 Canguilhem was more interested in the biological and health sciences than Bachelard and gave great attention to the distinction between the normal and the pathological, a distinction that does not arise in physical science. For this and other reasons, in his view, we can expect no reduction of biology to physics. Canguilhem provided a more nuanced conception of obstacles and ruptures, noting, for example, that an approach such as vitalism that constitutes an obstacle in one domain of research can simultaneously play a positive role elsewhere, as in helping biological scientists to resist reductive thinking. Here we find context sensitivities and heuristic resources difficult to capture in terms of a context- and content-neutral logic of science such as the logical empiricists espoused.