orig. Christine Ladd
born Dec. 1, 1847, Windsor, Conn., U.S.
died March 5, 1930, New York, N.Y.
U.S. scientist and logician.
She fulfilled Ph.D. requirements at Johns Hopkins University in the 1880s, but, because women candidates were not recognized, she was not awarded her degree until 1926. In symbolic logic, she reduced syllogistic reasoning to an inconsistent triad with the introduction of the antilogism, a form that made the testing of deductions easier. The Ladd-Franklin theory of colour vision stressed increasing colour differentiation with evolution and assumed a photochemical model for the visual system. Her principal works are The Algebra of Logic (1883), The Nature of Color Sensation (1925), and Color and Color Theories (1929).