American economist, political scientist, cognitive psychologist, and computer scientist; Nobel laureate in economics (1978), Turing Award winner (1975), and one of the few 20th-century thinkers of any field who did first-rank work in four disciplines. The organizing idea of that work — that human beings are boundedly rational, with cognitive resources too limited to optimize but sufficient to satisfice — is the premise from which behavioral economics, decision theory, much of organization theory, and the first generation of artificial intelligence all developed.
Simon was born in Milwaukee, took his doctorate in political science at the University of Chicago in 1943 with a dissertation on administrative decision-making published as Administrative Behavior (1947), and spent his career from 1949 onward at Carnegie Mellon, where he was a founding figure of what became the Graduate School of Industrial Administration and, with Allen Newell, of the cognitive-science department. Administrative Behavior is the book in which bounded rationality and satisficing first appear as technical terms: real administrators, Simon argued against the then-dominant "principles of administration" school, do not optimize; they search until they find an alternative that is "good enough" by some acceptable standard, and they proceed. The 1978 Nobel was explicitly for the research program this opened.
From the mid-1950s Simon, with Newell and the programmer Cliff Shaw, was one of the founders of artificial intelligence. Their Logic Theorist (1956) was, by most counts, the first running AI program — it proved theorems from Whitehead and Russell's Principia Mathematica, including one with a more elegant proof than the original. The General Problem Solver (1959) followed. Simon and Newell's 1976 Turing Award lecture, "Computer Science as Empirical Inquiry: Symbols and Search," stated the physical symbol system hypothesis — that general intelligent action requires a system that can manipulate symbols in the way a computer does — which remained the dominant programmatic claim of "classical" AI until the connectionist and statistical-learning turns of the 1990s and 2010s.
Human Problem Solving (1972, with Newell) is the long statement of the symbol-processing account of cognition. The Sciences of the Artificial (1969, revised 1981, 1996) is the shorter book in which Simon set out the argument that human-made systems — organizations, economies, designed artifacts — are the proper subject of their own general science, distinct from the natural sciences of given matter. It remains in print and widely taught in design, management, and systems theory.
Simon's political-theoretical contribution is less widely known but substantial. He argued against the neoclassical-economic picture of the firm as a nexus of contracts for a picture in which the firm is an actual authority-based organization, and against Friedrich Hayek's picture of the market as the unique information-processing solution for a picture in which both markets and hierarchies are imperfect boundedly-rational arrangements. His position was broadly supportive of a regulated, mixed-economy social democracy; he was an early critic of the neoliberal turn of the 1980s. He died at Carnegie Mellon in 2001.
Simon belongs here because bounded rationality is the premise from which the graph's political-economy critics (of markets-as-optimal, of managerial rationality, of rational-choice political science) all implicitly work, and because his account of the firm as a hierarchical authority-based organization cuts across the libertarian / social-democratic debate the graph's political-economy cluster carries.