The structure of David’s Bloor argument for the Strong Programme (SP) in Science Studies is criticized from the philosophical perspective of anti-skeptical, scientific realism. The paper transforms the common criticism of SP—that the symmetry principle of SP implies an untenable form of cognitive relativism—into the␣clear philosophical issue of naturalism versus Platonism. It is also argued that the concrete patterns of SP’s interest-explanations and its sociological definition of knowledge involve philosophical skepticism. It is claimed, then, that the most problematic elements of SP reside primarily in philosophical skepticism. It is also claimed that this sort of criticism can be directed against other more radical, versions of constructivism in science and science education studies.