It is well known that Kant distinguishes between two kinds of self-consciousness: transcendental apperception and empirical apperception (or, approximately, inner sense). However, Kant sometimes claims that “I think,” the general expression of transcendental apperception, expresses an indeterminate empirical inner intuition (IEI), which differs in crucial ways from the empirical inner intuition produced by inner sense. Such claims undermine Kant’s conceptual framework and constitute a recalcitrant obstacle to understanding his theory of self-consciousness. This paper analyzes the relevant passages, evaluates the major (...) interpretations of IEI, revisits the notion of pure apperception, and proposes an alternative reading: IEI is a ubiquitous, nonfocal, “obscure,” and empirical inner intuition that is built into all nonintrospective conscious states. This reading can successfully account for the peculiarities of IEI, resolving a major mystery in Kant’s theory of self-consciousness. (shrink)