 Puzzles with the structure of the prisoner's dilemma were discussed by Merrill Flood and Melvin Dresher in 1950, as part of the Rand Corporation's investigations into game theory (which Rand pursued because of possible applications to global nuclear strategy). The title “prisoner's dilemma” and the version with prison sentences as payoffs are due to Albert Tucker, who wanted to make Flood and Dresher's ideas more accessible to an audience of Stanford psychologists. More recently, it has been suggested (Peterson, p1) that Tucker may have been discussing the work of his famous graduate student John Nash, and Nash 1950 (p. 291) does indeed contain a game with the structure of the prisoner's dilemma as the second in a series of six examples illustrating his technical ideas. Although Flood and Dresher (and Nash) didn't themselves rush to publicize their ideas in external journal articles, the puzzle has since attracted widespread and increasing attention in a variety of disciplines. Donninger reports that “more than a thousand articles” about it were published in the sixties and seventies. A Google Scholar search for “prisoner's dilemma” in 2018 returns 49,600 results.