Ernst Alfred Cassirer (July 28, 1874 – April 13, 1945) was a German philosopher.
Trained within the Neo-Kantian Marburg School, he initially followed his mentor Hermann Cohen in attempting to supply an idealistic philosophy of science.
After Cohen's death, Cassirer developed a theory of symbolism and used it to expand phenomenology of knowledge into a more general philosophy of culture.
Cassirer was one of the leading 20th-century advocates of philosophical idealism. His most famous work is the Philosophy of Symbolic Forms (1923–1929).