It will be sufficient to cite two passages from the second Critique to demonstrate the extent of Kant's eventual implicit rejection of his attempt to justify the moral law in Groundwork III and yet also to bring out the difficulty of pinning down exactly how he thought of his new approach to the issue of its justification. At CPR 31 he says of the "Fundamental Law of Pure Practical Reason", which he formulates now as "So act that the maxim of your will could always hold at the same time as a principle establishing universal law" (the FUL) that The consciousness of this fundamental law may be called a fact of reason, since one cannot ferret it out from antecedent data of reason, such as the consciousness of freedom (for this is not antecedently given) and since it forces itself upon us as a synthetic proposition a priori based on no pure or empirical intuition.