Parfit’s response to this line of argument leads him to make a claim that is perhaps even bolder than his defense of objectivism in ethics. He considers three leading theories about what we ought to do – one deriving from Kant, one from the social-contract tradition of Hobbes, Locke, Rousseau, and the contemporary philosophers John Rawls and T.M. Scanlon, and one from Bentham’s utilitarianism – and argues that the Kantian and social-contract theories must be revised in order to be defensible.