Reflective Judgment and the Purposiveness of Nature is the first chapter of Henry E. Allison's book, "Kant's Theory of Taste and The Critique of Judgement." The chapter explains how Immanuel Kant establishes the faculty of judgement as a transcendental principle by grounding it as a required component for a person's creation of concepts, rules, and principles that universally apply to experience.

In Kant's philosophy judgement is a faculty that contributes to the functioning of two other faculties, reason and understanding. Kant posited it as a transcendental principle because he realized that it would be needed in order for these other two faculties to function. From the point of view of the first critique of the The Critique of Aesthetic Judgement, it doesn't seem that judgement can be posited as its own a priori principle. Unlike the other a priori principles, the principle of judgement lacks schemata, which are a specification of conditions under which a pure concept can be applied to the raw and undetermined data of sense experience. Since the faculty of judgement is concerned with determining whether a specific empirical state of affairs falls or does not fall under a certain concept, it's "arbitrary" choice of self-application is not bound by the "specification of conditions" or schemata.

Despite the lack of schemata, Kant relies on a different strategy to accomplish the same goal. He manages to raise the status of judgement to an a priori principle by carving out a distinction between the determinative and reflective functions of the principle of judgement. Judgement is defined as being determinative for cases in which it determines the underlying concept that should apply to empirical sense data. In such cases, it tests whether a certain principle, law, or rule can be applied to this sense data. Reflective judgement, however, does not test concepts but generates them. It generates concepts for sense experience by moving from the particular empirical presentations of sense experiences to universal rules that can conceptualize these presentations. Determinative judgement does not attempt to create concepts by reflection on presentations of sense experiences but attemtps to apply pre-determined already-available concepts to sense data.

Before the determinative judgement can have access to a ready-set of concepts that it can use to subsume the sense experience under universal rules, these concepts must have been already established by reflective judgement. This implication is what provides Kant with the impetus for grounding reflective judgement as a transcendental principle. The crux of his argument is that the way that concepts, laws, and principles are established so that they are consciously available to the mind is via the reflective judgement that turns the presentation of a purely empirical world without concepts into a conceptual one by deriving the missing concepts by the movement of the particular from the universal. Section Five of the Second Introduction of the Critique of Judgement with the heading "The Principle of the Formal Purposiveness of Nature is a Transcendental Principle of Judgment" makes that point that sense data of nature is so constructed that, regardless of whether it may be chaotic, unorganized, and senseless when considered outside of man's perspective and his faculties,it must conform to the principles, laws, and rules generated by the human mind.

However, in order for these concepts and principles to be arrived at, reflective judgment that compares the similarities of "objects" of sense experience must derive the universal laws by observing the particular.(Objects is mentioned in quotes because comparison operates on a pre-linguistic stage where it does not think of objects as objects. At that stage, nature is just one big undefined something.) That all trees have trunks and leaves is an obvious truth that takes the reflective principle of judgment to establish. The concept of a tree comes to the human mind via observation of commonalities and the positing of a principle. First one observes that many trees and their common properties of branches, leaves, and trunks. Second, one posits the concept of a tree. The derived concepts possess functional validity but there maybe different variations on the same concept. The classification of languages into linguistic groups or animal species into genuses may produce differing conceptual patterns based on differering observation and or collection of data.