John McCarthy

John McCarthy (4 September 1927 – 24 October 2011) was an American computer scientist and mathematician who coined the term "artificial intelligence" in the 1955 proposal for the Dartmouth workshop, created the Lisp programming language, and developed logic-based approaches to common-sense reasoning.

McCarthy is associated with three durable contributions: the naming and institutional launch of AI as a field, the Lisp language that became a standard medium of symbolic AI research, and the programme of representing knowledge and reasoning in formal logic. He spent most of his career at Stanford, where he founded an AI laboratory. The Dartmouth event itself is covered in [HIST-002]; this entry concentrates on his own work.

McCarthy was born in Boston. He received a B.S. in mathematics from Caltech in 1948 and a PhD in mathematics from Princeton in 1951 with a dissertation titled "Projection Operators and Partial Differential Equations"; the formal doctoral adviser is reported inconsistently across sources and is not stated here (Wikipedia contributors, 2026b). He was an assistant professor at Dartmouth College from 1955, a research fellow at MIT in autumn 1956, and from 1962 a professor at Stanford, where he remained until retiring in 2000 (Wikipedia contributors, 2026b).

In 1955 he co-authored, with Marvin Minsky, Nathaniel Rochester and Claude Shannon, the proposal for the 1956 Dartmouth Summer Research Project, which introduced the phrase "artificial intelligence" (Wikipedia contributors, 2026b; Kline, 2011). Lisp was developed in the late 1950s and described in "Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I" (McCarthy, 1960). He died at Stanford, California, on 24 October 2011, aged 84 (Wikipedia contributors, 2026b).

Lisp. McCarthy (1960) presented a formalism for computing with symbolic expressions built from atoms and ordered pairs, using recursive functions, conditional expressions and a universal function that can interpret expressions as programs. The article defines the language's core in terms of a small set of primitive operations. Lisp's treatment of programs as data made it well suited to symbolic manipulation, which is why it was widely used in AI research.

Logic-based AI. McCarthy's paper "Programs with Common Sense" was presented at the Teddington Conference on the Mechanization of Thought Processes in December 1958 and is described on his archive page as probably the first paper on logical AI, in which logic is the method of representing information in computer memory (McCarthy, n.d.a). With Patrick Hayes he co-authored "Some Philosophical Problems from the Standpoint of Artificial Intelligence" (Machine Intelligence 4, 1969, pp. 463-502), described on his archive page as the basic paper on situation calculus (McCarthy & Hayes, 1969; McCarthy, n.d.b).

Circumscription. McCarthy (1980) proposed circumscription as a form of non-monotonic reasoning, a formal method for drawing conclusions that may be withdrawn when new information arrives, motivated by the need to represent default assumptions in common-sense reasoning.

McCarthy belonged to the symbolic or logicist tradition of AI, which holds that intelligent behaviour can be obtained by manipulating explicit representations with formal inference. Within the Dartmouth organizers, he and Marvin Minsky are credited with starting what became MIT's AI work (Wikipedia contributors, 2026c); the programmes of the Stanford and MIT groups differed in emphasis, a distinction often discussed in histories of the field. For knowledge representation as a topic see [FOUND-003].

Honours reported in secondary sources include the ACM A.M. Turing Award (1971), the Kyoto Prize (1988) and the US National Medal of Science (Wikipedia contributors, 2026b). The Kyoto Prize (Advanced Technology category, 1988) and the 1971 Turing Award were also confirmed to exist via the Kyoto Foundation and ACM recipient listings reached by search; the ACM citation wording was not retrieved and is not quoted. The US National Medal of Science is reported by the secondary source; its year was not confirmed and is not stated here. Lisp and its dialects remain in use, and the term he introduced is now the name of an industry.

Logic-based approaches faced practical difficulties with uncertainty, learning from data and the scale of common-sense knowledge, and statistical and neural methods displaced them in many applications (see [HIST-004] and [HIST-008]). McCarthy's own rationale for the term "artificial intelligence" and his emphasis on human-level generality are discussed in the historical literature; Kline (2011) examines how the Dartmouth narrative has been mythologized. Whether his logic programme can be reconciled with learned systems is an open research question (Contested).

The historical facts of authorship of the Dartmouth proposal and of the Lisp paper are documented in primary publications (McCarthy, 1960; Kline, 2011). The assessment of how much logic-based AI contributes to current practice varies by researcher.

No forecasts are made in this biography.

• Foundational Concepts:
  • HIST-002 The Dartmouth Workshop (1956): The event McCarthy proposed.
  • FOUND-003 Knowledge Representation: The subject of his logicist programme.
• Related Methods & Technologies:
  • HIST-003 Early Symbolic AI & The Perceptron: Symbolic AI in the following decade.
  • HIST-004 The AI Winters: Period in which symbolic approaches were criticised.
• Advanced Implications & Future Trajectories:
  • BIO-MINSKY-001 Marvin Minsky: Co-organizer of Dartmouth.
  • BIO-SHANNON-001 Claude Shannon: Co-organizer of Dartmouth.