In this post, I am going to explain the basics behind another common market failure, the tragedy of the commons. If you would like a more broad overview of what a market failure is, I have a previous blog post on that topic. If you want more deep dives on market failures, check out my posts on externalities and natural monopolies. Additionally, I won’t be going into any of the math behind this concept. Instead, this will be a more intuitive discussion of how the tragedy of the commons works and what its impact on markets is.
What is a “common good?”
Common goods are sometimes confused with public goods because they are both non-excludable and the public sector ends up intervening in these markets. The key difference between these two is that common goods are rivalrous, meaning that one person’s consumption of the good does prevent others from consuming it as well. A common example is a lake that people commonly use for fishing. It is largely impractical to exclude people from fishing on the lake, but if too many people fish they will overfish the lake and there will be no fish left in the future.
Why the tragedy of the commons happens
The “tragedy” in the tragedy of the commons comes from a mismatch between individual incentives and collective outcomes. Each individual user of a common good has an incentive to use as much of the resource as they reasonably can. If I am fishing in a shared lake, I benefit directly from catching one more fish. However, the cost of that extra fish (slightly reducing the fish population) is spread out across everyone who uses the lake now and in the future.
Because each person only experiences a small fraction of the total cost, it becomes rational for individuals to keep using the resource heavily, even when it harms the group as a whole. If everyone behaves this way, the resource eventually becomes depleted or degraded. In the fishing example, this could mean smaller catches over time, collapsing fish populations, or eventually a lake that can no longer support fishing at all.
Why common goods are market failures
Common goods lead to market failure because private markets alone often struggle to manage them efficiently. Since these goods are non-excludable, it is difficult to assign clear property rights or charge people directly for their usage. A competitive market would establish an equilibrium price where the consumers of the good are directly bearing the costs of consumption.
This leads to overuse, underinvestment in maintenance, and long-term damage to the resource. The total value society gets from the resource declines because there is no built-in mechanism to protect it from overuse.
How policymakers respond to the tragedy of the commons
Because common goods are vulnerable to overuse, public policy often plays an important role in managing them. One common solution is to create rules that limit how much individuals can use the resource. Fishing quotas, hunting seasons, and permits for backcountry campsites are examples of this approach. By restricting total usage, policymakers can help ensure that the resource remains available over time.
Another approach is to introduce forms of exclusion where they were previously difficult. For example, governments may issue licenses or permits that limit the number of users who can access a resource. In some cases, resources are assigned property rights, allowing individuals or groups to take responsibility for managing them. When users have a stake in the long-term health of the resource, they often have stronger incentives to conserve it. This has been a successful strategy for conservation of forest lands used for logging. There are also hybrid approaches that rely on community management. In some areas, local users collectively develop rules for sharing resources in sustainable ways.
With thoughtful rules, incentives, and oversight, common goods can be managed in ways that balance individual use with long-term sustainability. When done well, these solutions help preserve valuable shared resources while still allowing people to benefit from them.
