Daniel Kahneman (1934-2024) won the Nobel Prize in Economics in 2002 for his research (with Amos Tversky) demonstrating systematic departures from rationality in human judgment and decision-making. Their heuristics and biases research program, launched in the early 1970s, showed that people rely on cognitive shortcuts (heuristics) that are usually effective but can lead to systematic, predictable errors (biases). This work transformed economics, medicine, law, public policy, and everyday understanding of the human mind.
Heuristics and Biases
Kahneman and Tversky identified three major heuristics. The availability heuristic: judging probability by the ease with which examples come to mind (overestimating dramatic risks like plane crashes). The representativeness heuristic: judging probability by similarity to a prototype (base rate neglect, the conjunction fallacy). Anchoring and adjustment: estimates biased toward an initial value. These heuristics are not irrational but are adaptive strategies for making judgments under uncertainty — they work well in most situations but produce systematic errors in specific, identifiable circumstances.
Kahneman's 2011 bestseller Thinking, Fast and Slow presented his dual-process framework to a general audience: System 1 (fast, automatic, intuitive, effortless) and System 2 (slow, deliberate, analytical, effortful). System 1 generates impressions, intuitions, and heuristic judgments; System 2 monitors and sometimes overrides System 1, but is lazy and often endorses System 1's suggestions without careful scrutiny. This framework provides an accessible and scientifically grounded account of why humans are simultaneously brilliant and predictably irrational — and has become one of the most influential frameworks in modern cognitive psychology.