We may call the faculty of cognition from principles a priori, pure Reason, and the inquiry into its possibility and bounds generally the Critique of pure Reason, although by this faculty we only understand Reason in its theoretical employment, as it appears under that name in the former work; without wishing to inquire into its faculty, as practical Reason, according to its special principles. That [Critique] goes merely into our faculty of knowing things a priori, and busies itself therefore only with the cognitive faculty to the exclusion of the feeling of pleasure and pain and the faculty of desire; and of the cognitive faculties it only concerns itself with Understanding, according to its principles a priori, to the exclusion of Judgement and Reason (as faculties alike belonging to theoretical cognition), because it is found in the sequel that no other cognitive faculty but the Understanding can furnish constitutive principles of cognition a priori. The Critique, then, which sifts them all, as regards the share which each of the other faculties might pretend to have in the clear possession of knowledge from its own peculiar root, leaves nothing but what the Understanding prescribes a priori as law for nature as the complex of phenomena (whose form also is given a priori). It relegates all other pure concepts under Ideas, which are transcendent for our theoretical faculty of cognition, but are not therefore useless or to be dispensed with. For they serve as regulative principles; partly to check the dangerous pretensions of Understanding, as if (because it can furnish a priori the conditions of the possibility of all things which it can know) it had thereby confined within these bounds the possibility of all things in general; and partly to lead it to the consideration of nature according to a principle of completeness, although it can never attain to this, and thus to further the final design of all knowledge.

It was then properly the Understanding which has its special realm in the cognitive faculty, so far as it contains constitutive principles of cognition a priori, which by the Critique, comprehensively called the Critique of pure Reason, was to be placed in certain and sole possession8 against all other competitors. And so also to Reason, which contains constitutive principles a priori nowhere except simply in respect of the faculty of desire, should be assigned its place in the Critique of practical Reason.

Whether now the Judgement, which in the order of our cognitive faculties forms a mediating link between Understanding and Reason, has also principles a priori for itself; whether these are constitutive or merely regulative (thus indicating no special realm); and whether they give a rule a priori to the feeling of pleasure and pain, as the mediating link between the cognitive faculty and the faculty of desire (just as the Understanding prescribes laws a priori to the first, Reason to the second); these are the questions with which the present Critique of Judgement is concerned.

A Critique of pure Reason, i.e. of our faculty of judging a priori according to principles, would be incomplete, if the Judgement, which as a cognitive faculty also makes claim to such principles, were not treated as a particular part of it; although its principles in a system of pure Philosophy need form no particular part between the theoretical and the practical, but can be annexed when needful to one or both as occasion requires. For if such a system is one day to be completed under the general name of Metaphysic (which it is possible to achieve quite completely, and which is supremely important for the use of Reason in every reference), the soil for the edifice must be explored by Criticism as deep down as the foundation of the faculty of principles independent of experience, in order that it may sink in no part, for this would inevitably bring about the downfall of the whole.

We can easily infer from the nature of the Judgement (whose right use is so necessarily and so universally requisite, that by the name of sound Understanding nothing else but this faculty is meant), that it must be attended with great difficulties to find a principle peculiar to it; (some such it must contain a priori in itself, for otherwise it would not be set apart by the commonest Criticism as a special cognitive faculty). This principle must not be derived a priori from concepts, for these belong to the Understanding, and Judgement is only concerned with their application. It must, therefore, furnish of itself a concept, through which, properly speaking, no thing is cognised, but which only serves as a rule, though not an objective one to which it can adapt its judgement; because for this latter another faculty of Judgement would be requisite, in order to be able to distinguish whether [any given case] is or is not the case for the rule.

This perplexity about a principle (whether it is subjective or objective) presents itself mainly in those judgements that we call aesthetical, which concern the Beautiful and the Sublime of Nature or of Art. And, nevertheless, the critical investigation of a principle of Judgement in these is the most important part in a Critique of this faculty. For although they do not by themselves contribute to the knowledge of things, yet they belong to the cognitive faculty alone, and point to an immediate reference of this faculty to the feeling of pleasure or pain according to some principle a priori; without confusing this with what may be the determining ground of the faculty of desire, which has its principles a priori in concepts of Reason.—In the logical judging of nature, experience exhibits a conformity to law in things, to the understanding or to the explanation of which the general concept of the sensible does not attain; here the Judgement can only derive from itself a principle of the reference of the natural thing to the unknowable supersensible (a principle which it must only use from its own point of view for the cognition of nature). And so, though in this case such a principle a priori can and must be applied to the cognition of the beings of the world, and opens out at the same time prospects which are advantageous for the practical Reason, yet it has no immediate reference to the feeling of pleasure and pain. But this reference is precisely the puzzle in the principle of Judgement, which renders a special section for this faculty necessary in the Critique; since the logical judging according to concepts (from which an immediate inference can never be drawn to the feeling of pleasure and pain) along with their critical limitation, has at all events been capable of being appended to the theoretical part of Philosophy.

The examination of the faculty of taste, as the aesthetical Judgement, is not here planned in reference to the formation or the culture of taste (for this will take its course in the future as in the past without any such investigations), but merely in a transcendental point of view. Hence, I trust that as regards the deficiency of the former purpose it will be judged with indulgence, though in the latter point of view it must be prepared for the severest scrutiny. But I hope that the great difficulty of solving a problem so involved by nature may serve as excuse for some hardly avoidable obscurity in its solution, if only it be clearly established that the principle is correctly stated. I grant that the mode of deriving the phenomena of the Judgement from it has not all the clearness which might be rightly demanded elsewhere, viz. in the case of cognition according to concepts; but I believe that I have attained to it in the second part of this work.

Here then I end my whole critical undertaking. I shall proceed without delay to the doctrinal [part] in order to profit, as far as is possible, by the more favourable moments of my increasing years. It is obvious that in this [part] there will be no special section for the Judgement, because in respect of this faculty Criticism serves instead of Theory; but, according to the division of Philosophy (and also of pure Philosophy) into theoretical and practical, the Metaphysic of Nature and of Morals will complete the undertaking.