The PSR as a practical principle in Kantian ethics

The Principle of Sufficient Reason (PSR) is the canonical expression of the idea of reality as fundamentally rational or intelligible, such that there is always a sufficient ground or explanation for everything about which such questions can be asked. In this essay, I argue that recent attempts to rehabilitate the PSR, despite their many virtues, have not gone far enough in emphasizing the centrality of this principle within all areas of philosophy - both theoretical and practical. Thus, I hope to show that to fully appreciate the significance of the PSR, we need to attend to the role it plays in reasoning of both a theoretical and a practical sort. As we will see, this point is especially important from a Kantian perspective, where it is practical, and not theoretical reason that is the home of our deepest and most substantive commitment to a version of the PSR. Thus, for a Kantian, to understand the nature of our commitment to the PSR, we need to consider this question first and foremost from a practical perspective - or perhaps ultimately from a point of view that somehow transcends the practical-theoretical distinction itself.