||Utilitarianism is the moral doctrine according to which an agent's action is right in so far as it produces at least as much surplus welfare for the aggregate of sentient beings as any other action the agent could have performed in her situation. Its most important and influential proponents include John Stuart Mill, Henry Sidgwick, Derek Parfit, Shelly Kagan, and Julia Driver, each of whom provides the view with a unique formulation and defence. Utilitarianism forms the basis of much moral reasoning about practical moral problems, especially in the work of R. M. Hare, Peter Singer, Laura Purdy, and Julian Savulescu. It has a rich and detailed history. The view thrived in the nineteenth century. Critics of the view contend that it cannot accommodate our intuitions about the moral importance of justice and individual rights, that it is too demanding and that its commitment to impartiality alienates us from certain of the most important human relationships (e.g., friendship). It serves as an important rival to all forms of deontology on the one hand and to the ethics of virtue on the other.