In a striking and convincing comment on Kant's view of autonomy, Thomas Hill observed some twenty-five years ago that ‘Autonomy is a central concept in contemporary moral debates as well as in the discussion of Kant; but the only thing that seems completely clear about autonomy in these contexts is that it means different things to different writers.’ Until I read this remark, I had assumed – in the face of considerable textual evidence to the contrary! – that Kant's discussions of autonomy deal with some variant of the topics discussed in contemporary writing on autonomy.

Contemporary views of autonomy see it as some form of individual independence, but disagree about which sort of independence it requires. Views range from existentialist or quasi-existentialist conceptions of autonomy, that identify it with mere, sheer independence in choosing and acting, to a wide range of positions that see autonomy as independence in choosing and acting that meets the demands of one or another conception of rationality. Although Kant too assumes both that agents are capable of independence (they can choose and refuse freely) and that they are rational, his claims about autonomy introduce very different considerations.

The textual evidence for the negative claim that Kant does not identify autonomy with any version of individual independence is abundant. In What Is Enlightenment? – possibly his most popular discussion of autonomy – Kant identifies it with a distinctive conception of the public use of reason (WE 8:33–42). In Groundwork of the Metaphysics of Morals he introduces the Formula of Autonomy as a version of the Categorical Imperative that articulates ‘the idea of the will of every rational being as a will giving universal law’, and claims ‘that the above principle of autonomy is the sole principle of morals can well be shown’ (G 4:440). In the Critique of Practical Reason he asserts that ‘the moral law expresses nothing other than the autonomy of pure practical reason’ (CPrR 5:33). In the Conflict of the Faculties he states that ‘the power to judge autonomously – that is freely (according to principles of thought in general) – is called reason’ (CF 7:27). In these and many other passages Kant links autonomy with reason rather than with independence. He neither construes autonomy merely as a form of individual independence, nor speaks of autonomous persons or selves.