[C]ritics have complained that contractarians fail to provide any good reason for thinking that acts prohibited by the norms agreed on by the hypothetical contractors must be wrong. It would be absurd, they argue, to suggest that this is because hypothetical contracts (that is, contracts that one has not in fact made but would have made under certain circumstances) are somehow morally binding. Contractarian constructivism is clearly not committed to such an absurd view. Although it makes the wrongness of lying a consequence of the fact that lying would be prohibited by the norms agreed on by the contractors, this is not because an obligation to refrain from lying is created by such an agreement in the way that promises create obligations. Rather, the wrongness of lying (like the wrongness of breaking a promise) is a consequence of this agreement simply in the sense that being prohibited by such an agreement is what its moral wrongness consists in.
Ronald Milo, ‘Contractarian Constructivism’, The Journal of Philosophy, vol. 92, no. 4 (April, 1995), p. 196
Until the 1970s, utilitarianism held a dominant position in the practical moral philosophy of the English-speaking world. Since that time, it has had a serious rival in contractualism, a, ethical theory that was relaunched into modern thinking in 1971 by John Rawls’s Theory of Justice. There were even reports of utilitarianism’s imminent death. But utilitarianism is now in a vigorous and healthy state. It is responding to familiar objections. It is facing up to new problems such as the ethics of population. It has revitalized its foundation with new arguments. It has radically changed its conception of human wellbeing. It remains a credible moral theory.
John Broome, ‘Modern Utilitarianism’, in Peter Newman (ed.), The New Palgrave Dictionary of Economics and the Law, London, 1998, p. 656
Surely the partisan of utility cannot be charged with the sins of social contract. A dose of Bentham is the best cure for anyone tempted by the vision of asocial monads giving contractual shape to their natural rights.
Bruce Ackerman, Social Justice in the Liberal State, New Haven, 1980, p. 100