The lawfulness of nature is a central theme in Kant’s critical philosophy. Kant distinguishes between a general lawfulness entailed by a priori conditions of possible experience and the particular causal laws of nature discovered in the empirical sciences. The focus on the latter topic led to several different interpretations of Kant’s account of particular laws. Two leading interpretations are the systematicity and the essentialist accounts. These two interpretations differ in the type of question they take Kant to answer in his account of the laws of nature. The systematicity account provides a methodological-epistemological account for the regularities that can be justifiably considered as laws of nature. On the other hand, the essentialist account explicates what it is to be a law of nature in terms of metaphysical explanatory grounds. While the interpretations are different in nature, there is textual evidence for both. 

In this paper, I explain the two interpretations and reconcile them. I argue that Kant’s account of the nature of scientific inquiry encompasses a single norm of explanation in which the systematicity and necessity of the laws of nature are interdependent. This norm is expressed in metaphysical concepts, such as real essences, powers, and above all the regulative idea of God which throughout Kant’s writing has a role of grounding the unity and necessity of the laws of nature. Thus, I argue that both accounts share an epistemic status as regulative ideas which I interpret as expressing rational norms of scientific inquiry.

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