Born in Windsor, Connecticut, on December 1, 1847, Christine Ladd grew up there, in New York City, and, following the death of her mother in 1860, in Portsmouth, New Hampshire. She attended schools in those places and in 1865, after two years╒ attendance, graduated first in her class from the Wesleyan Academy in Wilbraham, Massachusetts. She then entered Vassar College. She left after a year, taught school for a year, and then returned for a second year and received her degree in 1869. At Vassar, Maria Mitchell had interested her in astronomy, from which she moved on to physics. For the next nine years she taught science in a succession of secondary schools while continuing on her own the study of mathematics.
In 1878 she applied for admission to the graduate program at Johns Hopkins University. The school was not then open to women, but a mathematics professor who had read some of her articles in the British Educational Times arranged for her to be admitted as a special student and even to receive a fellowship. By the time her fellowship expired in 1882 she had qualified for a Ph.D., but the university would not award her the degree. In August 1882 she married Fabian Franklin, a young mathematics professor. The next year her paper on ╥The Algebra of Logic,╙ in which she developed a method for reducing all syllogisms to a single formula comprising an ╥antilogism╙ or ╥inconsistent triad,╙ was published in a volume of Studies in Logic by Members of the Johns Hopkins University, whose chief contributor was Charles Sanders Peirce.
From about 1886 Ladd-Franklin devoted much time to the study of vision, in particular the problems of binocular vision and color vision. During a year, 1891╨1892, in Germany she studied with G. E. Mƒller at GÜttingen and carried on experimental work in the Berlin laboratory of Hermann von Helmholtz. At the International Congress of Psychology in London in 1892 she presented her theory of color vision, which avoided the principal defects of those of her German mentors while introducing a plausible evolutionary mechanism to explain the rise of color perception. The Ladd-Franklin theory was for many years a leading contender in the field, and its originator, always an eager controversialist, warmly promoted it. She later served as associate editor for logic and philosophy of J. M. Baldwin╒s three-volume Dictionary of Philosophy and Psychology, 1901╨1905, and from 1904 to 1909 she was a lecturer in psychology and logic at Johns Hopkins. In 1910 she and her husband, who had turned to journalism, moved to New York City. There she lectured on logic and psychology at Columbia University, and from 1914 to 1927 she held formal appointment as a lecturer in psychology at Columbia. She continued to conduct research and published her last paper in 1926, at the age of seventy-nine. In that year Johns Hopkins at last awarded her a Ph.D. Her collected papers appeared as Colour and Colour Theories in 1929. She was a frequent speaker at scientific congresses and an effective advocate of greater academic opportunities for women. She died in New York City on March 5, 1930.
