 Classical social contract theorists grounded political legitimacy on consent. The chief social contract theorists were Thomas Hobbes, John Locke, Jean-Jacques Rousseau, and Immanuel Kant. They had different standards of consent; the first three oscillated between an empirical and a normative standard. The empirical standard draws on actual mental states: consent justifies political power because it draws on each party’s beliefs and values. The normative standard draws on somehow rational mental states: we appeal not to what people believe and value but what they have reason to believe and value. Political power is justified when grounded in what parties ideally affirm. In the latter case, we sometimes speak of hypothetical consent as a proxy for rational justification.