Donald Trump’s recent flip-flopping on whether to allow the importation of elephant hunting trophies into the US has led to people taking to Twitter to put forward the economic case for hunting as an aid to preservation.

The argument goes like this:

1. If elephant hunting is allowed then people will come to hunt elephants
2. This brings money into local economies
3. It’s therefore in the interest of locals to preserve the supply of elephants

This seems pretty straightforward and irrefutable. Nobody wants to kill the goose that lays the golden eggs (unless it would look really good mounted on your wall). Where it comes unstuck – the argument, not the goose-head on your wall – is with an economic theory called the tragedy of the commons.

As a named theory the tragedy of the commons has been around since the 1830s, but it’s essentially a re-writing of a principle that is familiar to non-economists; left to their own devices people are dicks. When there is a shared resource people act in their own self-interest, even if doing so will harm the long-term interests of the group as a whole.

It happens on a large-scale – such as the, seemingly inexhaustible, supply of North Atlantic cod, which we fished almost to be point of extinction – and it happens on a small-scale; we’ve all worked in an office where a little perk has been removed or regulated, because some people take the piss.

As the old joke has it, when something is needed by everyone, and could be done by anyone, most of the time it’s done by no-one.

Helmer himself shows exactly how this works. On literally the same page of his Twitter timeline as the quoted tweet above he retweets the message at the top of this image:

Here he’s RTing someone who’s arguing that because we’re not the major contributor to oceanic plastic waste – the oceans being, of course, a huge shared resource – we shouldn’t be doing what we can to help solve the problem.

This is the tragedy of the commons writ large. This is the individual rationalisation that the problem isn’t with me, it’s with all those other bastards who are much worse. This is the logic that would, one day, lead to somebody whose wallet is far fuller than their soul pointing their gun at the last wild elephant and telling themselves, as they pull the trigger, that they’re no worse than the thousands who did the same thing before them.

Yeah, they don’t call it the tragedy of the commons for nothing.