Friday, May 21, 2004

Tragedy of the Commons: Again

Yesterday we talked about the tragedy of the commons. Here is another example to illustrate it.

Suppose there are two buildings, A and B, and a sidewalk between them. Most people walk on the sidewalk to get from A to B. Unfortunately, the sidewalk does not follow a straight line between A and B and, as we know, a straight line is the shortest distance between two points.

The shortest distance between A and B is across the grass lawn between the two buildings. One day, you want to get from A to B as quickly as possible. You decide to walk across the grass. Now your walking across the grass doesn't really harm the grass. You are only one person. In other words, the thought here is: My action does not change things much at all, so it is okay to walk across the grass. It doesn't follow that because I walked across the grass that the lawn is going to be broken up in any way.

What we have here, in general, is the sense that your single action does not change things adversely.

But, of course, what holds for you holds for others too. Suppose other people are in a hurry and decide to cut across the lawn. Each of these persons says the same thing you said: My single action does not mean much here.

When a lot of people, each only contributing a tiny tiny bit of harm, do the same thing, we can often get a change in the world. Over time, we get a dirt path across the grass lawn.

Once the dirt path is there, each person may look at it and wish it weren't there. But, of course, it was each person who contributed to the dirt path. A lot of little actions (each one by itself insignificant) ended up producing something (a dirt path) that was very significant (a big change from what once was).

The grass lawn is the commons -- it is the resource owned in common by everyone.

The tragedy is the fact that the commons changes in a way people don't really want it to change.

Also, the tragedy is that no individual had any incentive not to walk on the grass because each individual saw his action as meaning very little to the total.

Now Hardin, the author of the tragedy of the commons, said that the tragedy will be no more if --and only if -- we convert the grass from common property to private property. Once someone owns the grass, he can put up signs that say do not walk on the grass, we can fine people if they do walk on the grass, and so on.

In other words, private property is the way out of the tragedy of the commons.


At 12:01 AM, Blogger Eric said...

Very interesting post. I agree with the general principle. The underlying principle that each of us believes our own, little actions have no great consequence has lead people to do things that they later regret. However, I am not certain that the answer is to make all these "areas" private property. All that stops is people who value private property, or who fear fines from violating the common areas. The rest will decide to ignore the prohibition, often using the very same justifications that they used before.


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