Bertrand Russell

It appeared to me obvious that the happiness of mankind should be the aim of all action, and I discovered to my surprise that there were those who thought otherwise. Belief in happiness, I found, was called Utilitarianism, and was merely one among a number of ethical theories. I adhered to it after this discovery, and was rash enough to tell my grandmother that I was a utilitarian. She covered me with ridicule, and ever after submitted ethical conundrums to me, telling me to solve them on utilitarian principles. I perceived that she had no good grounds for rejecting utilitarianism, and that her opposition to it was not intellectually respectable.

Bertrand Russell, The Autobiography of Bertrand Russell: 1872-1914, London, 1967, pp. 44-45