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The Prisoner's Dilemma = America's Gun Dilemma

The evidence is overwhelming that guns are an American curse.

This is the second post in a series about America's disastrous gun epidemic. Here is the first.

We have a gun problem. One way to conceptualize its origin is via game theory, specifically the Prisoner’s Dilemma, as follows. Each person has a choice: Carry a gun or don’t. The best option, for each – and for society – is “don’t.” Not only would everyone save money, time, and anxiety, but no one gets shot. But here is the dilemma: Even if you agree that a gun-free world is better than a gun-toting one, you might worry that someone you meet might not feel similarly, and might therefore be carrying a weapon. If so, then you could be at a lethal disadvantage. So, you reason that you need a gun, too, if only just to protect yourself.

But that’s not all. Being a rational person, interested in doing the best for yourself, you might also be tempted that if someone you are likely to meet will be unarmed, you could take advantage of her restraint by carrying a weapon yourself, so that you could intimidate her. And so, whether to defend yourself in the event that someone else is armed, or to take advantage of her if she isn’t, you get a gun. This reasoning works both ways, and as a result, both of you end up armed.

The dilemma is that as a result, each of you is worse off than if you had figured out some way to cooperatively refrain from carrying guns — that is, if society had stepped in and instituted some form of responsible gun control.

It can happen, and in New Zealand it did. Immediately following the mosque massacre in March, 2019, when 51 people were killed and 40 injured, Prime Minister Jacinda Ardern announced “our gun laws will change,” and less than a month later, they did: The Kiwis outlawed all assault weapons, instituting a buy-back program to facilitate compliance. All but one of the country’s 120 national legislators voted for these changes, which allowed exceptions for commercial pest-control operations and licensed heirloom collectors (who will be required to render their items non-operational, storing crucial parts in a separate location).

By contrast, in the United States – which has the highest rate of gun deaths of any technologically advanced nation – gun laws have generally been weakened even as the country has endured massacres in Charleston, South Carolina (9 people at a bible study group), Las Vegas (58 concert-goers), Newtown, Connecticut (26 first-graders and teachers), Orlando (49 people in a nightclub), Parkland, Florida (17 schoolchildren and faculty), Pittsburgh (11 synagogue attendees), Dayton, Ohio (9 deaths), and El Paso, Texas (22 deaths) – the last two on the same day in 2019. This refers only to mass murders; the total American carnage on a personal, interpersonal, and within-family scale is substantially higher.

In many states, it is easier to buy a military-style assault weapon than to adopt a kitten from a shelter; in every state, the requirements for getting a driver’s license are stricter than for having your own gun. This, despite the fact that in addition to having one of the highest gun-related murder rates in the world, the data are clear that even modest gun laws are effective in reducing gun deaths. Case in point: Australia experienced a mass murder in 1996, when 26 people were killed – apparently at random – in Port Arthur, Tasmania, by a lone gunman using an AR-15 military-style automatic weapon.

An enraged populace, backed by police chiefs around the country, encouraged lawmakers to act – which they did. Within weeks of the tragedy, each Australian state and territory had banned assault weapons, including semi-automatics, while the national government banned the importation of these devices and also initiated an aggressive (and generous) buy-back program. According to Fortune Magazine[i], “a land of roughneck pioneers and outback settlers, Australia had never embraced much government regulation and certainly not about their guns. This was a land of almost cartoonish toughness and self-reliance, home of Crocodile Dundee and Australian rules football. Here even the kangaroos box.”

The result of Australia’s crackdown? During the ensuing 22 years, there has not been a single mass shooting. By 2014, which appears to be the most recent year offering such data, the murder rate was nearly halved, to 1.0 per 100,000 population, which is less than one-fifth that of the US, and of these, just 32 were committed with handguns. In addition, gun suicides in Australia dropped by about 80%.[ii] Australia’s population at the time was 24 million; by contrast, during that same year, Chicago – with a population roughly one-sixth that of Australia – registered more than 500 gun deaths.

Two states within the US offer an interesting contrast, essentially a case of differing experimental conditions. In 1995, Connecticut firmed up its gun licensing laws, establishing “permit-to-purchase” legislation; during the following decade, firearm homicide rates declined by 40%. It might be argued that this reduction was due to diminished lethal violence generally, but during this same period, non-gun homicides in Connecticut remained statistically unchanged.[iii] Almost certainly, making it more difficult to obtain a gun made it less likely that people would be killed by a gun. Missouri is the contrasting example.[iv] For decades, the Show-Me state had a permit-to-purchase law, requiring a background check that included in-person appearance at a local sheriff’s office. Then, in 2007, this law was repealed.[1] Between 1999 and 2006, the gun-related homicide rate in Missouri had already been 13.8% higher than the national average; after the repeal, from 2008 to 2014, it skyrocketed to 47% higher.

Of course, correlation is not causation, but in conjunction with the Australia experience, as well as the contrasting example of Connecticut, a strong case is evident. "Within the United States,” writes David Hemenway, director of the Harvard Injury Control Research Center, “a wide array of empirical evidence indicates that more guns in a community leads to more homicide.”[v]

In response, rather than tightening its gun laws, the Missouri legislature adopted an amendment to the state’s constitution that declared gun ownership an “inalienable right.” In that state, a 19-year-old cannot buy liquor but can legally purchase and carry a concealed handgun. The day following a mass shooting in Odessa, Texas, a new law went into effect in that state, loosening controls on whether people could bring guns to school parking lots, houses of worship, and the like.

And when the next mass murder occurs, legislators – mostly Republican, but some Democrats, too (especially those representing rural constituencies) – will doubtless offer the ritual “thoughts and prayers,” but nothing else.

David P. Barash is professor emeritus of psychology at the University of Washington. His most recent book is Threats: Intimidation and its Discontents (2020, Oxford University press).


[1] Background checks are still required for in-store purchases, but not for private transactions, including at the ubiquitous gun shows.


[ii] 2012



[v] Hemenway, D. 2017. Private Guns, Public Health. Ann Arbor, MI: University of Michigan Press