TLDR: In Prisoner's Dilemma, defecting is a dominant strategy, and both players defecting is the only Nash equilibrium. In Snowdrift, there is no single dominan

TLDR: In Prisoner's Dilemma, defecting is a dominant strategy, and both players defecting is the only Nash equilibrium. In Snowdrift, there is no single dominant strategy, and no Nash Equilibrium exists at all. By design, the Snowdrift game rewards cooperation more than Prisoner's Dilemma, so it's no surprise that people cooperate more in Snowdrift. The real question is which game better models reality. http://www.gametheory.net/dictionary/DominantStrategy.html http://www.gametheory.net/dictionary/DominantStrategy.html https://en.wikipedia.org/wiki/Nash_equilibrium https://en.wikipedia.org/wiki/Nash_equilibrium