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Does deterrence work?

Joshua Keating asks today, "what does deterrence even mean, really?" It's a good question for at least two reasons: (a) deterrence against what? and (b) what's the evidence?

The first question is critical. The most famous case of deterrence is the MAD doctrine during the Cold War. It worked! But in the modern world deterrence more commonly means the ability to stop actions short of war, such as terrorism, limited missile attacks, and so forth. The most recent example of this is a clear failure: Hamas's October 7 attack on Israel obviously wasn't deterred even though Israel has a fearsome reputation for revenge.

So even if we accept that countries think twice about starting wars they might not be able to win—like, say, Lebanon invading Israel—there's still the smaller stuff to consider. This is where evidence becomes so important.

This is pretty easy to understand. For example, Donald Trump assassinated Qasem Soleimani, the head of Iran's Quds force, and his supporters like to say this kept things quiet for a while. But did it? The evidence is pretty equivocal:

Days after the attack, Iran retaliated by firing about a dozen ballistic missiles at two U.S. bases in Iraq. While no U.S. service member was killed, more than a hundred American troops suffered brain injuries as a result of the Iranian response.

....“There have been subsequent incidents including in March when Iran-backed Iraqi militia rockets killed two Americans and a Brit. The Iranians also used their small boats to swarm U.S. Naval vessels in April — without any apparent U.S. response,” [Barbara Slavin] said.

So maybe it worked and maybe it didn't. Can you ever really know? This gets us to the big problem of empirical deterrence research. If something happens, it's easy to say that it wasn't deterred. But if nothing happens, does it mean something was deterred? That's much harder to say.

This sets up a huge bias in favor of ever more deterrence. You can always point to attacks as evidence that we need stronger deterrence, but it's exponentially harder to point to nothing—or, harder still, a little bit of something but not very much—as evidence that we already have plenty of deterrence.

But after 9/11, the US made no mystery of its purpose. It was not to deter al-Qaeda, it was to destroy al-Qaeda. Ditto for Israel after the Hamas attack. In both cases, the countries involved decided that their foe could not be deterred.

And that seems to be the case generally for guerilla wars, insurgencies, and terrorist attacks. Even the threat of massive retaliation doesn't stop them. Nation states can be deterred from flatly starting a war with a superior power, but neither they nor anyone else show much potential for being deterred from anything else.

14 thoughts on “Does deterrence work?

    1. rick_jones

      Not sure if you will see this... while I don't recall the substance of the bet we had, I do remember that I lost. And so I dutifully send five bucks (or perhaps it was the then USD equivalent of five euros...) to Mother Jones. Of course, now they are sending me snail mail (from a zip code in New Jersey) seeking more. At the time, for the donation I included "In The Name Of D_Ohrk_E1" - and that is being echoed back in the addressing of the envelope.

  1. iamr4man

    Perhaps we’ll get to see if deterrence works. If Trump becomes President again and removes our forces from South Korea we’ll get to see if Kim Jong-Un attacks South Korea. If he doesn’t we can figure our troops there weren’t a deterrent. If he does we can say they were.
    I suppose we can see the same type of thing when the US withdraws from NATO. Of course, if Biden is still President we might never know for sure.

  2. TheMelancholyDonkey

    But after 9/11, the US made no mystery of its purpose. It was not to deter al-Qaeda, it was to destroy al-Qaeda. Ditto for Israel after the Hamas attack. In both cases, the countries involved decided that their foe could not be deterred.

    The problem is that Hamas and al Qaeda can't be deterred, but there is also no evidence that they can be destroyed. This is pretty much true of all guerilla armies. If you want to solve the problem of these sorts of actors, the only way you can do so is by winning over the population they immerse themselves in.

    That's hard. In many cases it may not be possible. But, if you actually want to eliminate the terrorists, spending decades immiserating those populations in pursuit of them is grotesquely counterproductive.

  3. Justin

    Revenge is sweet. Perhaps they not 100% effective as deterrence forever, but threats, justice, revenge, retaliation, and punishment are facts of human nature.

    Of course, the real problem with humans isn’t some kind of deterrence regime, it’s the propensity for violence. Why can’t we all just get along?

    1. Solar

      "Why can’t we all just get along?"

      Because certain psychotic individuals in society are always wishing for or cheering for the deaths of entire groups of people.

      1. Justin

        Punishing cheaters is critical to the proper functioning of civilization. The cheaters (Trump, criminals, terrorists, religious fanatics etc.) are immune to reason. When they choose to kill each other it’s best to stay out of the way and let them do it.

        What we all want is for people to stop committing crimes.

  4. sonofthereturnofaptidude

    There is research supporting the idea that retribution as deterrence is an effective strategy in competitions. It also works in human relationships more often than not. But for it to work on certain behaviors, the cognitive factors have to be taken into account. Behaviors that are irrational don't take costs and benefits into account. So the death penalty or other harsh sentences don't make much of a dent in murder rates.

    Nationalism drives fundamentally irrational behavoirs, so I think much of the time retribution as deterrence fails. It's not hard to get a bunch of young men to take up arms against another group of young men.

    1. irtnogg

      That shows up in classic game theory competitions. If you run a Prisoners Dilemma competition between different strategies, pure cooperation is a poor strategy, but if you prioritize competition while also providing for some retribution if your opponent won't cooperate, your strategy will be more successful.

  5. Salamander

    Hamas, al Qaida, Hezbollah and the like are more ideas than groups of individuals. You can kill the individuals, but the idea lives on, if the underlying injustices are not addressed. And if you kill lots of individuals, and very few of them are even from the offending group, the idea just gains strength.

    But what does this have to do with "deterrence"? My concept of deterrence is where a capability exists and is made clear, which prevents violence. Not beating the crap out of an unarmed captive population just before every election to show you've got the biggest swingin' ... well, you know what.

    Constant oppression with frequent bursts of ultraviolence isn't "deterrance." it's incitement.

  6. Jim Carey

    This comment contains mature subject matter.
    READER DISCRETION IS ADVISED

    To understand whether deterrence works, you first have to understand the elephant rules:

    Rule #1: Complain all you want about not being able to get anywhere without stepping in manure.

    Rule #2: Don't talk about the elephant.

    Rule #3: Anyone that mentions or implies that it would be a good idea to talk about how to get the elephant out of the room has really crossed the line.

    My parent's deterrents worked because I knew they had our family's interest in mind. The deterrents at the organizations I worked at worked when they served the interest of the whole organization, and not just senior management and the shareholders.

    If you want me to act in a certain way because it serves your interest at my expense, then you can stand me up at the gates of hell, but I won't back down.

    The elephant in the room is you can't understand anything, and I mean anything, without understanding what interest is being served.

    I apologize for breaking the rules.

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