 Kant appeared not to recognize the gap between the law of an autonomous rational will and the CI, but he was apparently unsatisfied with the argument establishing the CI in Groundwork III for another reason, namely, the fact that it does not prove that we really are free. In the Critique of Practical Reason, he states that it is simply a “fact of reason” (Factum der Vernunft) that our wills are bound by the CI, and he uses this to argue that our wills are autonomous. Hence, while in the Groundwork Kant relies on a dubious argument for our autonomy to establish that we are bound by the moral law, in the second Critique, he argues from the bold assertion of our being bound by the moral law to our autonomy.