Kantian deontology makes at least three central claims: (1) All humans are ends in themselves, (2) All humans have moral obligations, and (3) Morality (the categorical imperative) is a rational endeavor. However, the universal claims of Kantian deontology become suspect when we consider the mentally impaired who, in some cases, cannot meet the rationality requirements implicit in the categorical imperative. In this paper, I argue that Kantian deontology cannot account for the entirety of the human population lest it exclude the mentally impaired as either non-moral agents or sub-human entities. I then suggest that by adopting the paradigm of virtue ethics, we can sufficiently avoid this problem and account for the dignity and moral agency of the mentally impaired. Finally, I consider one objection to this moral picture and respond.

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