What Is the Blue Part of Game Theory?


Diego Sanchez

Game Theory is a widely studied and applied concept in economics, political science, psychology, and other fields. It is a mathematical approach to understanding strategic decision-making where the outcomes of one’s choices depend on the decisions made by others.

In Game Theory, there are different strategies players can adopt in order to maximize their payoffs. One such strategy is known as the Blue Part.

What is the Blue Part?

The Blue Part refers to a player’s plan of action in a game that involves incomplete information. In such games, players do not have access to all relevant information about others’ preferences or strategies. As a result, they must make decisions based on their own beliefs about what others will do.

The Blue Part strategy involves choosing an action that mimics the behavior of rational opponents who are playing an optimal strategy. This means that even if players do not have complete information about their opponents’ preferences or strategies, they can still make reasonable assumptions based on what they do know.

In other words, players using the Blue Part strategy assume that their opponents are rational and will choose the best possible outcome for themselves given their own set of information. By mimicking this behavior, players using the Blue Part strategy can ensure that they are not exploited by opponents who may be making suboptimal decisions.

An Example

Consider a situation where two companies are deciding whether to invest in a new project. Each company has two options: invest or not invest. The payoff matrix for this game is shown below:

  • If both companies invest, they each earn $10 million.
  • If neither company invests, they each earn $1 million.
  • If one company invests but the other does not, the investing company earns $15 million while the non-investing company earns nothing.

Assume that Company A believes that Company B is rational and will choose to invest if the expected payoff is higher than not investing. In this case, Company A would use the Blue Part strategy and also choose to invest. This is because if Company B were to invest, the payoff for Company A would be $10 million instead of $1 million if they chose not to invest.


The Blue Part strategy is a useful tool in Game Theory when there is incomplete information about opponents’ preferences or strategies. By assuming that opponents are rational and will make optimal decisions given their own set of information, players can make reasonable assumptions about what their opponents will do and make strategic decisions accordingly. The use of such a strategy may help players avoid being exploited by suboptimal decisions made by opponents who may have incomplete information themselves.