REASON AND PASSION

Hume wrote that “we speak not strictly and philosophically when we talk of the combat of passion and of reason. Reason is, and ought only to be, the slave of the passions, and can never pretend to any other office than to serve and obey them” (Treatise, Bk. II, Pt. III, Sect. III). What did he mean?

In the first place, Hume's “passions” are sometimes none too passionate. He speaks of some passions as “calm”. We would do best to speak of all “passion”, calm and otherwise, as “desire”.

In the second place, we call someone “reasonable” in part because his desires are moderate and fair-minded. But when we do, I suppose we speak not strictly and philosophically. Strictly speaking, I take it that reason is the faculty in charge of regulating belief. And so I read Hume as if he had said that belief is the slave of desire. Our actions do, or they ought to, serve our desires according to our beliefs. More precisely, taking account of the fact that both belief and desire admit of degree, and not begrudging the usual idealizations that make the topic tractable, our actions serve our subjective expected values according to our subjective degrees of belief. For short: they serve our values according to our credences.

Values and credences belong to propositions: classes of maximally specific possibilities (perhaps egocentric and tensed).