Alfred William Benn was an agnostic and an honorary associate of the Rationalist Press Association. His book A History of Modern Philosophy was republished in the Thinker's Library series in 1930.
He was the author of The Greek Philosophers; The History of English Rationalism in the Nineteenth Century; and The History of Ancient and Modern Philosophy.
Benn was also a member of the London Positivist Society and a friend of the lawyer and positivist Vernon Lushington. Lushington's daughter Susan recorded in her diary on 3 September 1889 that Benn and his wife visited the Lushington's Surrey home - Pyports, Cobham - and how Mrs Benn told her "how she came to be a positivist."