The Cobra Effect describes a class of interventions that worsen the problem they were designed to solve, due to perverse incentives or behavioral adaptations. Named after the apocryphal story of cobras bred for British-colonial bounties in India, it is a specific and important category of unintended consequences where the solution directly causes the problem to intensify.
The Prisoner's Dilemma is the foundational scenario in game theory illustrating how two rational actors can each have incentives to betray the other, even though mutual cooperation would produce better outcomes for both. Formulated by Merrill Flood and Melvin Dresher (1950) and named by Albert Tucker, it is the paradigm case for understanding why rational self-interest can produce collective irrationality, and why cooperation requires mechanisms beyond individual incentive.