A theory of a social practice must be able to carry a certain descriptive and interpretive burden: it must be able to account for those features of the practice so central to its character that, without them, the practice would become distorted or unrecognizable as a phenomenon in the social world. A theory of jazz music needs an account of improvisation; a theory of natural science needs an account of experimentation; a theory of democracy needs an account of voting. A theory with no place for these sorts of structural or architectural features is incompetent, revisionist, or, at the limit, not a theory of the practice (of jazz, of science, of democracy) at all. As Ernest Weinrib has argued in developing a theory of private law: “Within private law’s massive complex of cases, doctrines, principles, concepts, procedures, policies, and standards,” there are “certain features” whose “systematic absence would mean the disappearance of private law as a recognizable mode of ordering” and that therefore must, “[a]t the level of theory . . . be explained or explained away.” Just so. The social theorist’s burden is either to explain her practice’s architectural features or show them to be less foundational than they seem, and thus to explain them away.