28 February 2008

40th Anniversary for Tragedy of the Commons

I just recently realized that this year is the 40th anniversary of Garret Hardin's seminal essay "Tragedy of the Commons" (ToC).

Hardin, who died in 2003, argued that the Earth is commons, and that we're rapidly overpopulating it. (Oddly, Hardin did not cite Malthus.) The tragedy is that there is no technical solution to the problem, that is, no way to win without radically revising the game itself. Voluntary restraint in childbearing would lead to those voluntarists being outbred by those who didn't restrain themselves. The only solution, therefore, is "mutual coercion, mutually agreed upon," because "the freedom to breed is intolerable." Because of ToC's environmental implications, Hardin inarguably has had more influence in the social sciences than any other biologist.

Certainly population growth since the 1960s has been tremendous, as is shown in this chart. But the rate of growth has declined, so we will stabilize at some point in the future.

Source: United Nations.

But as can be seen in the second graph, population growth is almost wholly a function of underdevelopment. As people grow wealthier, they tend to shift along the r-k reproductive continuum from a more r-type strategy, to a more k-type strategy, resulting in fewer childen, and slower population growth.

Source: United Nations. Found at Population Reference Bureau.
The critical problem in Hardin's argument appears to be his assumption that having more children is always individually rational (or, from the biological perspective, always selectively advantageous). But philosopher Stephen Gardiner persuasively argues that this assumption is both theoretically erroneous, and not supported by empirical data.

One of the predicted outcomes of overpopulation was pressure on available resources. To that end, Paul Ehrlich, who famously predicted that much of the world would starve to death in the 1970s, accepted a bet with economist Julian Simon, concerning the future price certain resources (Simon let Ehrlich select them, and Ehrlich chose 5 metals). If they became scarcer due to population pressure, the price would increase. Ehrlich lost the bet, and just recently economist Mark Perry has argued that if the bet had been repeated between 1990 and 2000, Ehrlic still would have lost.

Most people, including me, are worried about overpopulation of the Earth, but empirical evidence that we've reached or exceeded carrying capacity is scarce. But I think the whole issue is compelling enough that I've begun planning a 40-year retrospective symposium at my college. It's much too early to say whether I'll pull it off, but I think it would be very interesting to get a variety of perspectives on Hardin's argument with the benefit of 40 years of thought and accumulated evidence.


James K said...

I'm not at all worried about overpopulation. I'll tell you why.

The Earth's carrying capacity is a function of technology. Thanks to nitrate fertilzer and the Green Revolution the world is less overpopulated than it has ever been.

If we can get the luddites at Friends of the Earth and Greenpeace to sit down and shut up, I see no reason why genetic modification can't keep us running until almost everyone is rich enough to push fertility down.

In fact I predict that in 50 years the real problem will be underpopulation.

James Hanley said...

James K, that's a dangerous statement in some locales!

I think there has to be some limit to population, but I have no idea what it would be because, as you point out, it's a function of technology. But I'm not sure I'd want to live in a world where everyone has to live in highrises just to fit us all in. Fortunately we're not near that yet.

But underpopulation is a real problem, as Europe has found out. And apparently Japan is beginning to worry that declining population is in their future--and unlike Europe they won't be as quick to invite in guest workers.

James K said...

I know its dangerous, that's why I enjoy saying it, sacred cows make the tastiest hamburger :)

Population must indeed be limited at some point, but who knows where. GIven how fundamentally technology will change humanity in the next century, all I'm willing to guess is that we have as much chance of predicting correctly as a medieval scholar would have at predicting how things are now.

James Hanley said...

"all I'm willing to guess is that we have as much chance of predicting correctly as a medieval scholar would have at predicting how things are now."

I agree that it's always good to have a little humility about predicting the future. I've never forgotten going to Disney's EPCOT (Experimental Prototypical Community of the Future--built in 1961) in 1981 and thinking how sadly dated it looked.

As I got older, I realized the concurrent ingenuity of thousands--tens of thousands--of minds would inevitably come up with far more ideas and solutions than a handful of purposeful planners could. And how much more so when the tens of thousands, each looking for one small innovation, are stacked up against a group of people who are mostly frozen in fear by the sight of the big problems. The latter's only real accomplishment is to draw the attention of those creative folks to the problems they see (if, in fact, they're really the first ones to see them, as they generally think they are).

James K said...

Very true.

By the way, I think the technical term for the EPCOT centre thing is Zeerust: The tendency of "futuristic" looks to appear dated in a short space of time.