This paper aims to evaluate the relevance of Kant’s much discussed essentialism and mechanism for present-day philosophy of psychiatry. Kendler et al. (Psychological Medicine 41(6):1143–1150, 2011) have argued that essentialism is inadequate for conceptualizing psychiatric disorders. In this paper, I develop this argument in detail by highlighting a variety of essentialism that differs from the one rejected by Kendler et al. I show that Kant’s essentialism is not directly affected by the argument of Kendler et al. (Psychological Medicine 41(6):1143–1150, 2011), and that Kendler et al.’s (Psychological Medicine 41(6):1143–1150, 2011) argument also does not affect other essentialist positions in psychiatry. Hence, the rejection of essentialism in psychiatry needs more arguments than the one supplied by Kendler et al. Nevertheless, the study of current psychiatry also provides reasons to reject Kant’s essentialism and his transcendental project. I argue that Kant’s theory of mechanical explanation is more relevant for analyzing present-day philosophy of psychiatry, insofar as (a) modern psychiatric research into the causes of psychiatric disorders fits the mechanist paradigm, (b) Kant’s theory of mechanical explanation is importantly similar to modern theories of mechanical explanation applicable to psychiatry, such as those of Bechtel and associates, and (c) Kant’s stance that mechanism constitutes a regulative ideal points to useful arguments for the pursuit of mechanical explanations in psychiatry.
