(2.) _The Dialectic._—The pure reason has always its dialectics, since it belongs to the nature of the reason to demand the unconditioned for the given conditioned. Hence also the practical reason seeks an unconditioned highest good for that conditioned good after which man strives. What is this highest good? If we understand by the highest good the fundamental condition of all other goods, then it is virtue. But virtue is not the perfect good, since the finite reason as sensitive stands in need also of happiness. Hence the highest good is only perfect when the highest happiness is joined to the highest virtue. The question now arises: what is the relation of these two elements of the highest good to each other? Are they analytically or synthetically connected together? The former would be affirmed by most of the ancients, especially by the Greek moral philosophers. We might allow with the Stoics, that happiness is contained as an accidental element in virtue, or, with the Epicureans, that virtue is contained as an accidental element in happiness. The Stoics said: to be conscious of one’s virtue is happiness; the Epicureans said: to be conscious of the maxims leading one to happiness is virtue. But, says Kant, an analytic connection between these two conceptions is not possible, since they are wholly different in kind. Consequently there can be between them only a synthetic unity, and this unity more closely scanned is seen to be a causal one, so that the one element is cause, and the other effect. Such a relation must be regarded as its highest good by the practical reason, whose thesis must therefore be: virtue and happiness must be bound together in a correspondent degree as cause and effect. But this thesis is all thwarted by the actual fact. Neither of the two is the direct cause of the other. Neither is the striving after happiness a moving spring to virtue, nor is virtue the efficient cause of happiness. Hence the antithesis: virtue and happiness do not necessarily correspond, and are not universally connected as cause and effect. The critical solution of this antinomy Kant finds in distinguishing between the sensible and the intelligible world. In the world of sense, virtue and happiness do not, it is true, correspond; but the reason as _noumenon_ is also a citizen of a supersensible world, where the counter-strife between virtue and happiness has no place. In this supersensible world virtue is always adequate to happiness, and when man passes over into this he may look for the actualization of the highest good. But the highest good has, as already remarked, two elements, (1) highest virtue, (2) highest happiness. The actualization demanded for the first of these elements postulates the _immortality of the soul_, and for the second, _the existence of God_.