Postmodernism has established a significant hold in educational thought and some of the most important ideas are to be found in the writings of Michael Peters. This paper examines his postmodern stance and use of Lyotard's account of knowledge, and from a naturalist point of view raises a number of objections centred on science as a metanarrative, the unity of the empirical and the evaluative, and reason, truth and the growth of knowledge. It is concluded that postmodern epistemology, unlike naturalism, does not serve education well.