Kant’s conception of the necessity of laws of nature can only be properly understood, I argue, by focussing on his development from the first edition of the Critique through the Prolegomena and Metaphysical Foundations of Natural Science to the second edition. His mature view, in particular, is that the necessity resulting from the constitutive activities of the understanding results from the successive application of the three modal categories (possibility, actuality, and necessity). I sketch out the way in which the law of universal gravitation — as explicitly discussed in both the Prolegomena and the Metaphysical Foundations — provides Kant with his central example of this procedure, and I also discuss the role of this procedure (and its central example) in the culminating sections of the B Deduction. Finally, I address the relationship between this constitutive procedure and the regulative procedures of reason and the faculty of judgement — which, in turn, sheds light on the relationship between what Kant (in the Preface to the Metaphysical Foundations) calls “general” and “special” metaphysics of nature.
Michael Friedman: Natural Laws and Natural Necessity