Liberal Forum

Developed by Daniel Kahneman and Amos Tversky in 1979, prospect theory is a behavioral model describing how people make decisions under uncertainty. It reveals that individuals evaluate potential gains and losses relative to a specific reference point rather than their final wealth, and generally fear losses far more than they desire equivalent gains.Core Principles of Prospect TheoryThe theory outlines two primary phases in the decision-making process: the Editing Phase and the Evaluation Phase.1. The Editing PhaseIn this initial step, individuals simplify and frame the available outcomes. They use mental shortcuts to set a baseline (reference point) and decide which information is important before choosing. This makes people highly susceptible to framing effects, where the exact same decision yields vastly different choices depending on whether it is presented as a "gain" or a "loss".2. The Evaluation PhaseDuring this phase, individuals assess options based on two key functions:The Value Function: This demonstrates three things about human psychology:Reference Dependence: Outcomes are viewed as deviations from a neutral reference point rather than absolute numbers.Loss Aversion: The pain of losing $100 is psychologically much stronger than the joy of gaining $100.Diminishing Sensitivity: The psychological impact of marginal gains or losses decreases as the amounts grow larger.The Probability Weighting Function: People do not evaluate probabilities objectively. Individuals tend to overweight small probabilities (leading to a fascination with lotteries and the tendency to over-insure against rare events) and underweight moderate-to-large probabilities.Why It MattersHistorically, traditional economics relied on the Expected Utility Theory, which assumes humans always act with perfect rationality to maximize their wealth. Prospect Theory revolutionized economics and psychology by explaining why humans consistently make seemingly irrational, paradoxical choices. It forms the bedrock of behavioral economics and has profound applications in finance (e.g., the disposition effect), politics, and marketing.