Section 59

§ 59.

At the beginning of this remark I used the image of a boundary to establish the limits of reason with regard to the use appropriate to it. The world of sense contains only appearances, which are not things in themselves; the understanding must therefore assume the latter, noumena, precisely because it cognizes the objects of experience as mere appearances. Both are comprehended together in our reason, and the question is: how does reason proceed to bound the understanding with regard to both fields? Experience, which contains everything belonging to the world of sense, does not bound itself: from every conditioned thing it always reaches only another conditioned thing. What is to bound it must lie entirely outside it, and this is the field of pure beings of the understanding. But for us this is an empty space insofar as the determination of the nature of these beings is concerned; and to this extent, if dogmatically determinate concepts are intended, we cannot go beyond the field of possible experience. Yet since a boundary is itself something positive, belonging both to what is within it and to the space lying outside a given totality, there is indeed an actual positive cognition in which reason shares merely by extending itself to this boundary, though without attempting to go beyond it. For there reason finds before it an empty space in which it can indeed think forms for things, but no things themselves. Yet the bounding of the field of experience by something otherwise unknown to it is still a cognition that remains to reason from this standpoint. Through this, reason is neither confined within the world of sense nor wandering fancifully outside it, but, as befits knowledge of the boundary, restricts itself solely to the relation of what lies outside it to what is contained within.

Natural theology is such a concept on the boundary of human reason, where reason sees itself compelled to look out toward the idea of a supreme being—and in a practical relation also toward that of an intelligible world—not to determine anything with regard to this mere being of the understanding, and thus outside the world of sense, but only to guide its own use within that world according to principles of the greatest possible unity, both theoretical and practical. For this purpose it employs the world's relation to an independent reason as the cause of all these connections, not thereby merely to invent a being, but, since outside the world of sense there must necessarily be something that only the pure understanding thinks, to determine this something only in such a way, though admittedly solely by analogy.

In this way our earlier proposition, the result of the whole Critique, remains: "that reason, through all its a priori principles, never teaches us anything more than objects of possible experience alone, and even of these nothing more than can be cognized in experience." But this restriction does not prevent reason from leading us to the objective boundary of experience, namely its relation to something that is not itself an object of experience but must nevertheless be the supreme ground of all experience. Yet it teaches us nothing about this something in itself, but only in relation to reason's own complete use, directed toward the highest purposes, in the field of possible experience. This, however, is also all the benefit one can reasonably even wish for here, and with which one has cause to be satisfied.

§ 59.

At the start of this remark, I used the image of a boundary to establish reason's limitations regarding its appropriate use. The world of sense contains only appearances, which are not things in themselves. Precisely because the understanding recognizes objects of experience as mere appearances, it must therefore assume things in themselves, or noumena. Our reason encompasses both together. The question is: how does reason go about setting boundaries for the understanding with respect to both fields? Experience contains everything belonging to the world of sense, but it does not set its own boundaries. From anything conditioned, it reaches only something else that is conditioned. What is to bound it must lie entirely outside it. This is the field of pure beings of the understanding. But for us this is an empty space insofar as the determination of those beings' nature is concerned. Insofar as we seek dogmatically determinate concepts, then, we cannot go beyond the field of possible experience. Yet a boundary is itself something positive. It belongs both to what lies within it and to the space outside a given totality. So reason does gain actual positive cognition simply by extending itself to this boundary. But it must not try to go beyond the boundary, since it finds an empty space before it there. In that space it can think forms for things, but no things themselves. Still, at this standpoint reason retains knowledge of the bounding of the field of experience by something otherwise unknown to it. Through this knowledge, reason is neither shut up within the world of sense nor lost in fantasies outside it. Instead, as knowledge of the boundary requires, it restricts itself solely to the relation of what lies outside the boundary to what is contained within it.

Natural theology is a concept of this kind on the boundary of human reason. Reason finds itself compelled to look beyond to the idea of a supreme being—and, in a practical respect, also to the idea of an intelligible world. It does not do so to determine anything about this mere being of the understanding, and thus anything outside the world of sense. It does so only to guide its own use within that world according to principles of the greatest possible unity, both theoretical and practical. For this purpose, it uses that world's relation to an independent reason as the cause of all these connections. In doing so, it does not simply invent a being for itself. Something that only the pure understanding thinks must necessarily be found outside the world of sense. Reason determines this something only in that way, though admittedly only by analogy.

Our proposition above, the result of the whole Critique, therefore remains: “Through all its a priori principles, reason never teaches us anything more than objects of possible experience, nor anything more about these than can be known in experience.” But this restriction does not prevent reason from leading us to the objective boundary of experience: its relation to something that is not itself an object of experience, but must nevertheless be the highest ground of all experience. Reason teaches us nothing about this something in itself. It teaches us only in relation to its own complete use, directed toward the highest purposes, within the field of possible experience. But that is also all the benefit we could reasonably even wish for here, and we have reason to be satisfied with it.