2. Among the conditions necessary to all consciousness of time is self-consciousness.

3. Self-consciousness, in turn, is itself conditioned by consciousness of objects.

4. Consciousness of objects is possible only if the categories have validity within the sphere of sense-experience.

5. Conclusion.—The empirical validity of the categories, and consequently the empirical validity of our consciousness alike of the self and of objects, must be granted as a conditio sine qua non of our consciousness of time. They are the indispensable conditions of that fundamental experience.

As above stated,[879] the preliminary stages of the subjective deduction prepare the way for the argument of the objective deduction, while the results obtained by the latter render possible the concluding steps of the former. That is to say, the objective deduction has to be intercalated midway between the opening and the concluding stages of the subjective deduction. It may also be observed that whereas the objective deduction embodies the main positive teaching of the Analytic, in that it establishes the possibility of natural science and of a metaphysics of experience, the subjective deduction is more directly concerned with the subject-matter of the Dialectic, reinforcing, as it does, the more negative consequences which follow from the teaching of the objective deduction—the impossibility of transcendent speculation. It stands in peculiarly close connection with the teaching of the section on the Paralogisms. We may now proceed to a detailed statement of the argument of the two deductions.

THE SUBJECTIVE DEDUCTION IN ITS INITIAL EMPIRICAL STAGES

In the opening of the subjective deduction Kant is careful to give due prominence to the temporal aspect of our human experience.

“...all the contents of our knowledge are ultimately subject to the formal condition of inner sense, that is, to time, as that wherein they must all be ordered, connected, and brought into relation to one another. This is a general remark which the reader must bear in mind as being a fundamental presupposition of my entire argument.”[880]

Consciousness of time is thus the starting-point of the deduction. Analysis reveals it as highly complex; and the purpose of the deduction is to discover, and, as far as may be possible, to define its various conditions. The argument can best be expounded by reference to a single concrete example—say, our experience of a series of contents, a, b, c, d, e, f, as in succession to one another and as together making up the total six. In order that such an experience may be possible the successive members of the series must be held together simultaneously before the mind. Obviously, if the earlier members dropped out of consciousness before the mind reached f, f could not be apprehended as having followed upon them. There must be a synthesis of apprehension of the successive items.

Such a synthesis of apprehension is, however, only possible through reproduction of the earlier experiences. If when the mind has passed from a to f, f is apprehended as having followed upon a, b, c, d, e, such consciousness is only possible in so far as these earlier contents are reproduced in image. Synthesis of apprehension is conditioned by synthesis of reproduction in imagination.