The fundamental thesis of contractarianism is that social norms must be based on the agreement of the people. Contract theorists present two different bases for this thesis. The first is the expectation that each person, who is presupposed to be a utility maximizer, reaches his highest utility level when he coordinates his actions with others according to norms both parties can voluntarily accept. But this cannot be supported, because people have conflicting and incompatible preferences. The second basis is the equality of people; that is, the recognition that people are similar beings and that none of them is superior to anyone else. Contractarians assume, on the basis of equality, that although people are different in particular abilities and talents, they have similar general capacities for comprehending human nature and the world, and the relations between these; therefore, each person can claim the equal right to judge how people ought to live and how the society should be. I think that citizens in modern democratic societies approve, or will approve after due reflection, this contractarian assumption of equality, because this is essential to endorsing our basic liberties, for example, the freedom of expression. If we regard ourselves as being equal in this respect, we have no choice but to determine social norms by agreement.