This is a model called the tragedy of the commons. Which should be called the problem with open access, since it has little to do with a commons. And tragedy is a kind of dramatic. Let's say there's some land with grass on it that people use as pasture for their animals. Nobody owns it and anyone can come and graze their livestock here. We're assuming that people don't communicate or work together. So we would call this an open access field. Let's assume the number of animals this field can feed is based on the quantity and quality of the grass, which is based on the health of the soil and it can only hold this many animals. This is the carrying capacity. If animals are added beyond this, the grass can't re-grow fast enough to support them all. Also the grass protects the soil from erosion. If too many animals are around eating the field may decline in productivity lowering the carrying capacity. The animals will be less healthy and provide lesser quality products lowering the profit each animal provides.
So it's in this group's best interest to keep the number of animals on the field at or below the carrying capacity. But every herdsman that puts animals on the field will get the direct benefit that that animal provides for them. But they would only share a portion of the costs of the degraded field. If the field were at carrying capacity and a herdsmen decides to add an extra animal. The added animals takes some of the food that would have gone to the others. This reduces their value. The owner of that additional animal comes out ahead because even though all his animals also are less healthy, he has more of them. But each herdsmen acts under these incentives and will keep adding animals to their herd or let their animals graze longer, so long as it's profitable to themselves. But really they are all losing out.
Kind of like the prisoner's dilemma. Contrast this to a situation where one person owns it. If they add extra animal, they're only hurting themselves so they don't do it. Since new people can't be excluded from using the field, there's almost no point in boycotting use because someone else could just come in. None of the herdsmen own the field and they can see the field may not be around forever. They see no point in conservation and just try to use it before someone else does. OK so we go on to can apply this model to unregulated open access fisheries, open access forests, an unregulated college dorm dish sink. But the problem with applying this model to the real world, is that we have to assume, among other things, that people don't communicate or work together. Which isn't true…. With a field like this, people will generally get together and make plans together and make plans about its use. They may act as a single unit, or just partition it sections, and they'll regulate the number of people that can use it. And if people are working together and communicating then it's not really open access.
It's not like every management situation is open access until somebody does something about it. So you don't tend to see the open access problem because people don't work together. You tend to see it in situations where people can't work together. The open access problem tends to appear not where people don't communicate or don't work together, but where they can't communicate or can't work together. Sometimes people are forced into a situation where they're not allowed to work together. Check out this video. Also the larger the management area is the more difficult communication and influencing each other becomes. For example the global management of greenhouse gas emissions tends to take on some open access properties. Basically this model is a way of communicating that: when people can't work together on a resource you call it open access..
. and it's bad. Which is why the model should have been called, the problem with open access. This episode is brought to you by, Hardin's canned animal meat. Now orphan free..