I. Topic: Competition, Selfish Behavior, "Tragedy of the Commons" Behavior

II. Purpose: To introduce students the the "tragedy of the commons," or degradation of a natural resource due to selfish behavior in a competitive situation.

III. Description: Demonstration (Materials needed: a large bowl, 20-30 paper clips, pennies, or computer diskettes (or 10 of any other class of similarly sized objects), a watch, and a medium size table or desk.)

This demonstration is based in part on Garrett Hardin's now class paper, "The tragedy of the commons" published in Science in 1968 (Volume 162, pp. 1243-1248) and on Edney's 1979 "Nuts Game, which is an analog to the dilemma Garrett described (see J. J. Edney, The nuts game: A concise commons dilemma analog in Environmental Psychology and Nonverbal Behavior, Volume 3, pp. 252-254.)

Basically, the tragedy of the commons occurs when people have equal access to shared resources (such as land). Each member of the group then acts to maximize his or her "investment" using that resource, which results in the degradation of the resource. The cause: each person acts in his or her self-interest, overlooking the fact that overuse of a resource will in the end may destroy it.

IV. Procedure:

1. Ask 4 volunteers to come to the front of the class. Have them stand around a medium size table so that they are facing the other class members.

2. On the table place a large bowl. In the bowl place 10 of anything--paper clips, pennies, computer diskettes, or any other similarly sized class of objects.

3. Explain aloud to the volunteers, so the other members of the class can hear, that the game they are about to play has only 2 rules.

Rule #1: The number of objects (whatever they may be) left in the bowl at the end of every 10 seconds will double.

Rule #2: The object of the game is to acquire as many objects in the bowl as possible.

4. Ask the volunteers if they understand the rule (they almost always do). Tell them the game will begin when you say go.

5. Say "GO!"

6. Monitor your watch carefully. When 10 seconds are up, stop the game and double the number of objects that are still in the bowl. If objects remain in the bowl, continue to play the game for several more rounds and pay careful attention to the strategy used by the volunteers to play the game. (You may ask students to explain their strategy, which may turn out to be a potential way to prevent the tragedy of the commons from occurring.)

However, chances are that there will be no objects left in the bowl. That is, as soon as you said, "GO," each volunteer dove his or her hands into the bowl attempting to get as many objects as possible before the other volunteers did (i.e., competitive behavior), causing the game to end prematurely. The volunteers are quick to remember Rule #2 but forget almost completely about Rule #1.

In this game, the objects represent some renewable resource, such as land or trees. The key to being renewable, of course, is that there must be something to renew. But because the students acquired all of the objects in the bowl, there was nothing left to renew, which models Hardin's point very nicely.