A Young Person’s Guide to the Apocalypse


In a peaceful valley, in a tidy township, ten farmsteads surround a hypothetical pasture:

The pasture is such a perfect size that each farmer can graze exactly one cow there.  The addition of a single new cow would soon mean a decrease of about 9% in the resources available to each, including the new one. The eventual result of over-grazing would be resource depletion and devastation.

This story reminds us of a famous game-theory scenario, and we might be tempted to call it “The Pastoralist’s Dilemma.”  It’s clear what should happen:  if cows are limited to ten, then everyone will live happily ever after.

Sadly, this scene already has a different name, “The Tragedy of the Commons.”  This term is familiar from a 1968 article by Garrett Hardin, but the problem was identified in 1838 by William Forster Lloyd. Without some kind of intervention,  each farmer will be tempted to over-use a shared resource.  The farmer with a second cow sees an immediate, temporary increase in milk production of at least 81%.  This imposition upon others of the costs of one’s own actions is called an “external dis-economy,” or simply an “externality.”  This is an important concept in economics.

In this small example, where farmers are likely to know each other and would be able to see the results of their choices, it’s possible to imagine that some kind of Golden Rule could save them from catastrophe. Even in the larger world, enlightened management has sometimes encouraged sustainable use.  But a closer look at the map suggests two other, even more intractable problems.

For one thing, though it’s not indicated on the drawing, there’s a third dimension.  The atmosphere that lies above the Commons, and every parcel, extends beyond the boundaries of the map.  An owner may generate pollution that is invisible and thus difficult to trace, or so small in quantity that it seems negligible.  But the entire atmosphere is ultimately available to each polluter. The people in the neighboring township may be ironmongers rather than farmers. 

Second, a creek crosses from the north of the diagram through various parcels and through the Commons, providing water and other amenities: rivers have often been made to provide power or to carry away wastes.  Though the over-grazer risks the criticism of all the other farmers, a river is shared in a different way. Withholding water, or polluting it, may adversely affect only those downstream, and their relationship is not reciprocal. It may be difficult to hold an upstream polluter accountable. Also, although in our example the delay is slight, downstream damage occurs at some time after the upstream use. One can see the river as a metaphor for time itself.  The consequences of abuse may not be observed immediately.  A later generation has no remedy for the diseconomies visited upon them by their elders “upstream.”


In our little valley, farmers who were well-intended, and sufficiently well-informed, could band together to make sure that the actions of an individual would not bring them all to grief.  Here though is the cast of characters one is likely to encounter::

The Innocent.  Humans interacted with each other for centuries before noticing that the Earth’s resources might not be unlimited. The pressures of daily existence may seem to dwarf the problem of sustainability. Waste disposal is, historically, the process of hiding our externalities from ourselves.  A particular person may honestly just not have gotten the word; some may deliberately avoid information.

The Insignificant.  With only ten parcels, the problem and the solution are obvious, but as the number of users increases the ratios change.  As the Commons becomes large, the added value of the owner’s second cow approaches 100%, and the harm to each other farmer may seem too small to fight over.

The Faithful.  A farmer who sees Nature’s Bounty as Divine Providence, or as reward for human effort, will have no reason to understand the algebra of limited resources.

The Ideologue.  The second cow is the moral justification for capitalism:  the supposed result of investment is an increase in the size of the economy, which is said to mean greater opportunity for all.  Someone who is opposed to regulation in principle is unlikely to consider the need in a particular situation.

The Competitor:  Some people may glorify competition,  or want to outshine others in materialistic terms.  A parent may prefer to leave to a child not a better world, but a larger portion of a world that is worse.

The Discouraged.  The same calculus that makes an individual’s burden on the environment look small also makes it hard to see what positive difference an individual can make.

The Business.  Corporations have been endowed with many of the powers of humans, but they do not have the same interests.  Shareholders expect management to maximize profits, disregarding externalities.  Management may be forbidden to consider non-financial factors.  Governments are accustomed to catering to the demands of business.

The C.E.O.  People making decisions on behalf of corporations often have their compensation tied to short-term performance, so there is an incentive not to consider long-term effects even on the corporation itself, let alone on others.

The Deceiver.  Humans too are likely to separate their financial interests from their personal concerns, and may be willing, for personal gain, or when paid by another, to work at keeping people from understanding or solving problems. Social media companies make it possible to mislead other people without intending to.

The Distant.  Consumers have little control over where their milk comes from, or how it is packaged — someone else is making economic decisions on their behalf.


[This guide copyright 2022 by Scott C. McKee]