 For Gaus, then, parties will not accept every instrumentally rational bargain. They also know that public discourse will not resolve their disagreements. And a universalizing approach will yield multiple eligible social arrangements; universalizing strategies are indeterminate. Gaus appeals to social evolution to produce convergence on an eligible understanding, which would otherwise be indeterminate. When society reaches an undefeated agreement, it achieves public justification. Each party sees no other way to secure social cooperation. Public reason combines with a sociological thesis: spontaneous order processes can converge on norms. No one foresees or constructs the justified principle or rule. But all have reason to accept the outcome of such a process.