This article examines the phenomenon of thought insertion, one of the most extreme disruptions to the standard mechanisms for self-knowledge, in the context of Kant's philosophy of mind. This juxtaposition is of interest for two reasons, aside from Kant's foundational significance for any modern work on the self. First, thought insertion presents a challenge to Kant's approach. For example, the first Critique famously held that " The 'I think' must be able to accompany all my representations " (Kant, KrV, B132). (...) Yet thought insertion raises the problem of representations which are 'mine' by many natural criteria, and yet which I am unwilling to self-ascribe. Ultimately, my argument will be that thought insertion simultaneously problematises, and yet to some degree also vindicates, the complex distinctions between activity and passivity which underlie Kant's system. Second, I argue that Kant's position contains resources that allow us to model thought insertion, and its broader implications for self-knowledge, in an interesting and distinctive manner. Kant himself held an extreme view of philosophy's competence in the study of mental disorder: in the Anthropology, he suggests that courts must refer such cases to philosophers, rather than medics (Kant, Anth, p.214). My aim is much more modest: to suggest that a Kantian treatment of thought insertion deserves consideration by both philosophers and clinicians. (shrink)