I recently discovered in my WordPress feed a legal philosophy blog edited by Lucas Miotto and Martin David Kelly. Their excellent blog, which is called “Legal-Phi”, contains in-depth interviews with many young legal and moral philosophers. Today, I am re-blogging their most recent interview: Ezequiel Monti (see below). Among other things, Professor Monti explains his take on Mark Greenberg’s influential “Moral Impact Theory of Law.” What role, for example, do “moral facts” play in law? How is a legal obligation similar to or different from a moral obligation? These are fascinating questions, but I won’t go into the technical details of Greenberg’s theory (or Monti’s take on that theory), except to point out an important omission that bedevils this never-ending legal-philosophical debate: the problem of “immoral promises” (see here, for instance). To borrow Professor Monti’s own example, “Suppose I promise you to wash your car. In virtue of my promise, I now have an obligation to wash your car.” Now consider a different example: A promises B to steal C’s car. Doesn’t A now have an obligation to steal C’s car? If not, why not? (Please, no answers with circular reasoning in them.)