Word
Nash equilibrium
A set of choices in which no player can do better by changing course alone while everyone else stays put
Examples
During a nuclear standoff, neither state can safely disarm while the other stays armed.
Rival firms may keep prices low because either one that raises its price alone will lose customers.
Origin
Named for mathematician John Nash. In 1950, at age twenty-one, he proved that every finite game has at least one equilibrium when players may randomize among strategies. The idea became central to modern game theory.
How it connects
The word names the lock: a set of choices no one can improve alone.
This word appeared in Why bad outcomes endure, the Involves connection for August 13, 2026, which asked: Why can a dangerous situation persist when everyone wants something better?
Check yourself
When is a situation a Nash equilibrium?
No player can do better by changing course alone while everyone else stays put.. Right. Each choice is a best response to the others, so nobody moves alone, whether or not anybody is happy.
What the sources establish
Nash's 1950 note proved that every finite n-person game has at least one equilibrium point.
Sources
Equilibrium Points in N-Person Games (John F. Nash Jr., 1950), Pages 48–49