Spencer considered The Principles of Ethics to be his finest work. In volume I he covers the data of ethics, the inductions of ethics, and the ethics of individual life. In the second volume he covers the ethics of social life (or justice), negative beneficence, positive beneficence, and a number of topics in several appendices (such as Kant’s theory of rights, land ownership, and animal rights). In the large section on “Justice” he discusses property rights, free exchange, free speech, the rights of women and children, and the nature of the state. His formula for justice is summed up in these words: “Every man is free to do that which he wills, provided he infringes not the equal freedom of any other man.”
"Absolute and Relative Ethics
99. As applied to ethics, the word “absolute” will by many be supposed to imply principles of right conduct that exist out of relation to life as conditioned on the earth–out of relation to time and place, and independent of the universe as now visible to us–"eternal” principles, as they are called. Those, however, who recall the doctrine set forth in First Principles, will hesitate to put this interpretation on the word. Right, as we can think it, necessitates the thought of not right, or wrong, for its correlative; and hence, to ascribe rightness to the acts of the Power manifested through phenomena, is to assume the possibility that wrong acts may be committed by this Power. But how come there to exist, apart from this Power, conditions of such kind that subordination of its acts to them makes them right and insubordination wrong? How can Unconditioned Being be subject to conditions beyond itself?"
Herbert Spencer (27 April 1820 – 8 December 1903) was an English philosopher, biologist, anthropologist, sociologist, and prominent classical liberal political theorist of the Victorian era.
Spencer developed an all-embracing conception of evolution as the progressive development of the physical world, biological organisms, the human mind, and human culture and societies. He was "an enthusiastic exponent of evolution" and even "wrote about evolution before Darwin did." As a polymath, he contributed to a wide range of subjects, including ethics, religion, anthropology, economics, political theory, philosophy, literature, biology, sociology, and psychology. During his lifetime he achieved tremendous authority, mainly in English-speaking academia. "The only other English philosopher to have achieved anything like such widespread popularity was Bertrand Russell, and that was in the 20th century." Spencer was "the single most famous European intellectual in the closing decades of the nineteenth century" but his influence declined sharply after 1900; "Who now reads Spencer?" asked Talcott Parsons in 1937.
Spencer is best known for coining the expression "survival of the fittest", which he did in Principles of Biology (1864), after reading Charles Darwin's On the Origin of Species. This term strongly suggests natural selection, yet as Spencer extended evolution into realms of sociology and ethics, he also made use of Lamarckism.