This dissertation investigates the issue of our moral duties to animals in the context of Kantian moral philosophy. Kantian arguments promise a fundamental and neutral justification of moral duties. Kantians traditionally hold that rational capacities that only humans seem to possess are necessary for moral status. This dissertation challenges this view. It is argued that if Kantian arguments justify duties to others at all, they also justify duties to animals. The first part of the dissertation argues that the Kantian view of the nature and justification of moral duty does not necessarily imply that we have duties to only those who can act morally (moral agents). Moral duties are regarded as categorical requirements, which the agent has to...