Afterword

The proposal that Hume woke Kant by challenging the principle of sufficient reason lets us understand why Kant saw Hume as an opponent of speculative theodicy, since speculative theodicy was grounded in that principle. It thereby also allows us to understand Kant’s turn to Rousseau, who “saved Providence,” and the turn from speculative to practical metaphysics that characterizes Kant’s critical philosophy. The difficulty people have had in understanding Kant’s account of how Hume roused him has to do with the fact that they wish to avoid his transcendental idealism, since that account implies that Hume woke him by putting him on the path to transcendental idealism. To understand the Critique, we must understand it as the “execution” of Hume’s problem understood as the problem of metaphysics.

Hume’s Attack on the “Impious Maxim” as the Hidden Spine of the Critique

Chapter 5 tests the proposal that it was Hume’s attack on the principle of sufficient reason that first interrupted Kant’s dogmatic slumber and set Kant on the path to the Critique by looking, in the Critique, for echoes of Enquiry 12.29 note (d). It finds such echoes in the Transcendental Ideal, the Postulates of Empirical Thought, the Analogies of Experience, and the Antinomy of Pure Reason. It seeks to explain how Enquiry 12.29 note (d) might have helped suggest the solution to the Antinomy, transcendental idealism. It discusses Boehm’s view that the Antinomy is a reply to Spinoza. Kant is indeed responding to Spinoza, but also to Clarke; his response to both is inspired by Hume.

Defining “The Objection of David Hume”

Chapter 2 shows that to understand Kant’s reference to “the objection of David Hume which first, many years ago, interrupted my dogmatic slumber” we must read it against the background of his earlier references to Hume’s “question” and to Hume’s “attack” on metaphysics. It breaks down Hume’s “attack” on metaphysics into three steps: a demonstration that rules out the possibility of knowing causal connection through pure concepts, and thus of knowing the principle of sufficient reason; a conclusion that the concept of cause is a bastard of the imagination; and a conclusion that there is no metaphysics. It argues that Kant’s source for this account is the Enquiry, not the Treatise, and points to the sections of the Enquiry that correspond to each step.

Introduction

The introduction investigates the literature on Kant’s awakening by Hume. It begins by considering the view, which goes back to Vaihinger and Kemp Smith, that Hume woke Kant by challenging the causal principle defended in the Second Analogy, the principle that every event has a cause. It then takes up the attempts of Kuehn and then of Gawlick and Kreimendahl, in the 1980s, to reconcile Kant’s declaration of his debt to Hume with a later assertion that it was the Antinomy that woke him. Finally, it addresses the rich literature on the topic that has developed in the present century, and in particular the views of Hatfield, Watkins, Forster, and De Pierris and Friedman.

Interpreting Hume on the Causal Principle

Chapter 4 supports by means of collateral evidence the claim that Hume woke Kant by attacking the principle of sufficient reason. First, it considers Treatise 1.3.3, though without supposing that Kant knew this text, in order to show that there, where Kemp Smith and others thought Hume was attacking the principle that every event has a cause, he was actually attacking the principle of sufficient reason. Second, it explains Hume’s lack of explicitness in the Enquiry about the fact that he was attacking the principle of sufficient reason; he avoided explicitness on this score, I argue, in order to veil his antitheological intentions. Third, it examines Sulzer’s commentary on Enquiry Section 4, which Kant surely knew well, to show that Sulzer read Section 4 as attacking the principle of sufficient reason. The fact that Kant’s contemporaries such as Sulzer and Tetens read Hume in this way makes it plausible to suppose that Kant did too.

Hume’s Attack on the Rationalist Principle of Sufficient Reason in the Enquiry

Chapter 3 investigates more precisely where in the Enquiry Kant finds Hume showing that we cannot know causal connections via pure concepts, and thus that we cannot know the principle of sufficient reason. Hume’s rejection of the principle of sufficient reason comes to a head at 4.13, and Hume returns to it at 12.29 note (d). 12.29 note (d) is directed not, as Hume pretends, against Lucretius’s principle Ex nihilo, nihil fit, but against the causal principle that Descartes, Locke, and Clarke had used to prove the existence of God. This is confirmed by reading 12.29 note (d) against the background of Bayle’s “Spinoza.” Descartes’s Ex nihilo, nihil fit is equivalent, for our purposes, to the principle of sufficient reason found in Wolff, Baumgarten, and the early Kant. The chapter addresses Michael Della Rocca’s argument that Hume failed in his attack on the principle of sufficient reason.

The Objection of David Hume and the Project of Enlightenment

Chapter 1 places Kant’s declaration about his debt to Hume against the background of the Preface to the Prolegomena as a whole. It argues that Kant sees Hume’s attack on metaphysics as a contribution to Enlightenment. Kant praises Hume by opposing his critics, like Beattie, whose invocation of common sense against Hume Kant associates with the Inquisition’s enforcement of orthodoxy via “chisel and hammer.” We must read Kant’s defense of Hume, the Preface argues, against the background of the scandal produced by Hume’s Dialogues. Kant’s evocation of Horace links the Preface with Kant’s “What Is Enlightenment?” and its motto sapere aude. It must be read alongside Hume’s attack on priestcraft in the Enquiry and in “Of the Rise and Progress of the Arts and Sciences.”