L. (Lizzie) Susan Stebbing was one of six siblings brought up by a guardian after the early death of their parents. Her early education was interrupted periodically by ill-health. She read history at Cambridge University, where she became so interested in philosophy (moral sciences) that she decided to pursue further study of it. She earned a master's degree at King's College London and later a D. Litt at Bedford College. In 1915, she became part-owner of a school for girls in Hampstead with her sister and two friends.
She taught there and also held positions at King's College and Bedford College, London, where she was named professor of philosophy in 1933. Her first book, A Modern Introduction to Logic, was published in 1930. With poet C. Day-Lewis, she wrote Imagination and Thinking (1936). Her other books included the popular and influential Thinking to Some Purpose (1939). She was active in the Aristotelian Society with Bertrand Russell, Alfred North Whitehead, and G.E. Moore, and was a founder of the journal Analysis. She died in 1943 at age 57.