Susanne Katherina Langer (née Knauth) (20 December 1895 – 17 July 1985) was an American philosopher of mind and of art who was influenced by Ernst Cassirer and Alfred North Whitehead. She was one of the first women to achieve an academic career in philosophy and the first to be popularly and professionally recognized as an American philosopher. Langer is best known for her 1942 book Philosophy in a New Key.
Langer was born in Manhattan, the daughter of German immigrants Antonio Knauth, a lawyer, and Else M. (Uhlich) Knauth. German was spoken exclusively at home and she never completely lost her accent. As a girl, Langer learned to play both the cello and piano and for her early education attended Veltin private school. She studied at Radcliffe College, receiving her bachelors degree in 1920, and her doctorate in 1926. Alfred North Whitehead was her dissertation adviser. She taught at Radcliffe, Wellesley College, Smith College, and Columbia University and was visiting lecturer at a number of other institutions. In 1941 she met Ernst Cassirer whose work The Philosophy of Symbolic Forms she had read in the 1920s and had greatly influenced her thinking. Recognizing their common ground, Cassirer remained in close contact with Langer until his death in 1945.
In 1921 she married William L. Langer who later became a history professor at Harvard. They had two sons, Leonard born in 1922 and Bertrand born in 1925. In the late 1930s they drifted apart and were divorced in 1942.
From 1952 to 1962, Langer was professor of philosophy at Connecticut College. She was elected to the American Academy of Arts and Sciences in 1960. In 1956 she was awarded a grant from the Edgar J. Kaufmann Foundation which allowed her to devote the remaining 25 years of her life to research and writing.
Langer died in Old Lyme, Connecticut on July 17, 1985 after finishing the third volume of her magnum opus, Mind: An Essay on Human Feeling.