3. Comparing how ethical traditions perform in Prisoner’s Dilemmas, against Tit-For-Tat, the best current strategy, shows: Rationalists do worse than the Golden Ruled. And Jewish norms beat Christian ethics. 4. So-called rationalists, dominated by dire untrusting logic, produce no cooperation. Golden Ruled players cooperate, thus beating rationalists. But Christian turning-the-other-cheek is exploitable (as Machiavelli and Nietzsche complained). Old Testament eye-for-an-eye is more Tit-For-Tat-like, provided forgiveness follows (however divine, forgiveness can be evolutionarily adaptive). 5. A Tit-For-Tat-like “Golden Punishment Rule” enables cooperation by preventing viable exploitation (likely applying to any game structure). But punishment that prevents profitable cheating must also avoid escalating revenge (e.g., hunter ga - http://bigthink.com/errors-we-live-by/moral-sciences-are-back