Where does zero-sum collide?

In game theory a zero-sum (or constant-sum) game is one in which the players' payoffs always add to a fixed total, so whatever one player wins another must lose and there are no gains from cooperation. von Neumann's 1928 Zur Theorie der Gesellschaftsspiele proved the minimax theorem for exactly this case: every finite two-person zero-sum game has a well-defined value and optimal (possibly mixed) strategies that each player can guarantee. The referent is a precise structural property of a payoff matrix, not an attitude; it says the interests of the players are strictly opposed, and it is what makes such games uniquely solvable.[1]

Unit

The constant to which the players' payoffs sum in every outcome

Recovery means

Not applicable

Measured by

Established by checking that payoffs sum to a constant across outcomes, and solved via the minimax value and optimal mixed strategies

In psychology “zero-sum” names a belief rather than a game: the perception that one person's or group's gain must come at another's expense, applied even to situations where resources are not actually fixed. Różycka-Tran and colleagues' 2015 37-nation study treats belief in a zero-sum game as a measurable social axiom that varies across people and cultures, and Meegan's 2010 work documents a zero-sum bias in which people perceive competition despite unlimited resources. The referent here is a cognitive–attitudinal disposition measured by survey, which borrows the game-theoretic label but describes how people (often mistakenly) construe interdependence, not a formally zero-sum payoff structure.[2][3]

Unit

Strength of the belief that gains and losses are necessarily linked

Recovery means

Not applicable

Measured by

Assessed with self-report scales (e.g., the Belief in a Zero-Sum Game scale) and behavioral tasks revealing zero-sum bias