Lafargue, Paul (pôl läfärgˈ) [key], 1842–1911, French socialist, b. Cuba; son-in-law of Karl Marx. With Jules Guesde he helped found a Marxist socialist party in France. His many writings, which were influential in other countries, include The Religion of Capital (1887, tr. 1894) and The Evolution of Property from Savagery to Civilization (1891, tr. 1894).