Apel grew up during the political crises of the Weimar Republic. In 1940 he was a war volunteer with his entire graduating class. After the Second World War Apel studied from 1945 to 1950 at the Rheinische Friedrich-Wilhelms-University Bonn, first history and intellectual history, before he committed himself as a student of Erich Rothacker on philosophy.

Karl-Otto Apel (German: [ˈaːpl̩]; born March 15, 1922) is a German philosopher and Professor Emeritus at theUniversity of Frankfurt am Main. He developed a distinctive philosophical approach which he called "transcendental pragmatics" (Transzendentalpragmatik).^[1]