An economics and business concept defining a measure, method, or organizational practice used for analysis and decision-making. It specifies how information is generated or used to guide allocation of resources and evaluation of outcomes. It does not ensure correctness without clear assumptions, reliable inputs, and appropriate review of results. It materially affects planning, performance, and risk by shaping decisions and incentives within organizations and markets. The concept is generally stable, though methods and tools evolve over time.

Principle

Make choices by maximizing the probability-weighted average of utility across all possible states; preferences that obey independence and completeness admit representation by expected utility.

Demonstration

A gamble that pays $100 with probability 0.5 and $0 with probability 0.5 has expected utility 0.5·u(100)+0.5·u(0); comparing that value to the expected utility of alternative gambles selects the preferred option.

Misapplication

Treating expected utility as descriptive for all observed behavior (e.g., using it to rationalize choices that violate independence or exhibit probability weighting) or applying it when probabilities are unknown leads to misleading predictions.

Consequence

When applicable, the expected-utility rule yields determinate rankings of risky prospects, allows comparative statics on risk aversion via utility curvature, and delivers tractable optimization in portfolio choice and insurance.

Reversal

Maximizing expected monetary value rather than expected utility in contexts with nonlinear utility can reverse preferences: a higher expected dollar payoff may be rejected by a risk-averse agent.

Boundary

Applies when objective or subjective probabilities are available and preferences adhere to vNM axioms; it excludes ambiguity (unknown probabilities), violations like prospect-theory weighting, and contexts where outcomes are non-comparable utilities.

Semantic Tension

Competes with alternative descriptive models (prospect theory, rank-dependent utility) that alter probability weighting or reference dependence while sharing the goal of explaining choice under risk.

Synthesis

Expected utility condenses a decision under risk into a single probability-weighted utility number, enabling normative and predictive statements where vNM assumptions hold, but it must be distinguished from models that relax independence or probability-linear weighting.