One of the major philosophical problems in physical sciences is what criteria should determine how scientific theories are selected and justified in practice and whether, in describing observable physical phenomena, such theories are effectively constrained to be unique. This book studies the example of a particular theory, the S-matrix theory. The S-matrix program was initiated by Heisenberg to deal with difficulties encountered in quantum field theories in describing particular phenomena. Since then, each theory has at different times been favoured as the explanation of observed phenomena. Certainly the S-matrix theory was adequate, feasible and fertile. However, the quantum field theory interpretation is now widely accepted and the study of alternative theories is all but abandoned. By examining the philosophy which influenced the turns in this story, the author explains how an adequate and viable theory fell out of favour and concludes with a critique of different methodologies in the history of science. This book will be of value to both philosophers of science and physicists interested in the philosophical background to their field.

"...provides a compact but wide-ranging survey of the contending philosophies: and it does so in a spirit that is fair minded, clear(clear, that is, by the standards of philosophic exposition), and forebearing." American Journal of Physics

"...this book constitutes a serious endeavor in which sophisticated discussions are supported by thoroughly readable analysis of actual scientific practice. It is an impressive and important contribution, both to our historical understanding of scientific practice and to the ongoing philosophical debate about the nature of science, and advances scholarship in the philosophy of science in an important direction....Cushing's book, with its reliable treatments and impressive nontechnical summaries of technicality, is a successful effort that will help a wide audience overcome the difficulties and understand the philosophical issues involved in contemporary physics, thereby inviting them to participate in the ongoing discussions." Tian Yu Cao, Isis

"...performs a valuable and necessary service by testing theories of scientific explanation against carefully developed accounts of how complex quantitative theories develop, function, and are appraised." Edward M. MacKinnon, Foundations of Physics