 It is common to think that the intuitive contrast between is and ought marks an important gap between distinct domains, and sometimes this gap is identified as a distinction between “facts” and “values”. Thick concepts may be thought to challenge such dichotomies between facts and values (Murdoch 1970; Williams 1985: 140–5; Dancy 1995; Putnam 2002: 34–45). To avoid misunderstanding, note that an important gap can be held to exist even if values are a special kind of facts. For instance, according to so-called Hume’s Law, one cannot derive an ought from an is (Hume 1739–40: §3.1.1). Any (non-trivial) valid argument for an evaluative conclusion must somehow (perhaps implicitly) involve evaluative content in its premises. This logical or conceptual barrier can be generalized to concern various relations of reasonable inference between the non-evaluative and the evaluative. The underlying thought is that evaluative and normative statements commend things and guide action, whereas purely non-evaluative statements play no such practical role by themselves. The resulting claim that there is no reasonable (non-trivial) inference to any evaluative conclusion from any set of purely non-evaluative premises is sometimes called “the autonomy of ethics” (Rynin 1957; Prior 1960).