As a moral phenomenon, promises have long received great amounts of attention in philosophical debates within both normative ethics and metaethics. This book defends a novel trust-based form of non-reductivism about promises and promissory normativity.

There is a tension inherent in the ways in which promises feature in our ethical thought. On the one hand, that one is obligated to keep one's promises appears to be one of the most straightforward, unquestionable moral truths around. On the other hand, promissory obligation, as an obligation voluntarily incurred through a performative speech act, has appeared to many as mysterious, and thus in need of a specific explanation. This book sets out from this tension to substantially advance debates both about the nature of promises and promissory normativity, and by extension, normative powers more generally. It develops a comprehensive account of promissory normativity, the "Two-Level Trust View". This view retains the intuitive plausibility of a non-reductive account of promissory normativity, according to which the mere fact that one has validly promised is sufficient to render a breach of promise morally wrong. At the same time, it also provides a powerful and theoretically appealing value-based explanation of our promissory power, a type of explanation traditionally thought to be limited only to reductive accounts of promissory normativity.

Because You Promised will appeal to researchers and graduate students working in normative ethics and metaethics, philosophy of language, political philosophy, and philosophy of law.