The Normative Force of Promising

Why do promises give rise to reasons? I consider a few possibilities which do not work, then outline a more plausible explanation of the normativity of promising—that it is constitutive of the practice of promising that promise-breaking implies blame-liability and that we take blame-liability to be an undesirable thing. This view, quasi-conventionalism, provides a reduction of the normativity of promising to conventionalism about liability and instrumental normativity. The result is an account of the normativity of promising that (a) explains the particularity of promissory reasons, (b) predicts that our reasons to keep our promises are often overdetermined, and (c) provides a natural explanation of fringe-cases of promissory reasons: deathbed promises, immoral promises, conflicting promises, and promises which no one expects you to keep. Meeting these three desiderata of an account of promissory reasons gives us good reason to take quasi-conventionalism seriously. The style of explanation can be extended to account for nearly all normativity—one notable exception being instrumental normativity. Success for the clearly conventional case of promissory reasons thus makes plausible a general reduction of normativity to conventions and instrumental normativity.