I argue that a Kantian inspired investigation into animal morality is both a plausible and coherent research program. To show that such an investigation is possible, I argue that philosophers, such as Korsgaard, who argue that reason demarcates nonhuman animals from the domain of moral beings are equivocating in their use of the term ‘rationality’. Kant certainly regards rationality as necessary for moral responsibility from a practical standpoint, but his distinction between the noumenal and phenomenal means that he can only establish it as a marker for morality from a theoretical standpoint. This means that when it comes to evaluating the moral capabilities of others, rationality can be neither necessary nor sufficient for morality, leaving open the possibility of other empirical markers for moral responsibility. I argue that the higher faculties, character, implicit knowledge of universality, and antecedent practical pleasures (which provide a way to distinguish between morally motivated behaviour and other types of socially motivated behaviour) can all serve as empirical markers for morality. There is empirical evidence that at least some animals have conceptual capabilities and therefore the empirical marker of the higher faculties. In addition, there is suggestive evidence that merits further investigation for the other three markers. While this will not provide a definitive answer on whether animals are capable of acting morally, it will provide a Kantian outlook that can be used to evaluate empirical and philosophical work on animal morality.