1. PERFECTED SYSTEMATIZATION REQUIRES A RESORT TO PURPOSE

Kant holds that to understand nature properly we must understand it purposively. The human intellect, so he maintains, insists on finding a causality of purpose behind the causality of nature. The pivotal concept is that of design - in both senses of the term, order and purpose, which Kant sees as indissolubly interlocked in human thought.

Kant thus holds that the human intellect cannot rest satisfied with merely causal explanations of nature because explanations in the order of efficient causality always proceed by invoking minor premises (“conditions”) that place the case at hand within the reach of a major explanatory premise. We can never bring this process to a satisfactory conclusion - can never “find for the conditioned knowledge obtained through the understanding the unconditioned whereby its unity is completed” (CPuR, A307 = B364). And so no matter how we string them together, something will remain left out, something in principle explicable but itself still unexplained. The process of causal explanation is inherently interminable. But in the order of teleology, questions can have a stop: the quest for purposes behind purposes can come to an end in an ultimate, unmediated purpose: the regress of questions ceases, and the human mind can rest satisfied. As Kant himself puts it, purposively governed free choice “offers a point of rest to the enquiring understanding in determining the chain of [efficient] causes, conducting it to an unconditional causality which begins to act of itself” (CPuR, A447 = B475). To bring inquiry to a satisfactory conclusion we humans must accordingly go beyond or behind efficient causality - to purpose.

Kant is orthodoxly Leibnizian in his belief that while natural events always occur in line with mechanical laws, the makeup of these laws themselves is to be understood in teleological terms.