Conventionalists about promising believe that it is wrong to break a promise because the promisor takes advantage of a useful social convention only to fail to do his part in maintaining it. Anti-conventionalists claim that the wrong of breaking a promise has nothing essentially to do with a social convention. Anti-conventionalists are right that the social convention is not necessary to explain the wrong of breaking most promises. But conventionalists are right that the convention plays an essential role in any (...) satisfactory account of promising. A new conventionalism can explain this by appealing to special features of social conventions. Two of these special features have important implications for any moral requirements they mediate, such as the requirement to keep one's promises and the moral requirements attached to social or occupational roles. First, these requirements will not depend on features of a situation that are inaccessible to typical participants in the convention. Second, these requirements often cannot be tailored to fit the overly unusual circumstances of participants. (shrink)