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Marco Carbone

A cost-benefit argument for preventive war is quite convenient when you can pick and choose which costs you think are worth discussing. As some of the comments above have mentioned, you do this discussion a disservice by not discussing other potential costs of preventive war, such as appearance of illegitimacy to other nations, the inability to sufficiently defend the decision to one's people, the loss of civilian or other life on either side, etc.

Now, if your post was meant to be an introduction to utility theory, then you hindered your intent by clouding a theoretical discussion with a political angle. It works nicely for you because if anyone criticizes your post, you can claim that they're criticizing the underlying theory, not the conclusion. But your post greatly simplifies any sort of analysis needed to justify preventive war (which I'm not claiming to be unjustifiable) by implying that the most important costs can be enumerated and computed with sufficient reliability.

For a more thorough and rigorous discussion of these matters, check out William T. Vollmann's 7 volume treatise on when violence may or may not justified, Rising Up and Rising Down. You'll find a careful analysis on the kinds of costs one can incur by the application or witholding of violence. For example, your post, Judge Posner, implies by omission that costs can be tallied linearly. But things are not that simple when considering civilian life. Is it justified killing 100 of our enemy's civilians to save 10 of ours? What about 1000 for 100? Or 100,000 for 1000? Or 1,000,000 for 100,000? Or 1,000,000 for 100? You can't just plug these numbers into your basic utility theory equations.

L. Lhuilier

The concept of preemptive war based on a cost/benefit model is rather suicidal. Since that same model will be used against those willing to engage in preemptive war.

The learned scholar Prof. Becker of the University of Chicago wrote the following about those involved in these suicidal attacks:

The only really effective approach is to stop them before they engage in their attacks. This is accomplished by tracking them down and imprisoning or killing them based on evidence that they intend to engage in suicidal attacks. Those planning such acts can also be punished on the basis of intent.

So how do you prevent these kind of escalations where one professor professes his intend to kill the other? And they are even supposed to be collegues and friends, running a blog together!


Wow, that was underwhelming. I could've read this on Instapundit. All of this analysis is based on a one-time game. But intervention itself creates conditions for future, subsequent "blowback."

Also, the analysis of 1936 Rhineland is really really really weak. We can play hypotheticals all day and make the argument that if the French hadn't demanded exorbinant reparations in 1918, the German right wouldn't have used that

Or go back even further and say that if the U.S. had not intervened in 1917, Europe would have had to fight to a negotiated peace, which would've kept the balance of power more-or-less where it should've been. The U.S. intervention, and then (sensible) extraction in the 1920s, meant that the allies won the war, but couldn't win the peace.


One other factor that plays into this discussion is that war is almost never undertaken except after a major attack -- an event that the republic can accept as justification or pretext to do the job.

Names like 911, Pearl Harbor, Lusitania and the Gulf of Tonkin have all served that purpose. In the 1990's the US was attacked several times where the awfulness of the attack didn't reach the level that would allow any president to move into Afghanistan. Only after 3,000 people were killed on our shores could it happen.

The preventative war in Iraq could only be done with public approval after 911, even though the connection remains tentative. Democracies can only wage war when the people agree. That eliminates any possibility that Britain could have confronted Germany earlier. Even the early years after the invasion of Poland were known as the "phony war", since there was little appetite to pursue it aggressively. And we will not attack Iran or N Korea now, no matter what type of provocation until an actual attack begins.

So my feel is that this is a moot question. A democracy can't become involved in a preemptive war, except in very specific circumstances. Those circumstances include a violent shock to the nation, and a situation where there's a bad guy in the same part of the world that needs to be dealt with. Not a picture that will likely happen again.


Judge Posner, how would you factor into your equation the cost to global stability or peace generally. Isn't your formula necessarily state-centric? How do you interpret your formula in light of the goals of the UN Charter "to save succeeding generations from the scourge of war"?


As with MRL, I fell off the rails when I read "Indeed, the essence of self-defense is striking the first blow against your assailant."

I hope this is a phrase that would be remedied by editing - since what is described is in fact the essence of offense.

The essence of defense is to not be harmed - striking preemptively is one of many possible tactics, but is in no way the essence of the thing.


So, let's say I am Iran, or N. Korea, and I reasonably suspect, can put a numerical probability on, an invasion by the USA? By this rationale, I am justified in a pre-emptive invasion of N. America. Of course the theoretical economics argument is sound. It is the practical employment that makes no sense whatsoever.

Had you left out the references to Iraq, one might have been able to excuse this as a simple academic exercise.

Sometimes I wonder whether otherwise apparently bright individuals lose all sense of rationality when devotion to ex-post justification of the Bush Administration's war in Iraq takes over. Absolute failure to consider the situation from any other party's perspective than their own seems to be the hallmark of such thinkers.

Essentially this same rationale has been tried to justify our flaunting of the Geneva Conventions, with very likely adverse effect on the treatment of our own personnel.
I see that I am not the first or only person to see through the blatantly political agenda here.

This is a frankly embarrassing first post for two reputedly very smart people.

Jason Ligon

Concerning the ubiquitous 'blowback' principle of foreign policy, I would note that there is an assumption inherent in the argument that the choice to not act has no consequences, or 'blowback'. I can't see how that view is justified.

In general, I don't know that historical counterfactuals are useful tools in arguments about justification. They tend to be divorced from the perspectives of the affected parties. What level of reparations in combination with the loss of the WWI would be low enough that the German right wouldn't have seized on it for leverage? Who knows?

"The concept of preemptive war based on a cost/benefit model is rather suicidal. Since that same model will be used against those willing to engage in preemptive war."

Power escalations are rational in many cases for just this reason. International relations is fundamentally about the ability to inflict harm. It therefore behooves those with liberal values to be able to inflict massive harm on those without those same values. The justification may be made both ways, to be sure, but that point is moot. The reason Saddam didn't march on Washington was not that he felt in his heart it was wrong to engage in aggressive acts, it was because he was physically incapable of doing so.

To take preemptive action off the table is to surrender enormous strategic advantages, especially when dealing with a non localized threat. Every entity that can count itself as distinct from Al Qaeda gets a free shot at us in that scenario. Suppose bin Laden has a brother that runs a fundamentalist, anti West terrorist organization distinct from Al Qaeda. Do they have to blow up a couple of buildings before we are justified in attacking them? What if Al Qaeda breaks up and reforms into smaller groups with different names? If we kill or capture all members of AQ who were directly involved in attacking the US, are we done? Other members of AQ certainly didn't attack us.

Jason Ligon

"As with MRL, I fell off the rails when I read "Indeed, the essence of self-defense is striking the first blow against your assailant.""

A wise man once said, "What is true of the kung-fu fight is not true of the gun fight." If he didn't say it, he should have.

Real people don't dodge bullets, and the first bullet can kill you.

Rob W

I think that states sometimes use some sort of rational calculus to go to war. But Judge Posner's very number-crunching look at the subject seems to gloss over a key point--estimation of political and military forces on a quantitative basis is extremely difficult if not impossible.

If such estimation is impossible, then any theoretical justification based on an exposition of such principles at work is, to say the least, intellectually suspect.

Furthermore, the question as posed simply evades the moral dimension, one of the critical elements of any war analysis. I guess I might be called "old-school" in these days of realpolitik, but I think that preventative war is immoral.

More importantly, the analysis' only historical example is one where preventative war was decided against, creating a huge bias towards finding preventative war as useful. But examples of preventative war that led to ruin or did not create the benefits claimed abound in history--Stalin's backdoor move on Poland in 1939, or his invasion of Finland a year later. The biggest of these examples, Germany's invasion of Soviet Russia in 1941, is not touched on at all. Barbarossa was based entirely on a belief that eventually, Nazi Germany and the U.S.S.R. would come to blows and that now, rather than later would be the time to fight that war. To argue that Barbarossa was worth it is simply ridiculous.

But I think the best illustration of the absurdity of the concept is its application to every country on Earth. Imagine a "Preventative War Index" by which the Pentagon would measure the likelihood of attack from other countries and then use this matrix for decision-making. I can think of many small countries who are unlikely to do much damage to the U.S., but whose invasion would cause little grief to the U.S. Despite the fact of low risk of attack, it would still be cost-beneficial to attack these countries. However, I think that few readers would support invasions of Bhutan or Madagascar.


Presumably, the Pax Americana of the future leads our attention to a McCarthyism which threatens everything we hold dear. On the other hand, the unstated purpose of this war brings about the predatory imperialist aims outlined by the crypto-fascist Project for a New American Century. So far, the influence of Leo Strauss belies justifications given by the world's leading apologists for the essential Western imperial interests. It appears that the pro-Sharon neoconservative cabal brings forth this calamity brought to us by a horrific onslaught, known as Shock and Awe.

Kirk Parker (not the same as Parker above)

Paul Eremenko,

The rule against attacking a nation unless attacked Except there is no such rule. Posner made that point quite clearly right there in paragraph 1. Disgree with it all you want, fine--but I don't think you can fairly claim that Just War or some other widely accepted theory of international conflict supports your position.

John Hempton,

the assumption that Hitler would have been overthrown [in 1936] is too quick by farWell, we know for a fact that officers were planning a coup if Britain and France had decided to defend Checkoslovakia. German military strength was also far weaker in '36 (this is the main flaw in your alternative history.) Because of these factors, the assumption that Hitler could have been defeated over the Rhineland has always seemed very uncontroversial to me--though of course the general's plot was not known to the Allies at the time (it hadn't even occurred yet.)


Now that you mention it, "the essence of self-defense" statement is perhaps too condensed to be useful. How about "Without the ability to strike the first blow against your assailant if necessary, you certainly don't have self-defense, at least not as understood in the Anglo-American common law tradition"? That's certainly the mental context I supplied the first time I read his statement.


Although yours are good questions, there are some troublesome elements lurking right below the surface, most notably the apparent link you make between stability and peace. That seems pretty darned state-centric to me: quibble about the legality of deposing Sadaam, while never once accounting for all the Kurds, Marsh Arabs, and others harmed by the Baathist regime because that was all internal state affairs.


This topic is impacted by change in several areas.

Technology has escalated the destructiveness that even small groups of potential enemies can wield. This skews the complex preventative war calculations that many on this forum wish for - possibly to the breaking point. Another point of instability is the breakdown of the "nation-state mystique" that was so carefully bulit at the Congress of Vienna, namely the idea that the leadership of a nation is comprised of 'special people' who are not to equivalent to some nameless infantryman. Hence, the "no asassintaions' policy [Pay close atention: not Law, but Policy, which is a stroke of a pen].

Not only is preventative war seem to be growing more needful, its proper expression may well become the immediate destruction of a ruling elite as the standard opening move: Pawn to King4 = JDAM in the Beloved Dictator's bedroom.

Since this involves far fewer casualties and a potentially more odious target set, it is likely to be much easier to "sell" to the public.

This going to be an interesting century.

James Wetterau

Judge Posner: I wonder if you feel the exact same logic should apply in criminal trials for assault. Should the individual's weighted calculation of the costs and benefits of the risk from not preventively assaulting an enemy be considered, rather than more traditional standards for self-defense? If not, why not?

Is this what the "Burning Bed" defense is about?


As long as we are considering historical counterfactuals, let's go back to WW I and the consequences of America's intervention and the removal of the Kaiser.
US intervention delayed the exit of the Soviet Union and tipped the scales toward the Allies.
Without it, Germany probably would have won the war and the map of Europe and the balance of power would looked slightly different. Germany wouldn't have been a threat, as the GDP of the Triple Entente was 5% or so larger than that of Germany and the Austro-Hungarian empire combined, and wouldn't have been on the hook for reparations.
Since the Kaiser was a check on the rise of a dictator, Hitler wouldn't have come to power and so WW II probably wouldn't have happened.
Churchill accepted the logic of this.
As for Japan, if FDR had pursued a libertarian foreign policy and kept the navy within three miles of the West coast, its military wouldn't have felt compelled to bomb Pearl Harbor.
Hawaii was not a US state then, just evidence of America's nascent imperialism.

Freder Frederson

I would love to see your calculations for how much a baby's leg or thousands of dead and displaced civilians in Fallujah is worth in your cost-benefit analysis. How about a 19 year-old dead marine or his grieving mother? Or three years in Guantanamo Bay for a poor Pakistani who was in the wrong place at the wrong time and turned over to the Americans for a couple thousand dollars in bounty?

Or what is the cost I have suffered for being separated from my wife for the last six months? Not much compared to the examples above, but significant when you multiply it a couple million times.

War is a bloody, horrible, messy business. Preventative war will never survive a cost-benefit analysis because by its very definition preventative war can be avoided, and since you can't put a cost on human suffering (maybe you can, but I always found your decisions to lack any spark of human feeling), preventative war is never justified because there is always an alternative.

Deanne Mazzochi

A few "costs" that have yet to come up in the context of the Iraq discussion posts:

1) How do you account for the costs in human capital as a consequence of Saddam's extermination of his own countrymen? He had nearly a generation to squander the productive talents of the Iraqi people; his psychopathic sons were to be the ideal product of the next iteration of the regime. Doesn't there come a point where if you do not act preemptively, you may get to a point where the entity you are reacting against will never be able to recover?

2) The cost of securing total victory vs. long-term management of the problem. For all the comments re supposed facts that we did not acurately quantify prior to invading Iraq, I see far greater danger in not recognizing, or finishing conflicts to total victory, and believe that when in doubt, err on the side of securing victory. Would N. Korea have nucelar weapons today had Truman decided to "win" that war instead of accept a divided Korea? Would we have been better off deposing Saddam back in the early 1990s? What if Israel were allowed to keep and govern the territories that it won as a result of various wars initiated against it, rather than give them back to the very ones who call for the nation's destruction? What if Reagan had unleashed the full force of the Marines in response to the attack in Lebanon?

3) The cost of requiring a "rational" strategy of the U.S. when dealing with inherently "irrational" actors on the other side. Take preventative or offensive war off the table, or place a legalese framework on the decisionmaking process, you give far more leverage to your enemy.

4) Long-term strategic costs. Regarding the current threat from Islamofacism, one of the issues that needs to be addressed is attacking both its financial and ideological underpinnings. That is primarily coming from Saudi Arabia, with secondary effects (in terms of terrorist training methods and threat of nuclear capacity) from Iran and Syria. What are the comparative costs of overturning the Saudi regime directly vs. Iraq? Is it possible to have a successful regime change in Saudi Arabia when you have Saddam Hussein sitting on the border? Ditto with any revolution-from-within in Iran or Syria, were one ever to occur? Now that the US is formally entrenched in Iraq, with a presence in Afghanistan, doesn't that change the cost-benefit analysis (to render non-war options more likely) for surrounding nations vis. providing added inducements for self-reform that would never have existed had preemptive activities been off the table?

5) The "legitimacy in the eyes of others" cost is overplayed, and I think a false cost. All of the "others" are essentially free riders. Their opinions shouldn't count for much, if anything.

For what it is worth, I personally think that the problem with pure cost-benefit analyses, absent a guiding moral/philosophical component, is that cost-benefit analyses will ultimately work to the benefit of the person most likely to abuse them. Arguably France is the nation that has been most wedded to pure economic cost-benefit analyses in its Middle-East strategy; Saddam Hussein was able to manipulate that analysis all too well (see, UN Oil-for-food scandal, for starters). Is France's geopolitical strategy really the intellectual ideal we want our nation to strive for?


"Had France and Great Britain responded to this treaty violation by invading Germany, in all likelihood Hitler would have been overthrown and World War II averted."


The only thing that would have happened "in all likelihood" is that there would have been unintended, unpredicted, and unpredictable consequences.

It is just as likely, for example, that Hitler would have repulsed the invasion and increased the development efforts to produce the German atomic bomb .

The point is not that preventitive war is never justified. Sometimes it surely is, but war is always a last resort solution, representing not the continuation of diplomacy by other means, but instead a monumental failure. And because the chaos that accompanies that monumental failure is equally monumental, the outcome of a war -any war- can never be accurately predicted despite Posner's apparent self-assurance that it can. Except in one regard:

That innocent people will die horrible deaths approaches a confidence level of one.

In any event, by any criteria, except Bush's, nothing in the run-up to the Iraq war justified a preventive war by the US (and its allies).

Freder Frederson

Arguably France is the nation that has been most wedded to pure economic cost-benefit analyses in its Middle-East strategy

Sheesh, do you really believe the crap you write? Yes, France over the last ten years did have the closest economic ties to Iraq. But if you want the country that looks at the pure economic cost-benefit analysis in its Middle-East Strategy, we are it baby? We overthrew the first almost democratic country in the Middle East and installed a dictator because we thought it would be too friendly to the USSR (Iran). When the Shah got overthrown we supported Iraq in Saddam's war against Iran out of spite eventhough Iraq was closer to the Soviet Union than us and we knew how awful Saddam was. You admit that Saudi Arabia is a problem yet we are their biggest backers and we didn't say a word when they delayed their elections and announced women would not be able to vote (look for them to quietly cancel them completely with no complaint from us).

Do you really think that a "revolution from within" will result in more friendly governments in Iran or Syria? Be serious. Chances are we will try in foment one and it will be tainted by our influence and result in a fundamentalist backlash. The hardliners in Iran have gained power, not lost it, since 9/11 because they have got the country to rally around the flag against us and increased oil revenues have allowed them to buy off the fence sitters. We support corrupt dictatorships in Pakistan, Saudi Arabia, the Gulf States, Egypt, and Jordan. This administration has shown no real interest in pressuring them to change nor has it pressured Israel and the Palestinians to come to some kind of accomodation.


Uncertainty does not justify a bias in favor of inaction. Inaction is a decision with consequences, just as it action. Since human behavior is inherently uncertain, all social choices, even those classified as inaction, must be made in the face of uncertainty. This necessitates the assignment of probabilities that are themselves only uncertain estimates. There is no alternative. Therefore, Richard Posners methodology is inescapable. Of course, this method can be used to justify any action or inaction.

The typical argument in favor of the US invasion of Iraq includes the following:
Saddam Hussein was a genocidal dictator who had already slaughtered more than 1 million people and would probably kill more if left in power. He had probably already assisted terrorists acting against US interests and would probably do so in the future. Containment was not effective and would probably deteriorate over time. The defeat of Saddam Hussein would probably discourage other nation states from supporting terrorism in the future. The US could probably establish democracy in Iraq as it did in Germany, Japan, and South Korea and democracy in Iraq would probably encourage liberalization among Arab nations and thereby reduce support for terrorism.

Not all of these uncertain expectations need to be true to justify the US invasion of Iraq, but it is clear that the decision to invade can not be justified with certainty.

What about the decision not to invade? This would typically include the following:
The US is not responsible for Saddam Husseins genocide and should therefore give it only minor weighting in any decision, but the US would be fully responsible for all deaths that occur due to its invasion. Saddam Hussein might kill far fewer people in the future than he did in the past, in part due to containment. Containment of Saddam Hussein will probably work adequately far into the future. Invasion of Iraq will probably motivate more Islamists to become terrorists than would inaction. Overthrowing Saddam Hussein will probably not deter other nation states from supporting terrorism. The US is unlikely to ever succeed in establishing democracy in Iraq. Saddam Hussein probably never had significant ties with terrorists acting against the US and probably never will in the future if the US does not invade Iraq. The US can probably prevent future terrorists acts against the US or at least keep them to a cost less than that of war in Iraq.

Clearly, the decision not to invade Iraq is based only on probabilities, not certainties. Hence, there can be no certainty. We are forced to argue probabilities.

Steven Lance

I don't think Judge Posner omitted "the discounted value of these future defense expenditures" from his cost-benefit example. In the case of the United States, there is no such benefit. The only nation states that threaten the United States are already on the outside of international law (North Korea, Iran). There is no increase in the threat of attack from say Canada, as the first commenter so foolishly suggests.

In fact, the primary stabilizing force throughout history has not been any rule agaisnt pre-emptive attacks (which have been common forever) but rather the fear of destruction by a superior force. East and West Germany existed in relative peace not because of any international law, but because the United States and USSR assured the destruction of either, should it turn agressive.

In this context, I would argue that the United States, as the sole super-power, discouraged agression by rouge nations when it attacked Iraq (both times) and Afghanistan. A pre-emptive military policy serves the same goal as agressive police enforcement of minor violations, it cleans up the whole neighborhood. Our pull-out of Vietnam on the other hand, had the opposite effect and encouraged minor conflicts around the globe, as did the failure of the USSR to subdue Afghanistan.


"East and West Germany existed in relative peace not because of any international law, but because the United States and USSR assured the destruction of either, should it turn agressive."

That is a gross oversimplification of an exceedingly complicated situation, one in which MAD surely was an element, but which also included the utlility of institutions of international law and the deployment, after October '62, of state of the art communications technologies by world leaders.

If US "discouraged agresion [sic] by rogue nations," how come the world has Darfur? And what on earth is a rogue nation anyway?

Cato Renasci

Anonymous- your links don't work so I've no idea where you're referring me.
I've always been uncomfortable with claims that calculations of utility can be neat and part of a truly orderly continuum -- as I thought my post made clear. As economists or social choice theorists we use relatively simple models such as the 'utility calculation continuum' because we're convinced they're useful (i.e. generally good enough, not because we're convinced they're exhaustively accurate) and because they lend themselves to relatively straightforward explication. When we want to be significantly more precise in defining our functions, for example, the mathematical price of admission to the discussion shifts from the calculus one expects most undergraduates to understand (at least generally) to the sorts of advanced mathematics understood by few (a prominent mathematical economist once suggested to me in a conversation that there were less than 100 people in the world who were really capable of understanding and contributing to the literature, and half of them were mathematicians who couldn't care less).Nonetheless, I am not persuaded by your distinction between risk and ambiguity, nor am I convinced that modelling decisionmaking under uncertainty (risk) is inappropriate to model decisionmaking under ambiguity. You may have blogged on it, but I guess I'd need to see a more fully fleshed out argument, perhaps even the mathematics you have it mind (though, as I said before, I'm very rusty with serious mathematics).


Tristero writes:

'If US "discouraged agresion [sic] by rogue nations," how come the world has Darfur?'

Let's not play dumb now. Clearly he meant aggression against the United States. Is Darfur a part of the US? "Duh".

Rob W

Uncertainty does not justify a bias in favor of inaction.


Your analysis fails to account for the fact that greater uncertainty exists concerning the prediction of the threat as opposed to calculating the negative consequences to a state engaging in preventative war. Negative consequences to a state engaging in preventative war would be far easier to calculate because their effects would be much closer in time to the decision to go to war. A threat calculus must take into account a potential threat years into the future, making prediction much more difficult.

Since it is assumed that the calculation is being made to determine if a preventative war is to be launched now, the calculation of the negative consequences is far easier than the threat.

Thus the risk of inaction will always be easier to calculate and to mention the costs of inaction in the same breath as action does not to full justice to the problem.

The factor of uncertainty of threat demonstrates that the calculus will more often than not fall on the side of "angels fearing to tread" rather than "fools rushing in."

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