 Public systems can be formal or informal. To say a public system is informal is to say that it has no authoritative judges and no decision procedure that provides a unique guide to action in all situations, or that resolves all disagreements. To say that a public system is formal is to say that it has one or both of these things (Gert 2005: 9). Professional basketball is a formal public system; all the players know that what the referees call a foul determines what is a foul. Pickup basketball is an informal public system. The existence of persistent moral disagreements shows that morality is most plausibly regarded as an informal public system. This is true even for such moral theories as the Divine Command theory and act utilitarianism, inasmuch as there are no authoritative judges of God’s will, or of which act will maximize utility, and there are no decision procedures for determining these things (Scanlon 2011: 261–2). When persistent moral disagreement is recognized, those who understand that morality is an informal public system admit that how one should act is morally unresolvable, and if some resolution is required, the political or legal system can be used to resolve it. These formal systems have the means to provide unique guides, but they do not provide the uniquely correct moral guide to the action that should be performed.