The concept of a law of nature has a central place in most comprehensive reflections on the history and philosophy of science. To confine attention here only to the systematic, philosophical aspect, the very aim of science (at least as the latter has been understood since roughly the Renaissance) has been widely held to be the discovery of empirical laws.¹ Again, the concept of law has been appealed to from a wide variety of viewpoints in the analysis of notions such as explanation, confirmation, and subjunctive conditionals.