Eine grüne Wiese ist in vier Rechtecke aufgeteilt auf der Kühe stehen. Das Rechteck unten rechts zeigt einen braunen Boden. Neben der Wiese steht rechts ein Mann und links eine Frau, beide sind in Arbeitskleidung und Gummistiefeln.



—— Over-fished oceans, clear-cut forests, over-grazed pastures: humans mercilessly use and over-use resources. What’s behind this irresponsible behavior—and how it can be contained.


Back in 1833, the British economist ­William Forster Lloyd observed a behavior that continues to characterize many of the world’s problems to this day. Lloyd noticed that numerous pastures accessible to the general public, known as the commons, were in a pitiful state: the grass withering, the land covered with cow dung, the cattle emaciated. Lloyd found that the reason for this over-use was the individual desire for profit without regard for the long-term consequences, a situation that he termed the tragedy of the commons.

One Quandary, Many Tragedies

In 1968, the ecologist Garret Hardin revis­ited Lloyd’s idea and wrote an article entitled “The Tragedy of the Commons.” Hardin’s sobering conclusion: ultimately, free access to public goods leads inevitably to their ruin. Scientists have been using the concept since then to describe very different situations. For example, overfishing of the oceans, the clear-cutting of forests, the polluting of waterways, the poaching of wild animals — even climate change — can all be traced back to the same quandary: although people act rationally at an individual level, their behavior ultimately harms themselves. In the fishing industry, for example, the catch for all fisherpeople initially increases, but then decreases because the fish stocks can’t recover and regenerate fast enough.


In an ideal world, every farmer only sends as many cows to a public pasture as that pasture can accommodate. For instance, a pasture has space for forty cows. If the farmers keep to this limit, the grass grows quickly enough and the cows do well. In the short term, the pasture could also feed more cows, but over the long term this would cause the pasture to degrade and would ultimately destroy it.


Farmer McDough is also aware that the pasture only has enough space for a maximum of forty cows over the long term. But she needs money to repair her house, money she can earn with a larger herd. To strengthen her position, she sends forty cows out to pasture and hopes that Farmer Smith will only send twenty. She would then have the advantage.


Farmer Smith knows that the public pasture can only feed forty cows over the long term. But he also knows that he would earn more money with a larger herd. What Farmer Smith doesn’t know is how his neighbor, Farmer McDough, will behave. In the hope that Farmer McDough only sends twenty cows, Farmer Smith sends forty cows onto the pasture. That will benefit him over the short term


Farmer McDough and Farmer Smith are both following the same logic: to secure a private advantage, they risk the over-grazing of the public pasture. However, the result of each individual’s rational thought experiments harms both parties in the end: the grass doesn’t grow fast enough, what remains is a muddy pasture and the cows of Farmers McDough and Smith end up starving.

Pathways Out of the Tragedy

1. The traditional approach is the allocation of property rights. A fence divides the pasture. Farmer McDough and Farmer Smith are individually responsible for their part of the pasture, which changes their thinking. Long-term security now outweighs short-term gains. Both only send twenty cows to their parts of the pasture. Yet property rights cannot always be allocated and enforced every­where. What works for a pasture often fails when it comes to deforestation in the rain forest because of the sheer size of the forests.

2. For some goods and areas, international law doesn’t provide for ownership. The atmosphere, for example, or a large part of the oceans, known as the high seas, belong to no one and everyone simultaneously. In cases such as these, international agreements have been established that, for example, set fishing quotas for the oceans or limits on carbon dioxide emissions. The problem with this is that those who ignore the quotas needn’t fear any punishment, as most agreements are voluntary.

3. A third way out involves neither the state nor property rights. As the Nobel laureate Elinor Ostrom has shown, some communities manage to use public goods in a sustainable way. For this to succeed, certain conditions must be met, for instance mechanisms for sanctions, community decision-making or mutual control. Only when members of a community take responsibility for their common resources can the benefits be sustainable for everyone.