In the 19th century, the attempt to base ethical reasoning on the presumed facts about evolution. The movement is particularly associated with Spencer. The premise is that later elements in an evolutionary path are better than earlier ones; the application of this principle then requires seeing western society, laissez-faire capitalism, or some other object of approval, as more evolved than more ‘primitive’ social forms. Neither the principle nor the applications command much respect. The version of evolutionary ethics called ‘social Darwinism’ emphasizes the struggle for natural selection, and draws the conclusion that we should glorify and assist such struggle, usually by enhancing competitive and aggressive relations between people in society, or between societies themselves. More recently the relation between evolution and ethics has been re-thought in the light of biological discoveries concerning altruism and kin-selection. See also evolutionary psychology.