I argue that §§15–20 of the B-Deduction contain two independent arguments for the applicability of a priori concepts, the first an argument from above, the second an argument from below. The core of the first argument is §16's explanation of our consciousness of subject-identity across self-attributions, while the focus of the second is §18's account of universality and necessity in our experience. I conclude that the B-Deduction comprises powerful strategies for establishing its intended conclusion, and that some assistance from empirical psychology might well have produced a completely successful argument.