 Cohen’s increased clarity about critical idealism emerged in part from work on the history of philosophy he did in the 1870s and early 1880s. He presents his view of that history in both The Principle of the Infinitesimal Method and a long introduction he added to the second edition of Kant’s Theory of Experience. As Cohen sees it, Plato and Leibniz play roles in the development of critical idealism that are second only to Kant’s. Like Kant, both sought to understand mathematics as paradigms of knowledge in general. Further, as Cohen argued in his 1878 essay “Plato’s Doctrine of Ideas and Mathematics,” Plato anticipated Kant in maintaining that the objects of our thought are explained by appeal to “ideas” (which Cohen, employing his characteristic form of philosophical charity, identified with Kantian a priori laws) (Edel 1988, Ch. 4). In contrast with this Platonic-rationalist antecedent to critical idealism, Cohen argues, stands an Aristotelian-empiricist tradition. Members of this uncritical tradition believe, in one way or another, that we must explain the objects of our thought by appeal to objects that exist independently of the mind.