Rothbard, Long, and Hoppe provide alternative defenses of praxeology. Rothbard champions an essentialist position. Therefore, the view held by representatives as well as by critics of the Austrian School and according to which the two most influential praxeologists, Mises and Rothbard, at the end of the day share similar epistemological positions is rejected. What is more, a conventionalist defense of praxeology passes Rothbard's criteria for a fundamental axiom, whereas his own essentialist arguments fail to do so. Nominalism, a subjective value theory, and methodological individualism are incoherent with essentialism. Menger's and Mises' nominalist conceptual analysis is contrasted with Wieser's twofold essentialist position.