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. 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 that Descartes doubted, Berkeley denied, and Kant endorsed is the doctrine that the concept of extended substance has legitimate application.

Phenomenalist interpretations of Kant are out of fashion. The most common complaint from anti-phenomenalist critics is that a phenomenalist reading of Kant would collapse Kantian idealism into Berkeleyan idealism. This would be unacceptable because Berkeleyan idealism is incompatible with core elements of Kant’s empirical realism. In this paper, I argue that not all phenomenalist readings threaten empirical realism. First, I distinguish several variants of phenomenalism, and then show that Berkeley’s idealism is characterized by his commitment to most of them. I then make the case that two forms of phenomenalism are consistent with Kant’s empirical realism. The comparison between Kant and Berkeley runs throughout the paper, with special emphasis on the significance of their theories of intentionality.