Henry Sidgwick (; 31 May 1838 – 28 August 1900) was an English utilitarian philosopher and economist and is best known in philosophy for his utilitarian treatise The Methods of Ethics. His work in economics has also had a lasting influence.
He was the Knightbridge Professor of Moral Philosophy at the University of Cambridge from 1883 until his death. He was one of the founders and first president of the Society for Psychical Research and a member of the Metaphysical Society and promoted the higher education of women.
In 1875, with Millicent Garrett Fawcett, he co-founded Newnham College, a women-only constituent college of the University of Cambridge. It was the second Cambridge college to admit women, after Girton College.
In 1856 Sidgwick joined the Cambridge Apostles intellectual secret society.
Henry Sidgwick was born at Skipton in Yorkshire, where his father, the Reverend W. Sidgwick (died 1841), was headmaster of the local grammar school, Ermysted's Grammar School. Henry's mother was Mary Sidgwick, née Crofts (1807–79).
Henry Sidgwick was educated at Rugby (where his cousin, subsequently his brother-in-law, Edward White Benson, later Archbishop of Canterbury, was a master), and at Trinity College, Cambridge. While at Trinity, Sidgwick became a member of the Cambridge Apostles. In 1859, he was senior classic, 33rd wrangler, chancellor's medallist and Craven scholar. In the same year, he was elected to a fellowship at Trinity and soon afterwards he became a lecturer in classics there, a post he held for ten years. The Sidgwick Site, home to several of the university's arts and humanities faculties, is named after him.
In 1869, he exchanged his lectureship in classics for one in moral philosophy, a subject to which he had been turning his attention. In the same year, deciding that he could no longer in good conscience declare himself a member of the Church of England, he resigned his fellowship. He retained his lectureship and in 1881 he was elected an honorary fellow. In 1874 he published The Methods of Ethics (6th ed. 1901, containing emendations written just before his death), by common consent a major work, which made his reputation outside the university. John Rawls called it the "first truly academic work in moral theory, modern in both method and spirit".
In 1875, he was appointed praelector on moral and political philosophy at Trinity, and in 1883 he was elected Knightbridge Professor of Philosophy. In 1885, the religious test having been removed, his college once more elected him to a fellowship on the foundation.
Besides his lecturing and literary labours, Sidgwick took an active part in the business of the university and in many forms of social and philanthropic work. He was a member of the General Board of Studies from its foundation in 1882 to 1899; he was also a member of the Council of the Senate of the Indian Civil Service Board and the Local Examinations and Lectures Syndicate and chairman of the Special Board for Moral Science. While at Cambridge Sidgwick taught a young Bertrand Russell.
A 2004 biography of Sidgwick by Bart Schultz sought to establish that Sidgwick was a lifelong homosexual, but it is unknown whether he ever consummated his inclinations. According to the biographer, Sidgwick struggled internally throughout his life with issues of hypocrisy and openness in connection with his own forbidden desires.
He was one of the founders and first president of the Society for Psychical Research, and was a member of the Metaphysical Society.
He also promoted the higher education of women. He helped to start the higher local examinations for women, and the lectures held at Cambridge in preparation for these. It was at his suggestion and with his help that Anne Clough opened a house of residence for students, which developed into Newnham College, Cambridge. When, in 1880, the North Hall was added, Sidgwick lived there for two years. His wife became principal of the college after Clough's death in 1892, and they lived there for the rest of his life. During this whole period, Sidgwick took the deepest interest in the welfare of the college. In politics, he was a liberal and became a Liberal Unionist (a party that later effectively merged with the Conservative party) in 1886.
In 1892 Sidgwick was the president of the second International Congress of Experimental Psychology and delivered the opening address. From the first twelve such international congresses, the International Union of Psychological Science eventually emerged.
Early in 1900 he was forced by ill-health to resign his professorship, and died a few months later. Sidgwick, who died an agnostic, is buried in Terling All Saints Churchyard, Terling, Essex, with his wife.
Sidgwick summarizes his position in ethics as utilitarianism "on an Intuitional basis". This reflects, and disputes, the rivalry then felt among British philosophers between the philosophies of utilitarianism and ethical intuitionism, which is illustrated, for example, by John Stuart Mill's criticism of ethical intuitionism in the first chapter of his book Utilitarianism.
Sidgwick developed this position due to his dissatisfaction with an inconsistency in Jeremy Bentham and John Stuart Mill's utilitarianism, between what he labels "psychological hedonism" and "ethical hedonism". Psychological hedonism states that everyone always will do what is in their self-interest, whereas ethical hedonism states that everyone ought to do what is in the general interest. Sidgwick believed neither Bentham nor Mill had an adequate answer as to how the prescription that someone ought to sacrifice their own interest to the general interest could have any force, given they combined that prescription with the claim that everyone will in fact always pursue their own individual interest. Ethical intuitions, such as those argued for by philosophers such as William Whewell, could, according to Sidgwick, provide the missing force for such normative claims.
For Sidgwick, ethics is about which actions are objectively right. Our knowledge of right and wrong arises from common-sense morality, which lacks a coherent principle at its core. The task of philosophy in general and ethics in particular is not so much to create new knowledge but to systematize existing knowledge. Sidgwick tries to achieve this by formulating methods of ethics, which he defines as rational procedures "for determining right conduct in any particular case". He identifies three methods: intuitionism, which involves various independently valid moral principles to determine what ought to be done, and two forms of hedonism, in which rightness only depends on the pleasure and pain following from the action. Hedonism is subdivided into egoistic hedonism, which only takes the agent's own well-being into account, and universal hedonism or utilitarianism, which is concerned with everyone's well-being.
As Sidgwick sees it, one of the central issues of ethics is whether these three methods can be harmonized with each other. Sidgwick argues that this is possible for intuitionism and utilitarianism. But a full success of this project is impossible since egoism, which he considers as equally rational, cannot be reconciled with utilitarianism unless religious assumptions are introduced. Such assumptions, for example, the existence of a personal God who rewards and punishes the agent in the afterlife, could reconcile egoism and utilitarianism. But without them, we have to admit a "dualism of practical reason" that constitutes a "fundamental contradiction" in our moral consciousness.