Date: 2009-06-17 08:01:00
the tragedy of the commons

Most people have heard the familiar phrase "the tragedy of the commons", referring to the destruction of a common resource (eg. a grazing pasture) by multiple independent, rational actors each acting in their own self-interest (eg. cattle herders). The general idea is that each cattle herder will see all the benefits of adding one more cow to his herd, but the resulting drawback (depletion of the grazing pasture) is a cost shared by all.

Although I was familiar with the phrase and the idea, I had never read the original essay that it came from. In 1968 Science magazine published Garrett Hardin's essay titled The Tragedy of the Commons, which in a rare example of electronic availability of pre-Internet content, is available online in its full form.

What I did not realise is that the article is not actually about cows. The article is about people, specifically humans, and the commons is the world in which we live. The article is about the population explosion. In 1968, the population of the world was somewhere between 3.3 and 3.7 billion. Today it is estimated to be 6.7 billion, nearly double the number of people from the time the article was written. From the conclusion of the essay:

The most important aspect of necessity that we must now recognize, is the necessity of abandoning the commons in breeding. No technical solution can rescue us from the misery of overpopulation. Freedom to breed will bring ruin to all.

The essay suggests that the freedom to breed must be curtailed if we, as the occupiers of this finite planet, are to survive and prosper. "[I]t is the role of education to reveal to all the necessity of abandoning the freedom to breed." If you have not yet read this essay from start to finish, go do so now. It's not a quick read, but it's not something we can ignore.

I haven't read this yet, but I've thought about it before. Yes, we are doomed to a future of overpopulation if we don't control our numbers, but how do you enforce such a thing? Education helps, yes, but there will always be those that believe that it is their duty to "go forth and multiply". Then what? Does the state start doing forced sterilizations? That sort of thing sounds repugnant to me.

In the end, population problems will solve themselves. With overpopulation also comes greater chance of famine and disease. If the population grows larger than the earth can support... well... it'll shrink. It's not a very cheery prognosis, and certainly not how I'd like things to play out, but at least I'll be dead by then. :p
The essay doesn't address what kind of restrictions on reproduction might be feasible. It stops at making the case that something is necessary, but not what. I don't have any good ideas on implementing controls either, but see China for their prototype implementation.

Population problems will eventually solve themselves, but before that happens it will get a lot worse. How long will it take the earth to recover after overpopulation takes its toll? I'm guessing tens of thousands of years.
The population control in China is pretty much a way for officials to get kick backs. Sure, poor people can't have more than 1 child but even slightly above poor people can afford to have multiple children with the proper bribes. Elaine has 2 sisters for example.
It's taking care of itself, but it will be a bumpy ride.

The problem is in the third-world/developing/whatever-the-term-is-this-week nations.

In the industrialized countries (with one exception), the population is actually shrinking. The exception is the US, and that's only because immigration is making up the difference between the birth and death rates.

This is causing some concern in Europe and Japan. As the population ages and retires, there won't be enough young people to step up and replace them.

India and China are trying to slow things down. Ironically, I don't think government policies are what's going to help them, but rather the preference for sons combined with the practice of aborting girl fetuses. This has already skewed the sex ratios of their populations.

Africa seems to be doing its best to take care of its surplus population without anyone's help. A few more famines and genocides...
A slight tangent: Hardin's interpretation of Bentham's "the greatest good for the greatest number" is quite different from how I always understood that utilitarian sentiment. He interprets it as "maximize the number of people and maximize their good", i.e. as a call to increase the population as much as possible and to improve the quality of living for those people. I have always understood it to merely be a call to improve the quality of living for as many people (who already exist) as possible, without the additional notion of also maximizing the number of people who exist.

Based on a tiny bit of web research now, I have the impression that my understanding of Bentham's idea is correct (i.e. it's not also a call to increase the population size as much as possible), but I'm not sure, and it's funny that such a famous phrase as "the greatest good for the greatest number" has such an apparently ambiguous meaning!
I agree with your understanding too, I wouldn't assume that the intention was to maximize both variables at the same time. Of course, maximizing two variables in a nonlinear system presents its own difficulties.

I don't think that Hardin's possible misinterpretation of that statement harms his overall argument though.
Agreed, and I didn't mean to suggest that Hardin's main point was bogus. I agree that exponential growth is not sustainable.

There is an interesting argument I heard decades ago: some people claim technology can solve the problem since if we get space travel and colonization, then population growth would no longer be a problem, since we can just keep expanding outward to new planets. But thinking about an expanding sphere of outward colonization from Earth, our lebensraum would be growing at a cubic growth rate, which is still dominated and eventually overtaken by exponential population growth.
I've also heard that cubic vs exponential observation before, but I can't recall where. It may have been in some book I read years ago that may have had something to do with the Drake equation.

A guy I was talking to yesterday made the argument that human populations tend to stop growing when the life expectancy reaches a certain threshold. While there is evidence of a correlation, I'm not convinced that there's more than a correlation. I guess time will tell.
Greg Hewgill <>