Promise as Practice Reason Hanoch Sheinman Received: 27 July 2008 / Accepted: 19 August 2008 / Published online: 30 September 2008 # Springer Science + Business Media B.V. 2008 Abstract To promise someone to do something is to commit oneself to that person to do that thing, but what does that commitment consist of? Some think a promissory commitment is an obligation to do what’ s promised, and that while promising practices facilitate the creation of promissory obligations, they are not essential to them. I favor the broadly Humean view in which, when it comes to promises (and so promissory obligations), practices are of the essence. I propose the Practice Reason Account of promises, according to which a promise is basically to give oneself a self-interested practice reason to do what’ s promised. One achieves this feat by invoking self- enforcing independent practice rules thanks to which one’ s doing what’ s promised preserves one’ s promissory trust(worthiness) and promising power. However, nothing in this account supports the Hume-Rawls claim that promise-keeping or promise- breaking is right just when and because it conforms to practice rules that are justified by their good- or right-making properties. Keywords Promise . Practice . Reason . Obligation . Self-interest . Hume In this paper, I propose, explain, and defend a broadly Humean account of (what) promises (are). According to this Practice Reason Account, to promise is basically to give oneself a self-interested practice reason to do what’ s promised (by communicat- ing an intention to do so). This I recommend as an alternative to the Obligation Account, the popular view that to promise is basically to undertake an obligation to do what’ s promised (by communicating an intention to do so). On the account I favor, promises—and so promissory obligations—are essentially practice-based creatures: they presuppose practices that do not presuppose them. Synopsis The paper consists of three parts. Part 1 (Explaining Promises) situates our question—the question of the correct definition of promises—in the larger context of a Acta anal. (2008) 23:287–318 DOI 10.1007/s12136-008-0033-1 H. Sheinman (*) Rice University-MS 14, 6100 Main Street, Houston, TX 77005, USA e-mail: sheinman@rice.edu