Legal positivism's ``separation thesis'' is usually taken in one of two ways: as an analytic claim about the nature of law – roughly, as some version of the Social Thesis; or as a substantive claim about the moral value of law – roughly, as some version of the Value Thesis. In this paper I argue that we should recognize a third kind of positivist separation thesis, one which complements, but is distinct from, positivism's analytic and moral claims. The Neutrality Thesis (...) says that the correct analytic claim about the nature of law does not by itself entail any substantive claims about the moral value of law. I give careful formulations of these three separation theses, explain the relationships between them, and sketch the role that each plays in the positivist approach to law. (shrink)