Contemporary philosophy of science combines a general study from a philosophical perspective of the methods of science, with an inquiry, again from the philosophical point of view, into foundational issues that arise in the various special sciences. Methodological philosophy of science has deep connections with issues at the center of pure philosophy. It makes use of important results, for example, in traditional epistemology, metaphysics and the philosophy of language. It also connects in various ways with other disciplines such as the history and sociology of the sciences, with pure logic, and with such branches of mathematics as probability theory. These volumes are, for the most part, devoted to readings in the methodological aspects of the philosophy of science. One volume, however, takes up the philosophical issues in the foundations of a particularly important special science, that is the issues in the foundations of theories of contemporary physics. The methodological volumes cover a number of crucial general problem areas. The first volume takes up issues in the nature of scientific explanation, and the related issues of the nature of scientific law and of the casual relation among events. The second volume explores issues in the nature and structure of scientific theories.