 The sources as well as the form of Kant’s position are complex. Kant was deeply impressed by what he knew of Leibniz (many of the texts that are crucial to later understandings of Leibniz, such as “Primary Truths”, having been unknown in Kant’s times, or others, such as the New Essays on Human Understanding, having been published only when he was well into his career) and the view that space and time are phaenomena bene fundata as well as by what he knew of Hume and his view that causation is a form of thinking that we impose upon our experience rather than something we directly experience. He was more generally impressed by the empiricist argument that our knowledge of objects depends upon experience of them. However, he thought that both the Leibnizian and the Humean approaches failed to account for the possibility of synthetic a priori knowledge, that is, knowledge that goes beyond the mere analysis of concepts, that thus does more than merely unpack explicit or tacit definitions, but yet legitimately claims universal and necessary validity. But, unlike Plato, the original apriorist avant la lettre, he does not see synthetic a priori knowledge as leading to realism about objects having the features that we know a priori, nor, like Malebranche, the theological Platonist, does he see such knowledge as knowledge of the mind of God; rather, he sees it as providing the conclusive argument for the idealist aspect of his position through the premise that we can only know to be necessary and therefore universally valid the forms that we ourselves impose upon our experience. Thus precisely because we have a priori knowledge of space and time, in his view they can be only features of our own representations of things, not properties or relations of those things as they are in themselves. At the same time, even though when he wrote his main works he was not well-informed on the aporia about subjects and objects about which Hume had ultimately thrown up his arms in the Treatise, which has here been characterized as the tension in Hume between agnosticism and idealism, Kant recognized that we cannot talk about what he called appearances without conceding the real existence of subjects to which objects appear as well as the objects that appear to such subjects. Kant was thus led to what he called “transcendental idealism”, a position that combines idealism about the main forms of objects, that is, the view that we ourselves impose spatiality, temporality, substantiality, causality, and other forms upon our experience and precisely because we know these forms a priori cannot regard them as also the real forms of objects independent of ourselves, with a kind of ontological realism, the view that in some sense both our selves and our objects really do exist independently of our representations of them. Although he identifies his own “transcendental idealism” with “empirical realism” he does not want to call his own position “transcendental realism”, because for him that would be the view that objects independent of our representations do exist with the forms that we represent them as having; that is, in Kant’s terms, transcendental realism would be the view that things really are spatial and temporal independently of our representing them as such. Neither would he even be happy to call this conception of things in themselves a kind of idealism, because it is part of his position that, at least from what he calls a theoretical point of view, we cannot suppose that even our own minds are really as they appear to us, nor can we assert that the reality that ultimately underlies the appearance of minds is essentially different from the reality that ultimately underlies the appearance of bodies. Yet he remains confident that we are entitled to assert the existence of some sort of reality underlying the appearance of both minds and bodies. And to make matters even more complicated, he is confident that we can rationally believe both ourselves and God to be mental in nature from what he calls a “practical” point of view, that is, as necessary presuppositions of rationally attempting to do what morality commands. A complete characterization of Kant’s position would thus be empirical realism about space, time, causation, and the other categories, transcendental idealism about space and time but combined with realism about the existence of things in themselves, and now practical idealism about the nature of ourselves as things in themselves and the nature of God, as in both cases essentially mental or spiritual. 