The third formulation of the Categorical Imperative rarely receives the attention devoted to its predecessors. This paper aims to develop a naturalistic approach to morality inspired by Kant’s conception of moral agents as legislating in a Kingdom of Ends. Positions derived from the third formulation, John Rawls’s Kantian Constructivism and T. M. Scanlon’s Contractualism, cleave closely to Kant in idealising the process of legislation. For Rawls, the citizens of the Kantian Reich can be reduced to one, a representative of all, (...) who deliberates behind the veil of ignorance using minimax reasoning. Scanlon includes other lawmakers, but any potential diversity among them is overridden by trans­historical canons of reason. By contrast, I view morality as developing historically through the interactions among people with different views and conflicting aims. The task of moral theory is to construct an appropriate methodology to govern their deliberations. My naturalised Kant takes the first steps. Morality arises from the recognition of problematic situations, identified first by listening to the complaints of actual people, by judging whether they are warranted, and by seeking to amend them when the warrant is confirmed. Societies (and individuals) make moral progress when they deliberate (or simulate deliberations) in accordance with three norms. All those potentially affected should be included; the best available information should be used; and participants should aim for an outcome all can accept. How far is naturalised Kant from the great philosopher? I leave the answer to the scholars. (shrink)