Hume Studies

Hume Studies Volume XXVI, Number 2, November 2000, pp. 291-303 A Symposium on David Owen, Hume's Reason Owen on Humean Reason DON GARRETT David Owen begins his marvelous and extremely valuable new book, Hume's Reason, by describing the task he has set himself: "to explore Hume's account of reason and its associated modes of reasoning: demonstrative and probable ."1 This is an especially important task because, as Owen remarks, many of the most famous problems that Hume discusses and the positions that he advocates are couched in terms of reason: whether probable reasoning or causal inference is founded on reason, scepticism with regard to reason, reason and the passions, whether moral distinctions are based on reason. To understand what Hume has to say about these issues, we must understand what his account of reason and reasoning is. (HR 1) It is one of Owen's guiding themes that we can only understand Hume's account of reason and reasoning, in turn, if we see it in the context of the nonformal conceptions of reasoning that Descartes and Locke developed in reaction to the formalism of syllogistic logic. To summarize briefly, both Descartes and Locke rejected syllogistic logic as an artificial contrivance, a contrivance that captures no deep feature of actual human reasoning and is accordingly of little use for its improvement. Their own theories of reasoning emphasize the perception of relations among ideas linked in a chain or series. Thus, Descartes begins with the notion of an intuition, defined as "the indubitable conception Don Garrett is Professor of Philosophy, University of North Carolina, Chapel Hill, CB #3125, Chapel Hill, NC 27599, USA. e-mail: Don Garrett@unc.edu 292 Don Garrett of a clear and attentive mind which proceeds solely from the light of reason" (Rules for the Direction of the Mind, rule 3).2 Single intuitions are not themselves pieces of reasoning, for Descartes, but they are the elements from which reasonings are composed: the reasonings that he calls "deductions" (i.e., demonstrative reasonings) occur when the mind moves through a chain of connected intuitions. Locke famously defines knowledge (strictly so-called) as the "Perception of the Agreement or Disagreement of two Ideas."3 He conceives of intuition as the immediate perception of such agreement or disagreement; and he conceives of demonstrative reasoning as the mediated perception of such agreement or disagreement through the use of a chain of intermediate ideas (called "proofs"), ideas whose agreements or disagreements with their neighbors in the chain can be perceived by intuition. As Owen emphasizes, Locke also conceives of probable reasoning (which results in "assent" or "opinion" rather than knowledge) as a process of using intermediate ideas; but in the case of probable reasoning, the mind is said to perceive only the probable agreement or disagreementbetween two ideas (or, alternatively, the probability of agreement or disagreement between them) by the intervention of proofs, in accordance with what Locke calls the two grounds of probability—namely, testimony and conformity to past experience. As Owen explains, both Descartes's and Locke's conceptions of reasoning are non-formal because they treat the logical force of a piece of reasoning not as a result of the abstract form of the propositions that it contains but rather as a result of the specific content of the ideas that it relates and connects. An understanding of the prevalence of anti-formalism in early modern philosophy is, as Owen says, crucial to understanding Hume's treatment of reason—and, I would add, of many other aspects of early modern philosophy as well. For example, it helps to explain why the explicitly labeled "demonstrations " in Spinoza's Ethics are so rarely formally valid—a fact that has frustrated careful readers as far back as Leibniz. Leibniz, of course, had confidence in and eagerly promoted his own formal conception of logic and reasoning. But for Spinoza, formal validity was simply not a goal: he believed that his demonstrations succeeded not in virtue of the forms of their component propositions but rather in virtue of the sheer intellectual power of the ideas that they expressed. After an introductory chapter describing his project, Owen devotes one chapter to...