pure concepts of the understanding (substance, cause, etc.) are objectively valid, because they render all experience possible, so far as its form is concerned. Or, in other words, the transcendental deduction explains ordinary experience as a complex of presentations of sense synthesized by thought. And since the deduction is the centre and essence of the critical philosophy, it is natural to see in the Critique, however otherwise Kant may have described its problem, merely an account of the forms of synthesis entering into experience and a proof of their indispensableness to it. Not the creations of reason, unassisted by experience, but reason's impregnation of experience: such would be the subject of the Critique.
It is not, it will be admitted, a happy piece of historical criticism which reaches an interpretation incompatible with the explicit statement of the text. And it has yet to be shown that a determination of the forms of synthesis entering into experience is an answer to the Kantian question, What and how can reason know without the aid of experience? Nor is it relevant to urge that an author's initial statement of his problem is always provisional, and subject to modification by the solution subsequently attained; so that we who have the end and outcome of Kant's work before us can understand its intention better than he did. The preface of a book is the last part to be written. And what is more, Kant had not only his entire work but also the opinions of the public upon it before him when he wrote the new prefatory and introductory matter for the second edition and for the Prolegomena. Yet it is precisely there that the problem is first completely crystallized in the form, How are a priori synthetic judgments possible? And when one remembers that the entire aim of the Prolegomena was to present the critical philosophy in a clear
