When defense is not a public good

Security measures that deter crime may unwittingly displace it to neighboring areas, but evidence of displacement is scarce. We exploit precise information on the timing and locations of all Italian bank robberies and security guard hirings/firings over a decade to estimate deterrence and displacement effects of guards. A guard lowers the likelihood a bank is robbed by 35-40%. Over half of this reduction is displaced to nearby unguarded banks. Theory suggests optimal policy to mitigate this spillover is ambiguous. Our findings indicate restricting guards in sparse, rural markets and requiring guards in dense, urban markets could be socially beneficial.

That is from Vikram Maheshri and Giovanni Mastrobuoni, forthcoming in Review of Economics and Statistics.  Via Peter Deffebach.


Why not? If I do the math correctly an extra guard anywhere reduces overall robberies by 35%*50% = nearly 20%. That's not bad.

Yeah... I can't see the path the finding of a net reduction in robberies to the conclusion of "Our findings indicate restricting guards in sparse, rural markets and requiring guards in dense, urban markets could be socially beneficial".

This is the standard nonsense leakage argument: "well it won't work all the time, so we should do it none of the time." It's a common refrain among gun traffickers opposing background checks and billionaire hoarders opposing tax accountability.

Leakage is a reason to revise a policy, not abandon it.

This appears to be the socialist mantra. To not allow anyone to defend themselves or their business so that crime violence happens to all.

Background checks = not allowing anyone to defend themselves.


It is curious that NRA-types always deliberately mishear that point. The whole point of gun-sale background checks is to prevent sales to criminals. I.e. to make criminal violence less threatening, and violent self-defense less necessary. But the NRA doesn't like that, because it means they'd sell less guns, both to criminals and people under threat from criminals. They sell the guns to both sides. And private gun owners don't like it because they want to be able to sell a gun on Craigslist and to not be liable if the weapon is used in a crime. They like having legalized gun trafficking, it's profitable.

I don’t necessarily disagree, but that’s not the steel man argument.

The idea is that with a federal background check system with no time limit failsafe, a Bloomberg administration would just refuse to fund it.

So guns would be legal technically but impossible to purchase or transfer ownership.

See also: third trimester abortion restriction laws. Hard to have rational policy in an age of partisan nutjobbery.

So let's not change anything ever because it could slippery slope into something bad or be gamed or worked around. Let's not try anymore.

Not sarcastically, exactly. Or maybe we should write concise laws with automatic mandatory sunset times.

Bob! The NRA does not sell guns. The purpose of the background checks is to infringe on a good given right that the government is expressly mandated to not infringe on. There are already laws to prevent/criminalize felons from acquiring guns. The background checks are designed to begin that criminalization process for people who can legally own guns.

That's exactly what I'd expect to hear from a creature that can shrug off machine gun bullets.


It’s a fairly standard argument offered on the left against jailing criminals.

There a lot of people in the America's against jailing violent criminals, then?

How about we prohibit governments from implementing the policy suggestions of authoritarian social engineers instead.

To make the question interesting one must hold constant the number of guards. But, there is still an answer: Randomize, young man, randomize! :-)

You mean our trillion dollar adventures in Afghanistan and Iraq created ISIS? You don't say.

It does seem impossible to murder terrorism out of existence.

Since circa 1980, the GOP has sought to privatize war into for profit business, claiming private for profit costs less, and delivers more, and faster.

Obviously, quick total victories in Afghanistan and Iraq prove the totally government run LBJ war in SE Asia should have been turned over to private for profit contractors.

Of course, US government regulations and mandates handicap US contractors. Bin Ladeen was free of OSHA so he did not need too protect the workers who were suicide bombers, and wasn't forced to pay high workman comp taxes.

(Seriously, the wars since 2000 have delivered far less at much higher cost against a far smaller enemy than the hot war part of the cold war against the far bigger, wealthier commies in the 50s and 60s. By all objective measures, the Saudi/Israeli axis of evil has humiliated the US, forcing US citizens into favoring isolationism and tolerating fascism globally.)

Note, total control over the global economy has been turned over to China while McConnell has been in the Senate as the GOP has privatize US industrial policy to the for profit private sector. Every factory in the US requires the approval of China to remain open or to be built, according to the statements made by the representatives of Trump and the GOP and their backers in the conservative intellectual elite.

It is weird that we defeated Imperial Japan while substantially contributing to the defeat of Fascist Germany, both over the course of four years (two of the most militarily advanced nations in the world at the time). But, fighting the exile government of one of the poorest nations in the world is now in its 18th year. Turns out there's much more money to be made in fighting a war, not in winning it.

How about not unnecessarily interfering with decisions of actors in free markets? Organizations are deciding whether guards meet a cost/benefit analysis in their opinion. Yes, their decision has an impact on other players in the market. Big whoop. You might as well ban restaurants serving good food (because it unfairly takes customers away from mediocre restaurants).

Mandating and banning guards are both stupid ideas. The latter would never happen, because what if you ban guards, and then a robber comes in and kills people? No politician is going to sign up to take that blame.

If you have a super itchy finger and must get the government involved, why not improve law enforcement to lower the incentive to rob banks in the first place?

Increasing law enforcement is functionally the same thing as mandating guards. Except the taxpayer is then paying to subsidize the firm's security costs, a huge tax subsidy for more robbery-prone businesses.

Increased risk of punishment is a deterrent, but it also requires more surveillance, data collection, and violation of personal privacy.

Mandating guards and increasing law enforcement is not the same thing. In the former, you're not leaving a mark. Businesses may or may not hire guards. Second, businesses open and close; guards come and go. Meanwhile, increased law enforcement stays; it sends a lasting signal.

I've often thought that the signs people put up about electronic surveillance of their homes may mainly be about encouraging burglars to go elsewhere. I wonder if the optimum would not be no individual surveillance and better policing foiled by externalities.

I would disagree. Reminding potential crime-doers about the risk of capture is a key tool for deterrence. It's why retailers put in a bunch of dark camera nodes, so you don't know where the camera is looking or if there's even a camera installed. Putting up pro-social messaging or even just a picture of a face can increase rule compliance and reduce deviant behavior.


Word on the street(*) is that intruders will break into signed/alarmed homes, planning to be gone in 15 or 20 minutes. Perhaps that limits the damage they can do.

One neighbor has a decoy safe to slow them down.

We have a barky dog.

* - homeowner word

What dan1111 said above. "Socially beneficial" my butt. As Hillary Clinton might have tyrannized, "We're going to take guards away from you on behalf of the common good."

That's why pro-2A states have less crime than states with strict gun control.

That's not why.

What till you hear about scarecrows

I have friends who post security system decals and signs at their homes. No, they don't actually have a security system but a would-be criminal doesn't know that. Many if not most security guards serve the same function: they are rarely well-trained in law enforcement. A life-sized cardboard cutout would do just as well. The "leakage" theory of crime (enforcement in one place just shifts crime to another) reminds me of the termite case. Many years ago I appeared in county court for some reason that I can't remember. As I waited my turn to be called, the case before mine was a debt collection case brought by a pest control business against a middle aged black woman. The woman, upon being examined by the lawyer for the pest control business, acknowledged consenting to the business's salesman to have the house tented for termites. Her explanation was that the salesman approached her as she sat of the front porch of the house and told her the other houses on the block were all being tented for termites, and if the house where she sat wasn't tented, all those termites on the block would come to that house. The judge intervened to confirm that the woman did consent to have the house tented. Yes, the woman answered, she did consent. Then why haven't you paid the pest control business for having the house tented, the judge asked. Because it's not my house, the woman answered. Case dismissed.

So, more guns less crime?

Shh! Don't tell Midget Mike.

ATF study: Private gun ownership soars to 423 million (17.7 million AR-15) privately owned guns; at same time violent crime rate declined 48.6% and unintentional firearm-related fatalities have declined by 68% (1993 to 2017). Bartozzi noted that “as lawful firearms ownership in America continues to grow, criminal and unintentional misuse of firearms is falling.”

Crime will not be reduced by disarming law-abiding Americans. Munchkin Mike needs to do what he did in NYC - stop and frisk.

Background checks = disarming law-abiding Americans.


Dick, look it up. US households with guns have fallen by about 30% from its peak around 1993. There are more firearms now, but they are concentrated in the hands of fewer individuals. Now I'm not saying these two things are related, but crime has declined with the decline in household firearm ownership.

Beneficial to who?

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