Kant as Ethical Naturalist: First and Second Natures in Kant's Ethics

I argue that Kant's use, in the critical ethical writings, of our nature as autonomous, rational beings (if imperfectly so) to argue against the normative authority of human nature shows Kant's ethical system to instantiate its own distinctive version of ethical naturalism. The formal structure of Kant's argument fits within ethical naturalism: our nature is what explains how we get onto and are bound by ethical norms. What changes is that Kant rejects the authority of human nature to generate these moral norms by arguing that only rational nature as free and autonomous could sanction this sort of normative grip. In order to show the viability of reading Kant as an ethical naturalist, I address two problems: 1) how to specify a Kantian first nature that is not too human, nor too formal and so empty; 2) how to specify a Kantian second nature as some settled disposition towards willing morally good actions and yet compatible with reason's autonomy.