John Harsanyi, John Nash, and Reinhard Selten
Citation: For their pioneering analysis of equilibria in the theory of non-cooperative games.
The key idea
Nash equilibrium: in strategic interactions, each player chooses a best response to the others. Harsanyi extended this to incomplete information. Selten refined to subgame-perfect equilibrium.
The explanation
Nash (1950) defined the equilibrium concept that bears his name and proved it exists for finite games. Harsanyi (1967) extended Nash equilibrium to games with incomplete information by introducing 'types' of players drawn from a common prior. Selten refined the concept to rule out non-credible threats.
Why Africa should care
Game theory is the right framework for African cartel analysis: cement (Kenya, Tanzania, Nigeria), banking (the Big Four in Kenya), sugar refining, and telecom. Repeated-game logic explains why these oligopolies remain stable despite competition policy. Tax compliance and corruption equilibria are also Nash equilibria — multiple stable points (high-trust low-corruption vs low-trust high-corruption), with transitions difficult.
How to use it
When analysing an industry with few players, draw the payoff matrix. Identify the Nash equilibrium. If it's collusive but Pareto-dominated by competition, ask what would change beliefs and break the coordination.
Canonical works
- John F. Nash (1950) "Equilibrium Points in n-Person Games" Proceedings of the National Academy of Sciences
- John C. Harsanyi (1967-68) "Games with Incomplete Information Played by 'Bayesian' Players" Management Science
- Reinhard Selten (1975) "Reexamination of the Perfectness Concept for Equilibrium Points in Extensive Games" International Journal of Game Theory
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