Volume 7, 2000
The Ideas of the Enlightenment and Their Legacy
The Psychologism of Hume and Quine Compared
Concentrating on the legacy of David Hume, I discuss the impact of his psychologism on his two most important sharp distinctions: (1) between statements about the relations of ideas and those about matters of fact; and (2) between what is and what ought to be. I argue that his concept of relations of ideas is subject to difficulties like those attending the concept of synonymy in twentieth-century discussions, and also that his psychologism should lead him to say that (1) is not a sharp distinction. I then raise the more difficult question of whether Hume would have said, as Quine does, that normative epistemology is an empirical science but that normative ethics is not. Finally, I discuss the difficulty of presenting naturalistic support for the claim that a scientific theory ought to predict successfully, be comparatively simple, and respect older truths in some degree.