a1 Université fédérate de Santa Catarina
Ian Hacking puts forward a distinction between two kinds of scientific realism. According to scientific realism about theories, scientific theories are accepted as approximately true; according to scientific realism about unobservable entities, the theoretical terms occurring in scientific theories refer to existing, real entities. This article seeks to show that Claude Bernard's philosophy of science is a realist one about scientific theories, but anti-realist about unobservable entities. The term “fictionalism” is used here to stand for this sort of anti-realism about unobservable entities.