The cause was brain cancer, said his wife, Anne Solomon. He retired in 2012 after 19 years leading the United States Institute of Peace, a congressionally funded research group for conflict resolution. He earned his Ph.D. in political science, with a specialization in Chinese politics, from the Massachusetts Institute of Technology.
Dr. Solomon was an intellectual polymath whose interests encompassed science, photography and international affairs. His career took him from academia to senior positions in government and think tanks. He received the American Political Science Association’s Hubert H. Humphrey career award for “notable public service by a political scientist” in 2005.