Why is it Rational to Believe Scientific Theories are True?

Abstract

Alan Musgrave is one of the foremost contemporary defenders of scientific realism. He is also one of the leading exponents of Karl Popper’s critical rationalist philosophy. In this paper, my main focus will be on Musgrave’s realism. However, I will emphasize epistemological aspects of realism. This will lead me to address aspects of his critical rationalism as well. Musgrave is both a scientific realist and a commonsense realist. ‘Scientific realism,’ he says, ‘is a form of realism’ (1999, p. 132). And realism is committed to the commonsense realist belief ‘that there is a real world outside of us and largely independent of us’ (1999, p. 132). ‘There is,’ Musgrave adds, ‘a continuity between common sense and science’ (1999, p. 132). But while science may lead to occasional revision and refinement of common sense, ‘it does not show that it is root-and-branch mistaken’ (1999, p. 133; cf. 1996, p. 23). The real world postulated by common sense is the reality that science seeks to explain. This world does not depend on human belief or experience. Nor is it relative to conceptual scheme, theoretical background or mode of description (1999, pp. 52, 173, 180 ff). For Musgrave, though, realism is not just a thesis about reality. It is also a thesis about truth. Musgrave takes the aim of science to be truth. He ‘subscribe[s] to the old-fashioned idea that scientific realism ... says that the aim of a scientific inquiry is to discover the truth about the matter inquired into’ (1996, p. 19; cf. 1999, p. 52). Scientific theories are taken at face-value as genuine assertions about the world, the truth or falsity of which depends on the way the world really is (1996, p. 26). Musgrave understands truth in the classic correspondence sense that he takes to have been defined by Tarski. A theory or statement is true just in case the world is the