Crooked Timber has a little Hume-fest going on with people sending their favorite quotes: David celebrates his 300th birthday today. I love reading Hume : I love the prose, that is - who doesn't? But much of what he says so charmingly strikes me as absurd.
It is Hume that we can thank - and when I say 'thank' I mean, of course, 'curse' - for the Belief-Desire Model of rational agency. The economists' very conception of rationality is his inheritance. You know the quotes - "reason is and ought only to be the slave of the passions"; " tis not contrary to reason to prefer the destruction of the whole world to the scratching of my little finger" yadda yadda. (Incidentally, Smith in the Theory of Moral Sentiments says, in effect, it is contrary to reason to prefer the destruction of the whole world - well it's an earthquake in China, actually- to a scratch on my finger).
But the thing is, if reason can't motivate without being filtered through some desire, we couldn't have an intellectual discussion, couldn't discuss the very question of whether practical reason is or is not purely instrumental, for example : if "discussion" means listening to and evaluating the arguments made, drawing conclusions from the evidence, changing one's view when confronted with an unanswerable objection- and so on. Reason must move me directly, e.g., to change my mind, to draw the conclusions that follow from what I believe - without any antecedent desire being necessary.
And don't get me started on is's and oughts!
I love The Dialogues on Natural Religion, I love the History of England. You can have The Treatise and the Enquiry, thanks. But I wouldn't have wanted to miss the former, so a grudging Happy Birthday, Davey.!