American economist known for his contributions to welfare economics and to general economic equilibrium theory. He was cowinner (with Sir John R. Hicks (Hicks, Sir John R.)) of the Nobel Prize for Economics in 1972. Perhaps his most startling thesis (built on elementary mathematics) was the “impossibility theorem” (or “Arrow's theorem”), which holds that, under certain conditions of rationality and equality, it is impossible to guarantee that a ranking of societal preferences will correspond to rankings of individual preferences when more than two individuals and alternative choices are involved.

In one of his earliest articles, published in 1951, Arrow showed that a competitive economy in equilibrium is efficient. Furthermore, he demonstrated that an efficient allocation could be reached if a government uses lump-sum taxes to transfer wealth and then lets the market work toward equilibrium. One implication of his findings is that, if a government chooses to redistribute income, it should do so directly rather than through price regulations that could hamper the free market. Arrow's early work on equilibrium still stands as one of the reasons many economists oppose price controls.

After receiving his Ph.D. from Columbia University in 1951, Arrow taught at the University of Chicago (1948–49), at Stanford University (1949–68), and at Harvard University (1968–79). In 1979 he returned to Stanford University.

Among Arrow's major publications are Social Choice and Individual Values (1951), Essays in the Theory of Risk Bearing (1971), and The Limits of Organization (1974).