Hartman was born in Germany, in an AshkenaziJewish family. In 1939 he left Germany for England as an unaccompanied Kindertransport child refugee, sent away by his family to escape the Nazi regime. He came to the United States in 1946, where he was reunited with his mother, and later became an American citizen.
His work explores the distinction between literature and literary commentator. He helped found the Yale Video Archive for Holocaust Testimonies, and lectures on issues dealing with the production and implications of testimony.