The theory known as the Tragedy of the Commons was first postulated by British economist William Forster Lloyd in 1833, but it was popularised by the American philosopher Garrett Hardin in 1968 in an article in Science Magazine. It is now widely used in the field of environmental studies.
So what is it?
Imagine an area of common grazing land. By common, I mean it is owned by everyone, rather than by an individual. Such common areas have been a feature of European culture since mediaeval days. Now, the population at large enjoy grazing rights and are free to let their cattle graze on the grass growing on the common. Furthermore, it’s a good use of the grass because otherwise it would have to be cut by machines and taken off-site for hay storage.
Over the years, more and more people take advantage of their grazing rights on our imaginary common and the number of cattle put out to graze there grows steadily. Then one summer, there are just too many cattle grazing and all the grass is eaten long before the winter comes. The common land turns to mud and the cattle starve. The land has been overgrazed. What a tragedy we have cooked up here – we've been undone by our own greed!
Well, technically speaking, this is not a tragedy at all, it’s a balls up, but let’s not get too Shakesperian about this. It’s known as the Tragedy of the Commons and the name has stuck.
So what to do about it? The basic question is to first work out what the sustainable level of cattle grazing is for our common. Say, for argument's sake, it is 25. 25 cattle on the common in the summer and everything stays hunky dory. But put 26 on it and, pretty soon, the grass can't keep up with all those hungry cattle. So a logical approach here would be to limit the grazing rights to 25 cattle. This is where it gets tricky.
Who decides which 25 cattle get to graze the common? You could do it by drawing lots, but what then would the unlucky losers do with their cattle? Sell them on? Or hold out for a better draw next year?
Alternatively, you could sell grazing rights to the highest bidders – but then it has stopped being common land. Or maybe you could subdivide the common into 25 plots and sell the land. Then it’s called enclosure and you have really moved way away from the common ground idea.
By and large, when it comes to land ownership, we have as a planet moved away from common grazing rights towards private ownership as a solution to this conundrum. You could sort of see the history of agriculture as being mostly about enclosing common land. The fence is the enemy of the common. But there are lots of assets (the oceans? the atmosphere?) which can’t be divided up like this and where we have to work out a common destiny in order not to queer the asset.
It’s not hard to see how this question plays out in a world of many billions of people. It is just possible that our planet can cope very comfortably with, say, 3 billion people living a Western lifestyle enjoying full bellies, good housing, social security, pensions and foreign holidays, but that at 10 billion the grass will stop growing and we will all fall out of bed with a bump. Yes of course it's possible. It is quite likely even. But how would we know where the sustainable boundary is? It is not as though we will find out in the course of one summer's grazing.
We move here into the subject of planetary boundaries which explores just where our limits may lie. The most sophisticated model for this hails from Sweden. Planetary Boundaries: the Stockholm Resilience Centre.
They suggest there are 9 boundaries of which climate change is but one. But, as with the cattle on the common, it is one thing to identify just how much developmental pressure our planet can take, quite another to decide how to implement best practice. It is horribly compromised by us having divided the world up into a series of nations who jealously guard their own boundaries. Some countries (Russia, Canada) are well equipped to deal with planetary changes and resource depletion. Rather more countries are poor, have high populations and are very vulnerable to shifting climates.
Environmentalists like the metaphor of the Tragedy of the Commons because it sticks it to the neoliberals. It's a great example of market failure and it cannot be sorted out without some form of political intervention. The planetary boundaries are real enough and the technical solutions are understood. But what actually happens is all down to politics. And international co-operation-type politics, something we are very poor at.