Carl Gustav Hempel was born in Germany, immigrated to the United States, and became a naturalized citizen. He taught at Yale, Princeton, and Pittsburgh. Along with Sir Karl Popper and Thomas S. Kuhn, a former colleague, he would become one of the most important philosophers of science of the twentieth century. Popper exerted more influence upon natural scientists and Kuhn upon social scientists and the public alike, but Hempel's impact upon professional philosophers of science was unparalleled. His work, including the problems he addressed and the methods he employed, virtually defined the philosophy of science, not just for a few years, but for several decades.

Hempel sought solutions to philosophical problems that were not only well-supported by suitable arguments but which were also precisely formulated by means of symbolic logic. He proposed subtle and nuanced formulations of scientific philosophy and promoted the...