The title of this chapter presupposes that there can be scientific progress. But half a century ago Thomas Kuhn famously attacked this assumption when he claimed that all past knowledge turned out to be false, and moreover was local rather than universal. The many constructivist-relativists who followed in his wake went much farther: they held that all the objects or referents of scientific ideas, from molecules to galaxies, are social constructions, and are therefore confined to the scientific communities that make them up (e.g., Latour and Woolgar 1979).