The investigation of questions that arise from reflection upon science and scientific practice. Such questions include: what distinguishes the methods of science? Is there a clear demarcation between sciences and other disciplines, and where do we place such enquiries as history, economics, or sociology? Are scientific theories probable, or more in the nature of provisional conjectures? Can they be verified, or falsified? What distinguishes good from bad explanation? Might there be one unified science, embracing all the special sciences? For much of the 20th century these questions were pursued in a highly abstract and logical framework, it being supposed that a general logic of scientific discovery or justification might be found. However, many now take interest in a more historical, contextual, and sometimes sociological approach, in which the methods and successes of a science at a particular time are regarded less in terms of universal logical principles and procedures, and more in terms of the then available methods and paradigms, as well as the social context.

In addition to general questions of methodology, there are specific problems within particular sciences, giving rise to specialist philosophies of such subjects as biology, mathematics, and physics.