Laws of nature have long puzzled philosophers. What distinguishes laws from facts about the world that do not rise to the level of laws? How can laws be contingent and nevertheless necessary? In what sense are the laws necessary like the broadly logical truths, yet not as necessary as those truths? What are the “lawmakers”: the facts in virtue of which the laws are laws? This book offers provocative and original answers to these questions. It argues that laws are distinguished by their necessity, which is grounded in primitive subjunctive facts (expressed by counterfactual conditionals). This ... More

Laws of nature have long puzzled philosophers. What distinguishes laws from facts about the world that do not rise to the level of laws? How can laws be contingent and nevertheless necessary? In what sense are the laws necessary like the broadly logical truths, yet not as necessary as those truths? What are the “lawmakers”: the facts in virtue of which the laws are laws? This book offers provocative and original answers to these questions. It argues that laws are distinguished by their necessity, which is grounded in primitive subjunctive facts (expressed by counterfactual conditionals). This view avoids the notorious circularity afflicting the view that the laws are the truths that would still have held had things been different in any fashion that is logically consistent with … the laws! While recognizing that natural necessity is distinct from logical, metaphysical, and mathematical necessity, the book explains how natural necessity constitutes a species of the same genus as those other varieties of necessity. The book discusses the relation between laws and objective chances, the completeness of the laws of physics, and the laws' immutability, as well as meta-laws such as the symmetry principles so prominent in contemporary physics. It is argued that David Lewis's Humean approach to law fails to do justice the laws' necessity, and that scientific essentialist approaches fail to accommodate the way certain laws transcend the details of others.