Sure, but when the alternative to rationality is hope -- as in, disarm and hope that everyone else follows and doesn't lie despite having every incentive to take advantage -- rationality starts looking pretty good by comparison.

I'm all for arms reduction that maintains strategic deterrence. Everyone knows that MAD is, well, mad -- but the real question is whether it is more or less mad than the alternatives, and the leading alternative is to trust a bunch of sovereign nations to act together against their best interest, and that's even more mad than MAD.