According to Kant, there is some doctrine, which he sometimes calls 'empirical realism,' such that it was doubted by Descartes, denied by Berkeley, and endorsed by Kant himself. It may be doubted whether there really is such a doctrine or, if there is, whether it takes the form Kant seems to say it does. For instance, if empirical realism is taken as the assertion that familiar objects like tables and chairs exist, then this doctrine was neither seriously doubted by Descartes, (...) nor denied by Berkeley. If empirical realism is the view that such objects are mind-independent, then it was clearly denied by Berkeley, but was neither seriously doubted by Descartes, nor straightforwardly endorsed by Kant. Kant's assertion thus presents us with a puzzle: what might empirical realism be? The primary aim of this paper will be to reconstruct Kant's own narrative of the historical relationship between Descartes, Berkeley, and himself, in order to identify the doctrine Kant calls 'empirical realism.' I argue that the empirical realism which Descartes doubted, Berkeley denied, and Kant endorsed is the doctrine that the concept of extended substance has legitimate application. (shrink)