I. LEGAL POSITIVISM AND JOINTLY INTENTIONAL ACTION

Shapiro asks: “[W]hat ultimately makes it the case that a particular legal system has a particular authority structure?” (p. 388).1. This is a revised version of my response to Scott Shapiro’s Law, Plans, and Practical Reason address at the Yale Workshop on Participation and Commitment in Law, Politics, and Morality (October, 2001). Parenthetical page references are to Shapiro’s paper on p. 387 in this issue. “The legal positivist answer,” Shapiro notes, “would not point to a moral fact but rather to a social fact.” In the case Shapiro highlights, for example, the legal “positivist would argue that it is simply true by legal convention that the United States Constitution is the law of the United States” (p. 388). Shapiro aims at developing a novel version of this answer. On his view, the determinants of legal authority are certain structures of intentions and plans embedded in jointly intentional activities in which relevant legal officials are engaged. The problem of legal authority is in part a problem in the philosophy of social action.2. Shapiro is not alone in taking some such tack. Both Jules Coleman and Christopher Kutz, in part under Shapiro’s influence, have also pursued related ideas. Coleman, THE PRACTICE OF PRINCIPLE (Oxford, 2001), see lecture 7; Kutz, The Judicial Community, 11 PHILOSOPHICAL ISSUES 442-469 (2001). Coleman appeals to a strong form of shared activity, namely shared cooperative activity; Kutz appeals to a rather weak form of collective activity. The jointly intentional activity to which Shapiro appeals is in a middle ground here.