Of a Dialectic of Pure Practical Reason Generally.
Pure reason always has its dialetic, whether it is considered in its speculative or its practical employment; for it requires the absolute totality of the 'conditions of what is given conditioned, and this can only be found in things in themselves.But as all conceptions of things in themselves must be referred to intuitions, and with us men these can never be other than sensible and hence can never enable us to know objects as things in themselves but only as appearances, and since the unconditioned can never be found in this chain of appearances which consists only of conditioned and conditions; thus from applying this rational idea of the totality of the conditions (in other words of the unconditioned) to appearances, there arises an inevitable illusion, as if these latter were things in themselves (for in the absence of a warning critique they are always regarded as such).This illusion would never be noticed as delusive if it did not betray itself by a conflict of reason with itself, when it applies to appearances its fundamental principle of presupposing the unconditioned to everything conditioned.By this, however, reason is compelled to trace this illusion to its source, and search how it can be removed, and this can only be done by a complete critical examination of the whole pure faculty of reason; so that the antinomy of the pure reason which is manifest in its dialectic is in fact the most beneficial error into which human reason could ever have fallen, since it at last drives us to search for the key to escape from this labyrinth; and when this key is found, it further discovers that which we did not seek but yet had need of, namely, a view into a higher and an immutable order of things, in which we even now are, and in which we are thereby enabled by definite precepts to continue to live according to the highest dictates of reason.
It may be seen in detail in the Critique of Pure Reason how in its speculative employment this natural dialectic is to be solved, and how the error which arises from a very natural illusion may be guarded against.But reason in its practical use is not a whit better off.
As pure practical reason, it likewise seeks to find the unconditioned for the practically conditioned (which rests on inclinations and natural wants), and this is not as the determining principle of the will, but even when this is given (in the moral law) it seeks the unconditioned totality of the object of pure practical reason under the name of the summum bonum.