Thursday, May 22, 2008

Tragedy of the Commons

cow in fieldImagine you're a medieval villager. You have access to a common - a fertile pasture that is owned by all the villagers together. The common can support 100 sheep - any more and the pasture would turn into a muddy wasteland. So the 20 households in the village each graze 5 sheep on the common, including yours.

One day you have a brilliant idea. If you got another sheep, that would only add 1% more burden on the common. That's not enough to turn it into muddy wasteland, surely? But you would get a benefit of 20% more sheep for your household. That's a big benefit for such a tiny disadvantage to the common. You can't resist it, and the next day you buy another sheep.

But what happens when your neighbours notice? They want an extra sheep, too. They also do the maths and realise they can have a huge extra benefit to their household whilst only placing a small burden on the common. Soon everyone has 6 sheep each, and now the common is supporting 120 sheep rather than the 100 it can sustainably manage. In fact some people think they could probably keep 7 sheep on the common, and maybe even a cow.

Within a year all the grass on the common is grazed away. The feet of the sheep (and the cows and, for some reason, a kangaroo) poach the earth, churning it up and preventing the grass from re-growing. When the rain falls the common becomes a mudbath. When the sun shines the mud turns to dust. When the wind blows the dust blows away. Where once there was a fertile pasture capable of supporting 100 sheep and 20 families, now there is a barren dustbowl.

This little parable is often used to explain why nobody takes care of things that nobody owns. Our atmosphere, our seas, our fish stocks, old growth forest, the climate - each of us can get a big benefit whilst causing only a small amount of additional burden on these things, these commons. But 6.6 billion people on the Earth are placing too much burden on them, and if we don't stop we could end up with a dustbowl planet, incapable of supporting human life.

Economists argue about the solution to the tragedy of the commons. Some claim that everything should be owned privately - if the common in the parable was owned by a landowner who leased it to the villagers then they would not be able to overgraze it. But how can anyone own the atmosphere or the climate? Other people want governments to restrict people from over-exploiting the commons by enacting laws against pollution, overfishing and so on. My preferred solution is for individuals to take personal responsibility and control their own behaviour for the common good, for example by cutting their carbon footprint, buying local food even if it is more expensive, and avoiding over-consumption in general. But I always was hopelessly idealistic.

15 comments:

Joyce said...

This is great analogy!

Mjohnson said...

It is a nice analogy, but I don't agree with your solution, you admit you are hopelessly idealistic.

This is why the Green Movement has failed. This country seriously lacks politicians with any kind of direction, the Conservatives don't even have any policies. There is a massive gap in the market for the greens, but all they offer is sermons. What if a politician stood up and said

'We will build a barrier over the Seven to generate electricity and jobs, we'll pay to develop hybrid cars, which will reduce pollution and indusrty. We'll become a world leader in wind power, export technology, electricity and create jobs. We'll become a world leader in organic agriculture, we'll become the world leaders in sustainable architecture. We will have a zero carbon economy creating a sustainable, secure, nation with a real platform for wealth rather than the mirage of wealth offered by the financial services sector.'

Maybe people would vote for that, but all we get from the Greens is make sure you all switch your lights off, that's not leadership that's delegation, and that isn't going to help make our economy secure and competitive.

gregra&gar said...

The idea that man was granted the earth for his own exploitation by the creator of it all is the core assumption behind the total abuse we have wrought upon our environment. The idea that it can be owned was so foreign to native Americans that white men stole the land right out from under them. They didn't even know what ownership was until fences began being erected. Better held sacred than owned.

Yellow said...

I agree with Mjohnson's point about it beaing idealistic. But without ideals we'd all do whatever the heck we liked. Just because my neighbour throws rubbish on the pavement it would never ever ever make me inclined to do the same. My father is a huge figure in my life, and he influenced his three daughters with his ideals. That one man altered the thoughts of his wife, and of at least one of his brothers, and his three daughters. I know I have made my own husband re-think some ideas, and my two children will hopefully follow in my footsteps. Stoney, and Bean Sprouts make me think all the time. Last week I saw a 'right-on' looking woman buy organic carrots in Morrisons instead of the others. I asked her if she'd looked to see where they were grown. She saw they were from Israel, and I explained brielfy about food miles. I then laughed and said it's a lot to take in, and sometimes it's just too much to think about, but it is worth considering. Ideals are great.

Jen said...

I love this post. Idealistic maybe but common sense too (pun intended).

Mjohnson said...

I'm a bit embarrassed about my sermon on sermons. There's plenty of room for great things like this blog to inform people who want to live greener lives, but I also think we need strong political leadership for the macro projects which are vital if we're going to make the big leaps we need to make.

Melanie Rimmer said...

That's OK MJ. I'm always happy when Bean Sprouts stirs up strong reactions and feelings. I think the Green party has more macro projects than you give them credit for, although they do lack strong leadership - by definition, really. More importantly they lack any electoral credibility. They're more of a lobby group than a political party.

Politicians will do whatever you tell them. Well, they'll do what enough people tell them anyway - it's a numbers game. If you feel strongly, write to your MP and ask them what their environmental priorities are. Tell them what your own priorities are and let them know you'll vote for whichever candidate convinces you they're serious about green issues. People are already starting to talk green to politicians and that's why the politicians are talking green back. Do you think they decided to do that all by themselves?

So I still think it comes back to individuals. Not just changing their lightbulbs, but changing their consumption patterns, changing their voting patterns, changing their behaviour in lots of ways. I refuse to throw my hands up and say "I can't do anything by myself, I'll wait for the government to do something about it". You inspired me to write a new blog post about just that. It's called I believe...

Mjohnson said...

Oh hello Mel - I didn't notice your response. You're right, the message about the power of the individual does extend to politics. If you involve yourself in politics you really give yourself a disproportionately large voice.

Also I do hope you don't think that I am opting out of my personal responsibility. I am still concerned about my personal impact, but I think that all our collective hard work can still be wasted if our politicians don't make the right choices.

Killi said...

Te old Gypsy view: "We borrow the earth" is very apt here

maria said...

I completely agree with you, I'm sick of hearing people complaining about what the government is or isn't doing while all the time they could make the change themselves. The goverment is only trying to think of things to do because we haven't taken responsibility for things ourselves..

Anonymous said...

individual self-interest always outcompetes group-oriented behaviors, therefore exploitation beats idealism within any group. However, idealistic groups outcompete exploitative groups. The only issue is that we are all in one group when considering the atmosphere so there is little advantage to being more prudent as all you will be doing is essentially giving more exploitation opportunities to the selfish. You need to have some form of policing mechanism to curtail exploitation. You should probably read the actual paper that made up this example (Garret Hardin, 1968). An solutions to the problem in the biological literature (google: Altruism's unexplected ally). That provides some interesting insights.

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