In this article, Husserl's theory of the structure of scientific knowledge is explicated against the background of the traditional Aristotelian concept of science. Husserl's account of the scientific status and character of the empirical sciences is then taken up in connection with Locke's statement of the problem. Against the standard criticisms of Husserl's philosophy of science as rigid and dogmatic, it is maintained that Husserl adopts something like the hypothetical-deductive model of empirical scientific rationality; furthermore, through his later theory of evidence, he introduces a strong critical component into his account of the eidetic sciences.