(An edited version of this paper appears in the Routledge Companion to Philosophy of Law, 2012, ed. Andrei Marmor) ARE CONTRACTS PROMISES? Seana Valentine Shiffrin Introduction: Some of what is at stake Many, perhaps most, lawyers, theorists and laypeople in the United States consider contracts to be “legally enforceable promises” (Fried 1981; Markovits 2004; Markovits 2011: 314-18; Mur- phy 2007; Shiffrin 2007; Wilkinson-Ryan and Baron 2009: 420–23). That description seems ini- tially confirmed by examples like the following. Suppose that I promise to paint your house if you promise to pay me $3,000 for doing so. By exchanging these promises, we have formed a contract and each of us is both morally and legally obliged to perform. If one of us fails to per- form, contract law empowers the other party to obtain a legal judgment and a remedy for the oth- er’s failure to keep her promise. Associated with this description of a contract as a legally binding promise is the theoreti- cal ambition to use the moral, common-sense features of promises as starting material to fashion a plausible legal theory of contracts. The thought is that if contracts have, at their foundations, the same moral relations that we describe as promises in our everyday social relations, that fact might provide the seedlings both of a justification for contract law and of a guide to the princi- ples it should follow. For example, on the justification front, this description may encourage the view that con- tract law exists to buttress the moral institution of promising, whether by facilitating the social benefits we glean from that institution; by vindicating and protecting the rights promisors trans- fer to promisees; by providing support and recognition for a valuable social relationship; or, on