This section contains an admirable defence of the value of scepticism.
“Even poisons have their use. They serve to counteract other poisons generated in our system, and must have a place in every complete pharmacopeia. The objections against the persuasions and complacency of our purely speculative Reason arise from the very nature of Reason itself, and must therefore have their own good use and purpose, which ought not to be disdained. Why has Providence placed many things which are closely bound up with our highest interests so far beyond our reach, that we are only permitted to apprehend them in a manner lacking in clearness and subject to doubt, in such fashion that our enquiring gaze is more excited than satisfied? It is at least doubtful whether it serves any useful purpose, and whether it is not, indeed, perhaps even harmful to venture upon bold interpretations of such uncertain appearances. But there can be no manner of doubt that it is always best to grant Reason complete liberty, both of enquiry and of criticism, so that it may be without hindrance in attending to its own proper interests. These interests are no less furthered by the limitation than by the extension of its speculations; and they will always suffer when outside influences intervene to divert it from its natural path, and to constrain it by what is irrelevant to its own proper ends.”[1705] “Whenever I hear that a writer of real ability has demonstrated away the freedom of the human will, the hope of a future life, and the existence of God, I am eager to read the book, for I expect him by his talents to increase my insight into these matters.”[1706]
SECTION IV[1707]
THE DISCIPLINE OF PURE REASON IN REGARD TO ITS PROOFS[1708]
This section merely restates the general nature and requirements of transcendental proof. The exposition is much less satisfactory than that already given in the Analytic and Dialectic. The only really new factor is the distinction between apagogical and direct proof. The former may produce conviction, but cannot enable us to comprehend the grounds of the truth of our conviction. Also, outside mathematics, it is extremely dangerous to attempt to establish a thesis by showing its contradictory to be impossible.[1709] This is especially true in the sphere of our Critical enquiries, since the chief danger to be guarded against is the confounding of the subjectively necessary with the independently real. In this field of investigation it is never permissible to attempt to justify a synthetic proposition by refuting its opposite. Such seeming proofs can easily be secured, and have been the favourite weapons of dogmatic thinkers.
“Each must defend his position directly, by a legitimate proof that carries with it transcendental deduction of the grounds upon which it is itself made to rest. Only when this has been done, are we in a position to decide how far its claims allow of rational justification. If an opponent relies on subjective grounds, it is an easy matter to refute him. The dogmatist cannot, however, profit by this advantage. His own judgments are, as a rule, no less dependent upon subjective influences; and he can himself in turn be similarly cornered. But if both parties proceed by the direct method, either they will soon discover the difficulty, nay, the impossibility, of showing reason for their assertions, and will be left with no resort save to appeal to some form of prescriptive authority; or the Critique will the more easily discover the illusion to which their dogmatic procedure is due; and pure Reason will be compelled to relinquish its exaggerated pretensions in the realm of speculation, and to withdraw within the limits of its proper territory—that of practical principles.”[1710]
CHAPTER II
THE CANON[1711] OF PURE REASON
SECTION I
THE ULTIMATE END OF THE PURE USE OF OUR REASON[1712]
The problems of the existence of God, the freedom of the will, and the immortality of the soul have, Kant declares, little theoretical interest. For, as he has already argued, even if we were justified in postulating God, freedom, and immortality, they would not enable us to account for the phenomena of sense-experience, the only objects of possible knowledge. But the three problems are also connected with our practical interests, and in that reference they constitute the chief subject of metaphysical enquiry.[1713] The practical is whatever is possible through freedom; and the decision as to what we ought to do is the supreme interest of pure Reason in its highest employment.