Zero-Sum vs Positive-Sum Games
John von Neumann / Oskar Morgenstern · 1944
"Von Neumann distinguished zero-sum games — where one player's gain is exactly another's loss — from positive-sum games where mutually beneficial moves exist, arguing that misclassifying a positive-sum situation as zero-sum is one of the costliest strategic errors."
In 1944 von Neumann and Morgenstern formalized games where the chips on the table never change: poker hands, fixed-budget negotiations, and wars for territory are zero-sum; trade, innovation, and trust-building are not.
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Repeated Games & Axelrod's Tournaments
"Axelrod invited game theorists to submit programs for iterated prisoner's dilemma and the simplest — Tit for Tat, cooperate first then copy the opponent — won, showing cooperation can evolve without central authority when the shadow of the future is long enough."