Regular EconLog reader Kevin Corcoran sent me the following, which I, with his permission, edited slightly.

I’ve been catching up on EconLog and I noticed your post on why sanctions rarely work. It reminded me of something from my time in the Marines: a different application of a similar idea. It helped lead me to my belief that collective punishment more generally rarely works.

You’ll probably be unsurprised to hear that the Marine Corps is big on collective punishment. If Lance Corporal Smith gets busted for underage drinking, it’s very common for the Gunnery Sergeant to punish everyone in Smith’s entire squad or platoon. The theory behind it is that if we all got punished for Smith, then we’ll all resent Smith for it and will keep him under close surveillance to make sure he doesn’t drink underage anymore, because we’d come to understand how Smith’s actions actually affect all of us. [DRH note: This reminds me of the motivation for Code Red in A Few Good Men.]

Of course, it never happened like that. Nobody ever resented Smith on account of the Gunny cracking down on everyone; they all just resented the Gunny and, if anything, would tend to rally around Smith. There are times when Smith’s actions actually, tangibly do affect everyone around him, but we already had incentives in place to apply social pressure to him if he was slacking in those circumstances. What the Gunny was doing was taking a situation that didn’t actually affect anyone (or at least not in a way anyone cared about) and make it start having a negative effect where none existed before. So, of course, the resentment went to the Gunny and not to Smith.

Worse, it actually created incentives for more people to engage in underage drinking. I tried explaining it to one of my Gunnery Sergeants when I realized it. Start with the idea that some rules are selfishly desirable to break: breaking them confers some benefit to the rule breaker. If you enjoy drinking, then breaking the rule against underage drinking confers a benefit on you: you get to do something you like that you otherwise wouldn’t. On the other side of the scale, if you get caught, you can get in various degrees of trouble and you might be willing to pass up the benefits to avoid that trouble. Now, add to the mix the idea that whether or not you’ll be punished for breaking this rule is no longer a matter of your actually drinking underage or not– you can follow the rules to the letter, but still be treated as if you had violated them. This significantly undermines the incentive to stick to the rules. If there’s a good chance I’ll be punished for drinking whether I drink or not, I might as well have a drink and enjoy the upside. Sure, you might get caught, but someone else might get caught instead of you, so why not at least have the fun you’re being punished for?

As an aside, the Gunnery Sergeant was not at all moved by a Lance Corporal telling him his punishment strategies were all wrong. Maybe this could have served as my “I should have known I’d be an economist” moment.

Well said.