This chapter provides a summary introduction to the book. It explains the central question the book addresses and why it is important. Namely, it asks why academic nuclear deterrence theory maintains that nuclear superiority does not matter, but policymakers often behave as if it does. It then provides a brief explanation of the answer to this question: the superiority-brinkmanship synthesis theory. It discusses the implications of the argument for international relations theory and for US nuclear policy. In contrast to previous scholarship, the argument of this book provides the first coherent explanation for why nuclear superiority matters even if both sides possess a secure, second-strike capability. In so doing, it helps to resolve what may be the longest-standing, intractable, and important puzzle in the scholarly study of nuclear strategy. It concludes with a description of the plan for the rest of the book.
