Born in Victoria B.C. in 1944, Duncan now lives in Vancouver. Following graduation from the University of Alberta he joined the Department of Finance (Ottawa) in 1966 and was financial advisor to the Canadian Delegation at the United Nations General Assembly in 1967. After working at the Canadian International Development Agency (CIDA), he went on to complete a doctorate from the University of Paris I (Paris-Sorbonne) in 1976.
Duncan is an adjunct professor of political science at Simon Fraser University, a director of the Karl Polanyi Institute of Political Economy at Concordia University in Montreal, and a research fellow of the Centre for Global Political Economy at SFU. He was a member of the political science department at the University of Ottawa from 1975 until 2004.
He is the author, co-author, editor or coeditor of 11 books including Ethics and Economics (with Gregory Baum), The Other Macdonald Report (with Daniel Drache), The Free Trade Papers, The Free Trade Deal, Canada Under Free Trade (with Mel Watkins) and Constitutional Politics (with Miriam Smith).