What are some solutions to the "tragedy of the commons"?
Fixing the tragedy of the commons requires accountability or a common identity as well as a common resource.
The commons were a central pasture that was shared by all the people of the traditional English village. Because of greed many people wanted to graze more sheep than the common pasture could support. The common pasture was destroyed and in the end could not support any sheep.
One solution is accountability where each person is limited to the amount of the common resource that they can access. This often would require some level of government control.
Another solution is to have a common identity such as the successful Kibbutz in Israel. Individual greed is checked by a group identity where all the people of the community share not only the common resource but share the profits
Capitalism is a third solution. People pay for limited use of the common resource and the money paid goes into a common fund.
A fourth solution is to change human nature so that people are not selfish or greedy. This has not worked in the past. It seems from empirical evidence that mankind is not naturally good.