Locke
Society has the right to change the state if it doesn’t fulfil the social contract. No one, including the state, should harm another.
J.S. Mill
Individual sovereignty. Harm principle. He warned against the “despotism of custom”, this is where individuals/state is guided purely by public opinion; instead of this there should be “experiments in living”. Ideas must be subjected to free debate.
Rawls
Rational individuals would choose to create a society and live in one that improved the conditions of the poorest members. Individuals should be able to start anywhere in society and, due to equal opportunity, succeed.