Behavioural economics emerged from the insight that human beings are not the purely rational agents that classical economics assumed. Drawing on decades of research in cognitive psychology, behavioural economists demonstrated that people systematically deviate from rational choice in predictable ways: they overweight immediate rewards relative to future ones (present bias), they are more sensitive to losses than to equivalent gains (loss aversion), they anchor their judgments to irrelevant initial numbers, and they are powerfully influenced by the way choices are presented (the framing effect).
Richard Thaler and Cass Sunstein applied these insights to policy in their concept of the ‘nudge’ — designing choice environments so that people’s predictable cognitive tendencies are channelled toward better outcomes, without restricting their freedom to choose otherwise. The classic nudge is the default: if organ donation is the default option on a driving licence form, far more people will be organ donors than if they must actively opt in. The choice is free, but the architecture of its presentation does most of the work.
Critics of nudge theory argue that it is paternalistic — that it treats people as irrational subjects to be managed rather than autonomous agents to be respected. Defenders respond that the choice environment is always designed by someone, and that designing it to serve the majority’s own stated preferences — rather than those of commercial interests or default inertia — is not manipulation but a form of respect.