1. Think about how you would play a public-goods game. Would it matter if you knew the other people with whom you were playing? Suppose you were playing with three other individuals under conditions of complete anonymity. Would it matter if you were playing these three individuals once, several times, or for an unknown number of repetitions?

2. It was well known before Fehr and Gächter did their experiments that when experimental subjects play prisoner's dilemma-like games such as public-goods games, there is a good deal of cooperation initially, but cooperation falls off as experimental subjects play more. What explanations can one offer for these data?

3. Under what conditions should the punishment option affect the behavior of rational experimental subjects who seek to maximize their earnings?

4. Are Fehr and Gächter's experimental results explained by facts about people's motives or by facts about the rules governing their interactions?

5. What is Fehr and Gächter's explanation for the experimental results that they find? How plausible do you think it is.

6. Adam Smith famously maintained, "He generally, indeed, neither intends to promote the public interest, nor knows how much he is promoting it. . . . he intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention." (Wealth of Nations, Book VI, Chapter 2) Smith is making claims both about individual motivation and about its consequences. How do the Fehr and Gächter experimental results bear on these claims?