Click on the phrases to see them in context. The original texts by Immanuel Kant and David Hume are available from the Gutenberg Projet.

But since the moral law is binding on each individual in the use of his freedom of volition, even if others should not act in conformity with this law, neither the nature of things, nor the causality of actions and their relation to morality, determine how the consequences of these actions will be related to happiness; and the necessary connection of the hope of happiness with the unceasing endeavour to become worthy of happiness, cannot be cognized by reason, if we take nature alone for our guide.

It is plain that, if all causality in the world of sense were natural--and natural only--every event would be determined by another according to necessary laws, and that, consequently, phenomena, in so far as they determine the will, must necessitate every action as a natural effect from themselves; and thus all practical freedom would fall to the ground with the transcendental idea. But this systematic unity of ends in this world of intelligences- which, as mere nature, is only a world of sense, but, as a system of freedom of volition, may be termed an intelligible, that is, moral world (regnum gratiae)--leads inevitably also to the teleological unity of all things which constitute this great whole, according to universal natural laws--just as the unity of the former is according to universal and necessary moral laws--and unites the practical with the speculative reason. The assertor of the all-sufficiency of nature in regard to causality (transcendental Physiocracy), in opposition to the doctrine of freedom, would defend his view of the question somewhat in the following manner. That element in the question of the freedom of the will, which has for so long a time placed speculative reason in such perplexity, is properly only transcendental, and concerns the question, whether there must be held to exist a faculty of spontaneous origination of a series of successive things or states. That this antinomy is based upon a mere illusion, and that nature and freedom are at least not opposed--this was the only thing in our power to prove, and the question which it was our task to solve. The second takes no account of our desires or the means of satisfying them, and regards only the freedom of a rational being, and the necessary conditions under which alone this freedom can harmonize with the distribution of happiness according to principles.

We cannot, therefore, escape the responsibility of at least a critical solution of the questions of reason, by complaints of the limited nature of our faculties, and the seemingly humble confession that it is beyond the power of our reason to decide, whether the world has existed from all eternity or had a beginning--whether it is infinitely extended, or enclosed within certain limits--whether anything in the world is simple, or whether everything must be capable of infinite divisibility--whether freedom can originate phenomena, or whether everything is absolutely dependent on the laws and order of nature--and, finally, whether there exists a being that is completely unconditioned and necessary, or whether the existence of everything is conditioned and consequently dependent on something external to itself, and therefore in its own nature contingent.

Transcendental freedom is therefore opposed to the natural law of cause and effect, and such a conjunction of successive states in effective causes is destructive of the possibility of unity in experience and for that reason not to be found in experience--is consequently a mere fiction of thought.