Before proceeding to the normative half of this study to examine whether law actually has moral authority, this chapter briefly summarizes the conclusions of Part I by indicating how they bear on certain familiar issues in legal theory. Three distinct but related questions dominate discussions about the nature of law. Two of these questions have long-standing pedigrees as critical paths to a better understanding of the concept; the third question, a more recent arrival on the scene, is a close cousin of the first two and shows signs of becoming equally central to the current debate. The three questions are: (1) what do we mean by legal “obligation”?; (2) what is the connection between law and morality?; and (3) what is the connection between law and certainty?

The Meaning of “Legal Obligation”

Moral philosophers usually distinguish between what one ought to do and what one is obligated to do. Obligations, it is usually said, are more important or more serious than mere oughts. Though there is disagreement about exactly how to model this difference in force, the suggestion that obligation is more serious has nothing to do with the fact that oughts can be used in nonmoral contexts as well as moral ones. For even when moral oughts are the focus, it is usually thought that to say one ought to do something falls short in terms of significance from saying that one has an obligation to do the same.