The point of this latter formulation is to stress that not...

The point of this latter formulation is to stress that not only must I be able to will that the precept in question should be recognized as a law universally, but I must also be able to will that it should be acted on universally- in the appropriate circumstances. The sense of “be able to” and “can” in these formulations is equivalent to “can without inconsistency,” the demand for consistency being part of the demand for rationality in a law that men prescribe to themselves as rational beings.

Kant’s most helpful example is that of promise keeping. Suppose that I am tempted to break a promise. The precept upon…