On John McCarthy's 80th Birthday, in Honor of His Contributions

John McCarthy's contributions to computer science and artificial intelligence are legendary. He invented Lisp, made substantial contributions to early work in timesharing and the theory of computation, and was one of the founders of artificial intelligence and knowledge representation. This article, written in honor of McCarthy's 80th birthday, presents a brief biography, an overview of the major themes of his research, and a discussion of several of his major papers. It was not his dream of an intelligent computer that was unique, or even first: Alan Turing (Turing 1950) had envisioned a computer that could converse intelligently with humans back in 1950; by the mid 1950s, there were several researchers (including Herbert Simon, Allen Newell, Oliver Selfridge, and Marvin Minsky) working in what would be called artificial intelligence. What distinguished McCarthy's plan was his emphasis on using mathematical logic both as a language for representing the knowledge that an intelligent machine should have and as a means for reasoning with that knowledge.