kant and mendelssohn published almost simultaneously influential essays on the enlightenment. i use this historical contingency as occasion to reflect on the presuppositions and implications their views have with respect to philosophy and politics. in the first part, i compare mendelssohn's discursive strategy with that of traditional liberalism. a contradiction emerges from this contrast, which, in the second part, i interpret in kantian terms as an antinomy of modern political reason. kant's notion of "autonomy," i suggest, is an attempt to overcome this very antinomy. putting things this way allows us to better appreciate the originality of kant's defense of the free use of public reason and his contribution to the liberal tradition.