Chapter 4 contends with the Dialectic of the Teleological Power of Judgment and the discursivity of the understanding. It argues that a discursive understanding must think of the empirical world as ordered by an ideal system of universal concepts, which takes the form of a complete hierarchical taxonomy: from the most general empirical concepts to ever more specific concepts. It argues further that the assumption of a comprehensive hierarchy of concepts determining the sensibly given is Kant’s way of talking about the objective order of nature. Only the complete but unattainable determination of the sensibly given by a complete system of concepts can ground the claims to objectivity made in determinative judgments. Kant ultimately thinks of such a system and its concepts as not merely descriptive but as causally informative and thus explanatory as well. It is a transcendental condition of empirical experience and knowledge, which follows from the fact that we are discursive creatures in pursuit of objective knowledge. An important consequence is that empirical knowledge claims are always revisable and indeed defeasible. A further very important argument shows that the part-to-whole or mechanistic form of physical explanation is also grounded in the discursivity of our understanding.