Hume on Reason

20. HUME ON REASON1 One of the main concerns of Hume's Treatise of 2 Human Nature (T) is the investigation of the role that reason plays in belief and action. On the standard interpretation , Hume is taken to argue that neither our beliefs nor our actions are determined by reason; Books I and III are thus seen as sharing a common theme: the denigration of reason's role in human affairs. Arguing for this view, Kemp Smith claims that "Hume's principle of the subordination of reason to the passions runs through his whole philosophy " , not merely through Books II and III. This interpretation of Hume's enterprise presupposes that the faculty of reason whose role in action is discussed in Book III is the same faculty which has been shown not to determine belief in Book I. In this paper I argue that a univocal reading of 'reason' and related terms like 'reasoning' throughout the Treatise has the consequence that there are major internal inconsistencies in Hume's philosophy, cannot account for some important sections of the work, and leads to misinterpretation of the nature of his overall argument. In its place I develop an interpretation which avoids these difficulties and emphasizes the radical nature of Hume's naturalism. The Argument of the Treatise Let me begin by reviewing the salient features of the main argument of the Treatise. In Book I , Hume is concerned to show that our most fundamental beliefs — e.g. , about the continued and distinct existence of object, about what we are not presently observing, and in the existence of the self — are not acquired by reason, but instead by the imagination, influenced by custom and habit. In a typical passage, he argues: Reason can never shew us the connexion of one object with another, tho' aided by experience, and the observation of their constant conjunction in all past instances. When the mind, 21. therefore, passes from the idea or impression of one object to the idea or belief of another, it is not determin'd by reason... (T92)4 In Book III, and in Book II, Part III, Section III (Of the influencing motives of the will), Hume is concerned to show that reason alone can never produce any action, or give rise to volition (T414) , and the same faculty is as incapable of preventing volition, or of disputing the preference with any passion or emotion (T414-415) . Hume uses this result in Book III, Part I, Section I, to show that the rules of morality .. .are not conclusions of our reason (T457). Proponents of the univocal reading of 'reason' would hold that the Treatise thus constitutes a continuous attack on reason, showing that it causes neither our most fundamental beliefs nor our actions and moral judgments. But if this reading were correct, Hume would fail to avail himself of an obvious and persuasive argument for the conclusion he reaches in Books II and III, and in the latter books he would contradict the results of Book I. Conflict between Book I and Books II and III If Hume did have the same faculty in mind throughout the Treatise, a strong argument to show that reason does not cause action would be available to him in Books II and III, utilizing the results he has established in Book I. The principal way in which reason would be thought to influence action is by informing us of facts about efficient means to achieve our ends and about the possible effects of actions — facts about causal relations. Since the conclusion of Book I is that judgments about causal relations do not result from reason, it follows that even if such beliefs did cause action, it would still not be the case that reason caused action. But Hume not only does not make such an argument in Books II and III, he denies one of its premises — the claim that beliefs about causal relations do not result from reason — which was the main conclusion of Book I. In the 22. later books he asserts repeatedly that reason can cause beliefs about causal relations. For example, in Book III, he says: ...reason, in a strict and philosophical...