Nash Equilibrium
A strategic outcome is stable when no player can improve by changing strategy alone.
The Mechanism: A Nash equilibrium is a set of strategies where no participant can gain by changing their own strategy while others keep theirs fixed. It describes a form of strategic stability, not necessarily a fair or efficient result.
The Philosophical Pivot: Stability can reflect mutual dependence rather than agreement. People may remain in an outcome they dislike because each fears being the only one to move.
The Horizon: The concept helps analyze markets, bargaining, and social conventions. Some games have multiple equilibria, and equilibrium predictions depend on what players know and how they interpret the situation.
A stable outcome is not automatically optimal. The prisoner's dilemma shows how equilibrium behavior can leave everyone worse off than coordinated alternatives.
Institutions can help people move by changing payoffs, coordinating expectations, or making commitments credible.
Understanding equilibrium reveals why telling individuals to choose differently may fail when the surrounding incentives stay the same.
A pattern can be stable because everyone is trapped in responding to everyone else.
Which shared arrangement persists not because anyone endorses it, but because no one can change it alone?