John McCarthy

John McCarthy (1927–2011) was an American computer scientist and cognitive scientist who coined the term "artificial intelligence" and invented the Lisp programming language — one of the most influential languages in the history of computing. His 1958 proposal for Lisp introduced homoiconicity, the property that code and data share the same representation, enabling programs to manipulate their own structure.

McCarthy's 1955 Dartmouth Conference proposal defined AI as a research program: "every aspect of learning or any other feature of intelligence can in principle be so precisely described that a machine can be made to simulate it." This claim — that intelligence is formally describable and therefore mechanically reproducible — remains the foundational assumption of the field, and its most contested one.

Beyond Lisp and AI, McCarthy contributed to time-sharing systems (the CTSS project), garbage collection, and the formal semantics of programming languages. His work on situation calculus provided a logical framework for reasoning about action and change in AI planning systems.

McCarthy's genius was to recognize that the representation of knowledge matters more than the algorithm that processes it — an insight that the deep learning revolution, with its sub-symbolic distributed representations, has both validated and betrayed.