Neumann was an intellectual at the Institute for Social Research (known as the Frankfurt School).

He is known for his theoretical analyses of Nazism, and for his analysis of Nazi political economics.

• He worked for the Office of Strategic Services (OSS)–the precursor to the U.S. Central Intelligence Agency (CIA)–from 1943 to 1945.

• He also spied for the Soviet Union during World War II under the code-name “Ruff”.