Somewhere near the heart of much recent liberal political theory is the claim that if the state restricts an agent's liberty, its restrictions should have some rationale that is defensible to each of those whose liberty is constrained. Liberals are committed to “the requirement that all aspects of the social should either be made acceptable or be capable of being made acceptable to every last individual.” In a pluralistic culture, there are many claims which are particularly controversial, many about which we expect “reasonable disagreement.” If we are to enjoy consensus regarding state restrictions, citizens should not support coercive policies on such controversial grounds. If, for example, some coercive policy is passed by popular referendum, and if its supporters have no reason to vote for the policy other than their religious convictions, then, given that reasonable, informed people reject religious belief, the policy in question lacks public justification. Given the liberal view that coercive policies should be defensible to all those affected by them, conscientious citizens should restrain themselves from supporting (or rejecting) policies on the basis of excessively controversial grounds. Principles of restraint specify both the types of grounds on the basis of which citizens may appropriately support a given policy and the types of grounds on which citizens may not properly rely.