What Is Game Theory?

Game Theory is the science applied to the actions of people and firms facing uncertainty, viewing private economic decisions as moves in a game where participants devise strategies aimed at achieving objectives like gaining market share and increasing revenue.

Game Theory is a mathematical and economic discipline that examines how participants make decisions when confronted with competitive situations where the outcomes depend not just on their own actions but also on the actions of other participants. This field of study is crucial in understanding behaviors in an environment where uncertainty and interdependence are prominent aspects.

Key Concepts of Game Theory

Players

In Game Theory, “players” refer to the decision-makers involved in the game. These could be individuals, groups, firms, or any entities capable of strategic decision-making.

Strategies

A strategy is a complete plan of action a player will follow, given the set of circumstances that might arise within the game. Strategies can be pure or mixed:

• Pure Strategy: Each player makes a specific choice or following a particular course of action.
• Mixed Strategy: Players randomize over possible moves, potentially using probability distributions to choose between different strategies.

Payoffs

Payoffs are the rewards or outcomes that players receive from a set of strategies. These can be in the form of profits, utility, or other measurable gains or losses.

Information Sets

Information sets represent the knowledge available to players at each point in the game. Games can be classified based on the information available:

• Perfect Information: All players know the plays that have occurred before making their decisions.
• Imperfect Information: Some or all players do not have complete knowledge of the previous actions.

Equilibrium

An equilibrium is a state where no player can benefit by changing their strategy while the other players keep theirs unchanged. The most well-known is the Nash Equilibrium, named after John Nash.

$$ \text{Nash Equilibrium:} \forall i \in \{1, 2, \ldots, n\}, \quad s_i^* \in S_i \quad \text{such that} \quad u_i(s_i^*, s_{-i}^*) \geq u_i(s_i, s_{-i}^*) \quad \forall s_i \in S_i $$

Types of Games

Cooperative vs Non-Cooperative Games

• Cooperative Games: Players can form binding commitments or coalitions and negotiate collective strategies.
• Non-Cooperative Games: Players make decisions independently without forming alliances. This category includes much of classical game theory.

Zero-Sum vs Non-Zero-Sum Games

• Zero-Sum Games: One player’s gain is exactly another player’s loss. These games represent purely competitive situations.
• Non-Zero-Sum Games: The total payoff to all players can vary, and participants might have opportunities for mutually beneficial cooperation.

Simultaneous vs Sequential Games

• Simultaneous Games: Players make their moves without knowledge of the others’ actions.
• Sequential Games: Players make their moves in turns, and later players can observe preceding actions before deciding.

Applications of Game Theory

Game Theory is applied in several fields including economics, evolutionary biology, political science, and computer science. Key applications include:

Economics and Business

Game Theory helps in understanding market structure, auction design, bargaining, and forming competitive strategies. Firms can analyze how changes in pricing, advertising, production, and other factors affect their positioning and negotiation dynamics.

Political Science

It aids in voting systems, international relations, and the strategic decision-making of different political entities.

Evolutionary Biology

Game Theory models behaviors and strategies that influence the fitness and survival of organisms. Concepts like the Evolutionarily Stable Strategy (ESS) have been developed from this application.

Examples in Game Theory

Prisoner’s Dilemma

One of the most famous examples is the Prisoner’s Dilemma, a scenario where two individuals might not cooperate even if it’s in their best interest due to distrust and inability to negotiate.

Cournot Competition

A classic model in economics where firms choose quantities to maximize profit given the quantity chosen by competitors.

Frequently Asked Questions

What is Nash Equilibrium?

Nash Equilibrium is a solution concept where no player can do better by unilaterally changing their strategy, assuming all other players’ strategies remain unchanged.

How is Game Theory related to decision making?

Game Theory provides frameworks for strategic decision-making where outcomes depend on interdependencies of multiple decision-makers, helping in predicting and improving these decisions.

Why is Game Theory important in economics?

Game Theory offers insights into market dynamics and firm behaviors, helping to devise effective strategies and understand competitive environments.

References

1. Nash, John. “Non-Cooperative Games.” Annals of Mathematics, 1951.
2. von Neumann, John, and Oskar Morgenstern. Theory of Games and Economic Behavior. 1944.
3. Osborne, Martin J., and Ariel Rubinstein. A Course in Game Theory. MIT Press, 1994.

Summary

Game Theory is a foundational tool in understanding strategic interactions in various fields, particularly under conditions of uncertainty and interdependence. With its diverse applications, it continues to offer profound insights into competitive and cooperative behaviors across numerous disciplines.