What ought probably means, and why you can't detach it

Stephen Finlay

pp. 67-89

in: Synthese 177 (1), 2010.

Abstract

Some intuitive normative principles raise vexing ‘detaching problems’ by their failure to license modus ponens. I examine three such principles (a self-reliance principle and two different instrumental principles) and recent stategies employed to resolve their detaching problems. I show that solving these problems necessitates postulating an indefinitely large number of senses for ‘ought’. The semantics for ‘ought’ that is standard in linguistics offers a unifying strategy for solving these problems, but I argue that an alternative approach combining an end-relational theory of normativity with a comparative probabilistic semantics for ‘ought’ provides a more satisfactory solution.