Duncan (1973) viewed Marx as a champion of socialism, and J.S. Mill as a champion of liberalism. But this interpretation is not particularly persuasive, because Mill’s liberalism is compatible with certain types of socialism, for example, Fourierism. In addition, Mill located liberty as an essential part of human happiness, so far as it does not allow some persons to harm others. In Mill, both liberalism and socialism are based on social utility, i.e. utilitarianism, in a compatible and orderly manner.