Ladd-Franklin, Christine (1847–1930)

US psychologist and logician. In 1883 she proposed the ‘antilogism’, a syllogism concluding that if any two premises are true, the third must be false. Her experiments in psychological optics began in 1886, and she presented her theory of colour vision to the International Congress of Psychologists in London, England, in 1892. She taught at Columbia University (1910–30). Ladd-Franklin was born in Windsor, Connecticut. She studied mathematics at Johns Hopkins University, where she married faculty member Fabian Franklin in 1882.