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How can we have less crime with less punishment? When Brute Force Fails

Internet hacker and activist Aaron Swartz committed suicide on January 11th, 2013. He was 26 years old. Swartz will be remembered not only for his enormous intellect but also for being a great person.

I was going through his website and came across his review of Mark Kleiman’s book on crime control strategies When Brute Force Fails.

Crime, aside from drug crimes (where his work persuasively argues that “the abuse of illicit drugs is a human tragedy but not a major threat to the social order”), is serious. (Presumably this only applies to classic violent crimes; it’s obvious this logic doesn’t work for violations of copyright law and civil disobedience.) Even where there’s a small amount of actual crime, it’s possible that’s just because people are wasting so much time preventing it. There’s a serious social cost to having to remember to lock our doors and carry our keys around all the time, let alone the money we waste on burglar alarms and car-tracking services and all the rest.

While I find the methodology he uses to show it wildly problematic1, I agree with his point that crime really sucks. Even if a burglar only causes $400 worth of damage, I’d pay far more than $400 to prevent a burglary — the loss of privacy, the sense of violation, the disruption of my normal order, the distraction of having to deal with police and repairmen and insurance agents, etc. all add up to make burglary a nightmare well above the direct economic damage it causes.

Such things are a frustration for white suburbanites, but for poor people stuck in the ghetto, they’re a nightmare. Crime is yet another disadvantage and a particularly noxious one at that. Even aside from all the other indignities suffered by the poor, just imagining life in a crime-ridden neighborhood is enough to make your skin crawl.

How can we have less crime with less punishment?

The first thing to notice is that low-crime is an equilibrium state: if nobody is committing any crimes, all anti-crime resources can be focused on anyone who decides to break the law, making it irrational for them to even try. But high-crime is also an equilibrium (assuming reasonable levels of punishment): if everyone is breaking the law, the police can’t possibly stop all of them, so it’s not so risky to keep on breaking the law.

To reduce both crime and punishment, you just need to tip the society from one equilibrium to the other. And, Kleiman argues, we can do that with a technique he calls “dynamic concentration.” Imagine there are three robbers (Alice, Bob, and Carol) and one policeman (Eve). Eve can only stop one robber at a crime, so if more than one person is committing a burglary at the same time, she decides to be fair and switch around who she arrests — sometimes she nabs Alice, sometimes Bob, sometimes Carol.

The problem is that the robbers know this and they know it means they only have a 1/3 chance of getting caught. A guaranteed arrest is bad news, but a 1/3 chance of getting arrested isn’t worth quitting over. So the robbers keep on robbing and the cop keeps failing to keep up with them.

But now imagine Eve adopts a new policy: dynamic concentration. Instead of randomly deciding who to go after, she goes after people in alphabetical order. So if Alice is committing a crime, Eve always goes after her first if she’s committing a crime — otherwise Bob, and then Carol. Now Alice knows that if she robs someone, she’s guaranteed to get caught (instead of just having a one-third chance), so she decides to sit this one out. You might think this would just lead Bob to step into the breach, but now that Alice is out, Eve can turn her focus to Bob instead. So Bob also decides to call it quits. That just leaves Carol, who Eve now gets to watch like a hawk, and so Carol also gives up the game. And there you have it: dynamic concentration stops all the crime without adding any more police.

Obviously things aren’t so clean in the real world, but I think this is the first game-theoretic argument I’ve read that seems to have some real force. Kleiman backs it up with some messier simulations and some real-life examples. Unfortunately, most are stories about cracking down on drugs or other unserious crimes like squeegee men, but the general point seems to work.

Still curious? Learn more about Aaron Swartz. Learn more about crime-control. My thoughts are with his family and friends.