> You might have acted rationally had you decided to take the exam, but you'll find that social pressure will occasionally make everyone (a) much nicer than you, and (b) in blatant disregard of game-theoretic rationality.

I definitely would have acted rationally, because I place very little value on getting to skip an exam or on proving a point about the grading system, and much more value on actually getting the education I paid for.

> Actually, to make it a real case of Prisoner's Dilemma, he could have given the students who took the test a 100 and everyone else a 0, but given everyone an 80 if no one took the test. Which I would have found much more interesting.

It's already a real case of the prisoner's dilemma, but with different rewards for different people depending on what they value. Most of the students in the article placed a higher value on not having to take the exam. I would place a higher value on taking the exam.