In our current philosophical culture, we well understand that the full meaning of the natural sciences does not lie in their theoretical and experimental contents alone. We readily admit (indeed insist) that what is conveyed by the concept of an "electron," for example, or a "gene" or a "cognitive process," needs to be elucidated within the full context of the historically developed, investigative practices — the theoretical and experimental research programs, together with the logical and epistemological assumptions — that lie behind their use. In short, we suppose that any putative scientific knowledge must be interpreted within the ongoing project of a critical philosophy of science.