Leff is not simply concluding that there is no basis for human rights without God. He is also pointing out (as are Dershowitz and Dworkin, in their own way) that despite the fact that we can’t justify or ground human rights in a world without God, we still know they exist. Leff is not just speaking generically, but personally. Without God he can’t justify moral obligation, and yet he can’t not know it exists.
