Carl Hewitt is Emeritus in the Electrical Engineering and Computer Science department at the Massachusetts Institute of Technology (MIT). He obtained his PhD in mathematics at MIT in 1971, under the supervision of Seymour Papert (adviser), Marvin Minsky, and Mike Paterson. From September 1989 to August 1990, Hewitt was the IBM Chair Visiting Professor in the Department of Computer Science at Keio University in Japan. He is known for his design of Planner (a pioneering Artificial Intelligence programming language), his work on concurrency (the Actor model), the Scientific Community Metaphor with Bill Kornfeld, and, most recently, on strongly paraconsistent logic (Direct Logic). Hewitt's Erdős number is 3 (by two different co-authors).