Posner forgets himself again

by Kieran Healy on December 21, 2005

A commenter in “our previous post”:https://crookedtimber.org/2005/12/21/posner-forgets-himself/ points to “this chat session”:http://www.washingtonpost.com/wp-dyn/content/discussion/2005/12/20/DI2005122001142.html with Posner, hosted by the _Washington Post_. Besides forgetting everything he ever learned about public choice theory, Posner also seems to have abandoned the cost-benefit methods which made him famous. He is now convinced that radical uncertainty is not amenable to probabilistic analysis:

*Question*: … Nothing in the Constitution does (or could) provide a guarantee of safety. I suspect that I am statistically much more at risk of being run over by a car than of being killed by a terrorist (even though I live within five miles of the White House). Should the government ban all automobiles to protect me?

*Richard Posner*: If your premise were correct, your conclusion would follow. But how do you know you’re at less risk of being killed by a terrorist than being run down by a car? The risk in the sense of probability of being killed by a nuclear bomb attack on Washington, a dirty-bomb attack, an attack using bioengineered smallpox virus, a sarin attack on the Washington Metro (do you ever take the metro?), etc., etc., cannot be quantified. That doesn’t mean it’s small. For all we know, it’s great. Better safe than sorry.

How far this all is from the confidence with which Posner “typically slaps probabilities on things”:https://crookedtimber.org/2004/12/06/posner-and-becker-comedy-gold in order to justify some policy. Here he is arguing about preventive war in 2004:

Should imminence be an absolute condition of going to war, and preventive war thus be deemed always and everywhere wrong? Analytically, the answer is no. A rational decision to go to war should be based on a comparison of the costs and benefits … Suppose there is a probability of .5 that the adversary will attack at some future time, when he has completed a military build up, that the attack will, if resisted with only the victim’s current strength, inflict a cost on the victim of 100, so that the expected cost of the attack is 50 (100 x .5), but that the expected cost can be reduced to 20 if the victim incurs additional defense costs of 15. Suppose further that at an additional cost of only 5, the victim can by a preventive strike today eliminate all possibility of the future attack. Since 5 is less than 35 (the sum of injury and defensive costs if the future enemy attack is not prevented), the preventive war is cost-justified.

I guess his epistemological position has changed a great deal in the meantime. Incidentally, about “forty two thousand people a year”:http://www-fars.nhtsa.dot.gov/ are killed in automobile accidents in the United States. Do the math yourself.



Sebastian Holsclaw 12.21.05 at 6:24 pm

I agree that I don’t like how Posner (or lots of prominent political figures) deals with statistics. At least 3 out of 4 people misuse them, you know.

But as for:

I guess his epistemological position has changed a great deal in the meantime. Incidentally, about forty two thousand people a year are killed in automobile accidents in the United States. Do the math yourself

That doesn’t prove anything. Automobiles are very useful things for most people in the US society. You have to weigh the cost in terms of accidents vs. the utility of having automobiles. Terrorist attacks attempting to kill 30,000 people while destroying the Twin Towers don’t have very much societal utility in the United States. A nuclear weapon ‘stolen’ from Iran and detonated in a US city doesn’t have much societal utility either.

The problem is that neither side of the security debate is much interested in thinking about tradeoffs. Some say that if we alter our current understanding on civil rights at all we have “let their terrorists win”. Others seem to suggest that almost anything that stops another terrorist attack is worth it. The whole question is one of trade-offs, and it would be better if we focused on that fact all the time.

Cars are useful. We trade off accidents against that utility. Terrorist attacks aren’t useful. (You might analyze people killed vs. number of cars used each day against people killed per attempted terrorist attack if you wanted a more useful number).

We might have very different risk assessments in protecting against terrorists than we do with cars. That isn’t crazy, though some of Posner’s proposed remedies might not make the tradeoff properly.


John Quiggin 12.21.05 at 6:43 pm

Sebastian, your point is better directed against Posner. He’s not arguing for a more comprehensive BC analysis than the one Kieran has sketched. Rather he’s claiming such a thing is impossible.

His final point “better safe than sorry” is just our old friend the precautionary principle. I have some sympathy for this, but until now Posner has not.

Finally, I had you pegged as something of a libertarian. Are you saying that personal liberty is less valuable than motor transport? If not, won’t consideration of the benefits side of the analysis strengthen the case against police state measures?


Sebastian Holsclaw 12.21.05 at 6:45 pm

To be extra clear, I think very few people who talk use arguments as if they were civil right’s absolutists or as if they were “no cost is too high to stop terrorism” absolutists are actually absolutist when it comes down to it. I’m not trying to raise straw men. Nevertheless, it feels like lots of people argue without firmly keeping in their mind the trade-off nature of such decisions. The “cars kill more people than terrorists” argument ignores the utility of cars that might allow us to trade off injuries and deaths. The “destroy terrorism everywhere” mindset ignores the cost of doing the things that involve destorying terrorism everywhere. We could probably all bring more to the discussions if we kept the positives and negatives of the trade offs more firmly in mind. (Which Kieran correctly notes at the beginning of his post but has abandoned (forgotten?) by the end). I don’t think that speaks poorly of Kieran. It rather shows how easy it is to lose the cost-benefit focus while making a point. (A problem I have all the time).


Sebastian Holsclaw 12.21.05 at 6:48 pm

BTW John and I cross-posted.

“Are you saying that personal liberty is less valuable than motor transport? If not, won’t consideration of the benefits side of the analysis strengthen the case against police state measures?”

I don’t think it can be analyzed at the level of abstraction. Motor transport adds quite a bit to personal liberty. Not getting your door busted down in erroneous terrorist crackdown does too. ‘Police State Measures’ come in different sizes and shapes. Are we talking about torturing people or wiretapping foreign conversations?


alex 12.21.05 at 7:04 pm

Sebastian, keep in mind that Posner says, about automobile accident rates, “If your premise were correct, your conclusion would follow.” It would have been entirely possible for Posner to say something different, i.e. consider the benefits from automobiles, etc etc, so that the premise (high likelihood of accidents) does not imply the conclusion (ban automobiles). So Kieran’s post engages Posner on his own terms.


Barry 12.21.05 at 7:15 pm

Sebastian, I believe that the point of the post was that Posner was quite willing to slap probabilities and cost/benefits on things like people getting killed – until it came to something which would cut against Bush’s power. Then, he wanted to throw that out, basically planting an arbitrarily high cost to a terrorist attack, to get the decision that he wanted.


Nick 12.21.05 at 7:25 pm

Automobiles are very useful things for most people in the US society. You have to weigh the cost in terms of accidents vs. the utility of having automobiles. Terrorist attacks attempting to kill 30,000 people while destroying the Twin Towers don’t have very much societal utility in the United States.

True but silly since just as one does not bother saying things like “Car crashes don’t have very much societal utility”, one doesn’t bother saying “Terrorist attacks don’t have very much societal utility.” Instead one says “Civil liberties have very much societal utility”.

Posner’s analysis actually seems much more bizarre than Kieran gives it credit for. He seems to think that the question of whether we should ban all automobiles depends not on the “weigh[ing of] the cost in terms of accidents vs. the utility of having automobiles” but rather on whether or not we can quantify the risk of terrorism.

Question: … I suspect that I am statistically much more at risk of being run over by a car than of being killed by a terrorist … Should the government ban all automobiles to protect me?

Richard Posner: If your premise were correct, your conclusion would follow.

If we could quantify the risk of terrorism and it turned out to be to lower than the risk of automobiles, he says, then we should ban all automobiles. As though the risk of terrorism, whatever its unknown value might be, is some kind of magical lower bound above which massive government intervention is always warranted.

One can only hope that Osama bin Laden will come out tomorrow and tell us that he plans to kill no more than 42,000 people per year so that Richard Posner can move onto that argument and leave this one in peace.


Pithlord 12.21.05 at 7:53 pm

Posner is just distinguishing, rather conventionally, between risk (where the probability of the bad event is known) and uncertainty (where it isn’t). He just wrote a book about what public policy should do about events that are cataclysmic in their impact and difficult to assess in their probability.

True, “better safe than sorry” sounds like a bad version of the precautionary principle. The obvious objection is that there is no “safe” choice, for civil liberties any more than for food. If we give the government more power, there are risks. If we don’t, there are risks.

Posner is notoriously uninterested in privacy, which he thinks is incoherent, so that might explain some of this.

Personally, my concern is less with the spying and more with the Administration claiming it has inherent power to ignore the law.


Thomas 12.21.05 at 8:01 pm

Posner on global warming: “Because of the enormous complexity of the forces that determine climate, and the historically unprecedented magnitude of human effects on the concentration of greenhouse gases, the possibility that continued growth in that concentration could precipitate—and within the near rather than the distant future—a sudden warming similar to that of the Younger Dryas cannot be excluded. Indeed, no probability, high or low, can be assigned to such a catastrophe. It may be prudent, therefore, to try to stimulate the rate at which economical substitutes for fossil fuels, and technology both for limiting the emission of carbon dioxide by those fuels when they are burned in internal-combustion engines or electrical generating plants, and for removing carbon dioxide from the atmosphere, are developed. This can be done, in part anyway, by stiff taxes on carbon dioxide emissions. Such taxes give the energy industries, along with business customers of them such as airlines and manufacturers of motor vehicles, a strong incentive to finance R&D designed to create economical clean substitutes for such fuels and devices to “trap” emissions at the source, before they enter the atmosphere. Given the technological predominance of the United States, it is important that these taxes be imposed on U.S. firms, which they would be if we ratified the Kyoto Protocol and by doing so became bound by it.”

I’m sure Kieran and John Q will have a field day with this.


Thomas 12.21.05 at 8:06 pm

I suppose they should comment on this one from Posner as well:

Good comments, and mostly supportive though some skeptical along the lines of climate models are complex, climate science is uncertain, the experts may be wrong. All true; but reading the skeptical literature, I am reminded of the debates in the 1960s over the effects of cigarette smoking on human health. The evidence for serious ill effects was already very strong, but there were skeptics, some financed by the tobacco industry, who said such things as: the evidence is statistical, the mechanism by which nicotine and tars cause changes in lung tissue, etc. is not well understood, and in short we can’t be certain that there are these effects—the implication being that we should do nothing. Similar points are made today, often by energy companies or persons in their pay, and similarly insinuating that, given uncertainty, we should do nothing.

That is a non sequitur. We rarely have the luxury of being able to act on certainties; you’d be a fool if, credibly informed that unless you had an operation to repair an aneurysm you had a 99 percent chance of dying within a week, you responded that you only act when you’re certain. In my last posting, I speculated that a 1 percent chance of criminal punishment might deter certain copyright violations, and I didn’t mean that only the irrational would be deterred.

What would be irrational would be to conclude, from the fact that a minority of scientists deride global warming fears, that we should ignore the problem. Indeed, if you look at their grounds for skepticism, you may become more alarmed about global warming rather than less so. Because what you will learn is that their skepticism is based mainly on the existence of profound uncertainties about climate, and those uncertainties cut both ways and by doing so imply added rather than diminished risk. For example, skeptics point out that in the earth’s prehistory there have been periods (one roughly 10,000 years ago) in which the concentration of carbon dioxide in the atmosphere spiked, even though cavemen didn’t drive SUVs. Yes, and if one of those non-human-induced spikes coincided with our human-induced spiking, we’ll be in real trouble.

I mentioned in passing, in the preceding posting, risk aversion. If you would rather pay $100 certain than run a 1 percent risk of a $9,999 loss, even though the expected cost of such a risk is only $99.99, then you’re risk averse (think of the $100 as an insurance premium). The greater the variance in possible outcomes, the more upset the risk averse are likely to be. The more uncertainty there is about climate, the greater the variance in possible consequences of increasing the atmospheric concentration of carbon dioxide (and of other greenhouse gases, such as methane, which is even more heat-retentive than carbon dioxide, and is being released into the atmosphere in increased quantity because of the melting of the Alaskan and Siberian permafrost—and you can see what a dangerous feedback effect is possible as more methane in the atmosphere raises surface temperatures which melts more permafrost releasing more methane…). So people who are risk averse, and that is most of us when we are facing potential disaster on the scale that global warming might inflict, will not be reassured by people who ground their global warming skepticism in nothing solider than a reminder that other things besides human activity affect climate; those other things seem as likely to exacerbate the effects of human activity as to offset them.


Kieran Healy 12.21.05 at 8:15 pm

Posner is just distinguishing, rather conventionally, between risk (where the probability of the bad event is known) and uncertainty (where it isn’t).

I’m well aware of this distinction, as (believe me) is John. It just seems that there are times when Posner is quite happy to assign definite probabilities to events and engage the C/B machinery, and other times when he takes them as radically uncertain — I’m just wondering whether it’s our state of knowledge that determines this choice for him, or some policy he’s already in favor of.


John Quiggin 12.21.05 at 8:44 pm

“Are we talking about torturing people or wiretapping foreign conversations?”

Both, presumably. The Administration is doing both and using the same arguments in each case.

This is one reason not to try and apply benefit-cost analysis on a case-by-case basis. Each breach of freedom (including past breaches under Clinton, Reagan, FDR and so on) prepares the ground for more.


Thomas 12.21.05 at 9:02 pm

I think it’s pretty clear what Posner’s methodology is. He assigns a very high cost to some bad events, including some kinds of terrorist attacks (e.g., bioterrorism, nuclear terrorism). For example, he has publicly talked about the possibility of a bioterror attack killing 100 million Americans, at a cost, he suggests, of $1 quadrillion. Needless to say, if one is risk averse–as Posner indicates he is (“better safe than sorry”)–almost any positive value on the probability side leads to positive steps to prevent such an attack. As Posner surely must concede, intuition likely is serving an important role in the assigning of probabilities. And, surely, intuitions aren’t free of bias. Which is likely the best explanation for Posner’s arguments for steps to prevent global warming and to protect the plan from asteroids. Everyone recognizes that these policy positions are popular among schmibertarian lawyers.


Barry 12.21.05 at 10:05 pm

BTW, slapping arbitrarily high costs to an event can skew the C-B analysis. How many biowarfare experts think that a 100 million death attack is at all credible?


Barbar 12.21.05 at 11:32 pm

Putting aside the grand unified theory of Posner, both of the quotes in Kieran’s original post are absurd. In the first, Posner seems to be saying that we should ban automobiles if the risk of terrorism is sufficiently low. In the second, Posner makes up a bunch of numbers to show that it is theoretically possible for a cost/benefit analysis to favor war against a non-imminent threat, which is a trivial point that actually requires no math.

Thomas, Posner cannot simply be saying that some events have arbitrarily high downside, because that dodges the question of *how much* we should pay to prevent terrorism, or global warming. Surely he is not saying that there is no bound to how much we should pay; you yourself just say that there should be some positive value if the probability is nonzero. But how helpful is that?

What interesting things are there to say about cost/benefit analyses?

1) You can attempt to actually measure costs and benefits of potential actions.
2) You can discuss how such analyses are affected by risk and uncertainty.
3) You can weigh a cost/benefit analysis with a “values” analysis, probably by bringing some game theory into the discussion, as well as ethical theory.

In the Posner quotes that appear in this thread, we have a little bit of #2 and that’s it.


joel turnipseed 12.21.05 at 11:33 pm

Funny, I just had dinner w/little Bro’ tonight-just home from his own Iraq war & was thinking of this very thing as I listened to how his talk had changed…

The car analogy (and its problems) is good. I think the thing about c/b w/r/t “war on terror” is: someone else is, more or less, bearing the cost in most people’s analysis (such as it exists). So, if you asked me, “Would you sacrifice X’s chance of survival to increase your own (and many Y-percent of your friends/relatives) by Z percent, would you?” I might very well answer, “Yes.” Especially if that someone else were, say, an Iraqi. The math, anyway, is heavily on “my” side… especially given how easy it is to underestimate how tenuous are our connections to other people–or undervalue them (as history & psychologists have shown repeatedly).

Now, I wouldn’t, because I find the effects of militarism/national security state/unconscionable casualties/blowback too terrible to justify our current war in Iraq–but it’s not hard for me to see how people could make this analysis, and if you can’t, then you really don’t understand much about the way humans think–or why we’re so susceptible to the criminal government with which we’re currently stuck.

The question, then, becomes, “How to get people to think beyond themselves/more deeply about long-term effects to themselves”–honestly? That may just be impossible, as witness the horrible, bloody, 20th century.


ogmb 12.22.05 at 12:25 am

I don’t think the two quotes are linked in the way Kieran claims. The 2005 quote is about establishing an empirical relationship, which Posner justifiably refuses to do. We have historical precedent on car accidents, we don’t have them on dirty bombs. The 2004 quote is a classroom example with clearly made-up numbers to establish the possibility of an outcome. Clearly Posner could make up probabilities for the dirty bomb scenario, but the number would be in no meaningful way comparable to the car accident number, which we can derive very precisely from a long line of observations.


Eli Rabett 12.22.05 at 12:28 am

C’mon, it is perfectly clear what Posner is doing and has always done. He starts with his preferred conclusion and picks his numbers to fit. Assigning him any credibility whatsoever is foolish. It is only that this time he jumped the shark.


joel turnipseed 12.22.05 at 12:42 am

On additional consideration: the “car accidents” model of utility is actually a tougher one for anti-war people to uphold than I thought on initial posting. If you looked at mortality statistics for cohort in Iraq (US) and their comparable US population, you wouldn’t find a very large increase in mortality/injury rates (my grandfather, an economist & pioneer in forensic economics, pointed this out to me, as well as several psychiatrists working in PTSD) as a rate (it works out to about a 1.5 to 2.0 increased rate per 100,000). It’s about the equivalent of asking young people to become truck drivers or nurses (two most dangerous jobs in U.S.) rather than accountants or teachers. For that matter, given the cohort in question, it’s not clear that it’s not closer to a 1:1 ratio when taking likely civilian occupation/sociological factors into account.

That’s not to say that there aren’t other risks to fighting wars… just to say: those risks are moral/intellectual/political rather than physical. And thus: you get to some of the standard objections to utilitarian theory, generally–and on these (and thus, right) the anti-war opinion must be upheld.

I am happy to uphold an anit-war opinion–but if a utilitarian disagreed with me, it would be on the basis of the axioms of their moral philosophy, not their reasoning (as, I think, Posner’s defenders on this thread have amplified).


Thomas 12.22.05 at 12:44 am

Barbar, I didn’t mean to suggest that Posner was using arbitrarily high numbers, just that the focus was on extreme cases. That is, in considering the threat of a terrorist attack, he doesn’t focus much on the possibility of, say, a repeat of the anthrax attacks of 2001, but instead focuses on scenarios killing millions.

As I understand it, Posner, when addressing these issues in more detail (that is, in his book on the subject and not in a real-time online chat), does try to focus on actual costs and benefits. (I’ll quote a sample of that kind from his blog, at the bottom.) He also, as I understand it, supplies some reasons for thinking that people systematically underestimate the risks posed by low probability events.

Here’s another bit from his blog:

The Indian Ocean tsunami illustrates a type of disaster to which policymakers pay too little attention—a disaster that has a very low or unknown probability of occurring, but that if it does occur creates enormous losses. Great as the death toll, physical and emotional suffering of survivors, and property damage caused by the recent tsunami are, even greater losses could be inflicted by other disasters of low (but not negligible) or unknown probability. The asteroid that exploded above Siberia in 1908 with the force of a hydrogen bomb might have killed millions of people had it exploded above a major city. Yet that asteroid was only about 200 feet in diameter, and a much larger one (among the thousands of dangerously large asteroids in orbits that intersect the earth’s orbit) could strike the earth and cause the total extinction of the human race through a combination of shock waves, fire, tsunamis, and blockage of sunlight, wherever it struck. Other catastrophic risks include, besides earthquakes such as the one that caused the recent tsunami, natural epidemics (the 1918–1919 Spanish influenza epidemic killed between 20 and 40 million people), nuclear or biological attacks by terrorists, certain types of lab accident, and abrupt global warming. The probability of catastrophes resulting, whether or not intentionally, from human activity appears to be increasing because of the rapidity and direction of technological advances.

The fact that a catastrophe is very unlikely to occur is not a rational justification for ignoring the risk of its occurrence. Suppose that a tsunami as destructive as the Indian Ocean one occurs on average once a century and kills 150,000 people. That is an average of 1,500 deaths per year. Even without attempting a sophisticated estimate of the value of life to the people exposed to the risk, one can say with some confidence that if an annual death toll of 1,500 could be substantially reduced at moderate cost, the investment would be worthwhile. A combination of educating the residents of low-lying coastal areas about the warning signs of a tsunami (tremors and a sudden recession in the ocean), establishing a warning system involving emergency broadcasts, telephoned warnings, and air-raid-type sirens, and improving emergency response systems, would have saved many of the people killed by the Indian Ocean tsunami, probably at a total cost below any reasonable estimate of the average losses that can be expected from tsunamis. Relocating people away from coasts would be even more efficacious, but except in the most vulnerable areas or in areas in which residential or commercial uses have only marginal value, the costs would probably exceed the benefits. For annual costs of protection must be matched with annual, not total, expected costs of tsunamis.

In my book Catastrophe: Risk and Response (Oxford University Press 2004), I try to be more precise about how one might determine the costs of catastrophes. There is now a substantial economic literature inferring the value of life from the costs people are willing to incur to avoid small risks of death; if from behavior toward risk one infers that a person would pay $70 to avoid a 1 in 100,000 risk of death, his value of life would be estimated at $7 million ($70/.00001), which is in fact the median estimate of the value of life of an American. Because value of life is positively correlated with income, this figure cannot be used to estimate the value of life of most of the people killed by the Indian Ocean tsunami. A further complication is that the studies may not be robust with respect to risks of death much smaller than the 1 in 10,000 to 1 in 100,000 range of most of the studies; we do not know what the risk of death from a tsunami was to the people killed. Additional complications come from the fact that undoubtedly more than 150,000 people have died or will die—and the total may never be known—and that there is vast suffering and property damage that must also be quantified, as well as estimates needed of just how effective precautionary measures of various scope and expense would have been. The risks of smaller but also still destructive tsunamis that such measures might protect against must also be factored in; nor am I confident about my “once a century” risk estimate. Nevertheless, it seems apparent that the total cost figure of the recent tsunami will come in at an amount great enough to indicate that there were indeed precautionary measures to take that would have been cost-justified.

Why, then, weren’t such measures taken in anticipation of a tsunami on the scale that occurred? Tsunamis are a common consequence of earthquakes, which themselves are common; and tsunamis can have other causes besides earthquakes—a major asteroid strike in an ocean would create a tsunami that would dwarf the Indian Ocean one.

There are a number of reasons for such neglect. First, although a once-in-a-century event is as likely to occur at the beginning of the century as at any other time, it is much less likely to occur in the first decade of the century than later. Politicians with limited terms of office and thus foreshortened political horizons are likely to discount low-risk disaster possibilities, since the risk of damage to their careers from failing to take precautionary measures is truncated. Second, to the extent that effective precautions require governmental action, the fact that government is a centralized system of control makes it difficult for officials to respond to the full spectrum of possible risks against which cost-justified measures might be taken. The officials, given the variety of matters to which they must attend, are likely to have a high threshold of attention below which risks are simply ignored. Third, where risks are regional or global rather than local, many national governments, especially in the poorer and smaller countries, may drag their heels in the hope of taking a free ride on the larger and richer countries. Knowing this, the latter countries may be reluctant to take precautionary measures and by doing so reward and thus encourage free riding. Fourth, countries are poor often because of weak, inefficient, or corrupt government, characteristics that may disable poor nations from taking cost-justified precautions. Fifth, people have difficulty thinking in terms of probabilities, especially very low probabilities, which they tend therefore to write off. This weakens political support for incurring the costs of taking precautionary measures against low-probability disasters.

The operation of some of these factors is illustrated by the refusal of the Pacific nations, which do have a tsunami warning system, to extend their system to the Indian Ocean prior to the recent catastrophe. Tsunamis are more common in the Pacific, and most of the Pacific nations do not abut on the Indian Ocean, but even if the risk of an Indian Ocean tsunami was only a tenth of that of a Pacific Ocean tsunami (a figure I have seen in a newspaper article), it was still worth taking precautions against; but there is a tendency to write down slight risks to zero.

An even more dramatic example of neglect of low-probability/high-cost risks concerns the asteroid menace, which is analytically similar to the menace of tsunamis. NASA, with an annual budget of more than $10 billion, spends only $4 million a year on mapping dangerously close large asteroids, and at that rate may not complete the task for another decade, even though such mapping is the key to an asteroid defense because it may give us years of warning. Deflecting an asteroid from its orbit when it is still millions of miles from the earth is a feasible undertaking. In both cases, slight risks of terrible disasters are largely ignored essentially for political reasons.

In part because tsunamis are one of the risks of an asteroid collision, the Indian Ocean disaster has stimulated new intereset in asteroid defense. This is welcome. The fact that a disaster of a particular type has not occurred recently or even within human memory (or even ever) is a bad reason to ignore it. The risk may be slight, but if the consequences should it materialize are great enough, the expected cost of disaster may be sufficient to warrant defensive measures.


Barbar 12.22.05 at 12:51 am

ogmb, if the cost of an action is less than the benefit of the action, then cost-benefit analysis recommends that you do that action.

No kidding. Of coures this extends to literally any kind of action, including multilating your genitals, eating babies, raping old people, and attacking a non-imminent threat. What exactly is the point of the “classroom example” with the made-up numbers?

Also, you don’t adequately explain Posner’s 2005 quote. The questioner is obviously suggesting that the risk of terrorism is being overstated; the response — that the risk of terrorism cannot be precisely quantified, so therefore caution dictates that it can’t be overstated either — is incoherent.


Daniel 12.22.05 at 12:59 am

Are we talking about torturing people or wiretapping foreign conversations?

As I’ve mentioned before, give me the second with no checks and balances and with a little bit of ingenuity I’ll deliver you the first.


joel turnipseed 12.22.05 at 1:15 am

Barbar: actually, I don’t think the “risk of terrorism” is overstated, especially given the “other guys dying” factor + actual increase in expected mortality. Let’s say you think there’s a 1/1000 chance, “War on Terror” abandoned, of a terrorist attacking with a casualty rate of 5000 deaths. Let’s say you–generously–consider other lives worth 2% of your own & you were 97% sure you weren’t going to be fighting said war. I think Kieran’s just arguing that Posner’s switching his basis of moral reasoning… for his own convenience.

But does he have to? If Thomas’ numbers are right (and they’re close to what my grandfather would put it, on average), then saving 5000 lives is worth 3.5 Trillion USD. Let’s say the increase over expectation is at its highest, or 2x, that means that, after three years, we could expect 1,250 additional lives lost than w/o War on Terror. Let’s subract their contributions from our sum (gruesome, I know–but we’re utilitarians here, for argument’s sake). We still have 2.6 trillion to spend… now, to discount based on probabilities. 1/1000th event leaves us at 2.6 billion in expenditure… 2% discount rate of death, however, puts us up to 100 billion and additional calculation for your personal risk of having to fight puts us up to about 97 billion.

You’re off by a 100 billion or so, as a utilitarian, but that’s easy to make up with a few adjustments–which is to say, on utilitarian calculus, the “War on Terror” isn’t insane. It’s insane in lots of other ways… but it’s at least arguable on this model of moral reasoning (along certain vectors, anyway–e.g., you don’t believe the war to be increasing the likelihood of future, successful, attacks).

The problem, of course, lies with utilitarian moral reasoning–and, more importantly, with the lack of Bush administration imagination on any standard of reasoning w/r/t this war. Just because something can be argued successfully w/in certain constraints doesn’t make it true (or right). I always think, in these cases, of Russell’s wonderful rejoinder to Fr. Coppleston in their debate on the existence of God, upon Coppleston’s putting of Pascal’s wager to Russell: “What if,” replied Russell, “I believed in a God who would damn me to hell for accepting his existence on a bet?”


ogmb 12.22.05 at 1:20 am

if the cost of an action is less than the benefit of the action, then cost-benefit analysis recommends that you do that action.

I’m not talking about the cost benefit analysis, I’m talking about Kieran’s setup of “here he uses probabilities, here he doesn’t”. Posner’s arguments are crap in both quotes, but that doesn’t make Kieran’s objection valid.


Geoff R 12.22.05 at 1:55 am

I like Posner mostly but sometimes his arguments are lazy and partisan, the scenarios of constitutional apocalypse in Breaking the Deadlock if the Florida ballot had not been resolved in time are a good example. This looks like a similar example.


a 12.22.05 at 3:32 am

Is it possible that Posner just made a mistake in the chat session? I presume it was in real-time and he had to answer on the go, so maybe he just took the question on its terms and replied accordingly. If people were judged by their conversation, then I doubt very many would turn out to be consistent. On the other hand, if Posner has made a similar point in any of his writings, then he would seem to be fair game.


Daniel 12.22.05 at 7:12 am

If Thomas’ numbers are right (and they’re close to what my grandfather would put it, on average), then saving 5000 lives is worth 3.5 Trillion USD.

? order of magnitude? 5000 x 7,000,000 = 35 billion. (So far in Iraq alone the USA has spent $225bn)


Barry 12.22.05 at 7:39 am

a, Posner was undoubtedly prepped and ready; the questions probably were screened, and not answered in true real time (i.e., q#1 blocked, q2 delayed while q3 was anwered, etc.). Also, as has been pointed out, he’s played C-B games quite often.

Geoff, the word that seems to fit is ‘consequentialist’, I believe.


Barry 12.22.05 at 8:47 am

Eli Rabett: “C’mon, it is perfectly clear what Posner is doing and has always done. He starts with his preferred conclusion and picks his numbers to fit. Assigning him any credibility whatsoever is foolish. It is only that this time he jumped the shark.”

IMHO, it’s just another case of ‘right-wing libertarianism’ being shown to be a fundamental contradiction.


joel turnipseed 12.22.05 at 11:36 am

well, daniel a) I was extremely tired… and b) I didn’t support the war anyway–still don’t, but it looks like consequentialists have even less leg to stand on than even their best devil’s advocate could hope for (unless they think we’re going to lose ~5M in an attack).


JR 12.22.05 at 12:01 pm

I suspect that Posner has a mild case of Asperger’s. He’s brilliant but limited, and he applies a very narrow set of simple economic principles to all sorts of unrelated problems in a blinkered and repetitive way. He is abnormally blind to ordinary human emotions and motivations. For example, he has argued seriously in favor of the right of women to sell their infant children at market prices. His fascination with repetitive simple arithmetic calculations is also indicative.

And here is a description of him from a recent New Yorker profile:

Posner prefers to avoid social life. “People don’t say interesting things,” he says… When you’re just talking with your friends about trivia, what’s the point?”

So, whether or not he is clinically an Asperger’s sufferer, he is not an ordinary person with a normal social life. It’s not surprising that he places no value on freedom from government surveillance. He doesn’t understand the concept of personal privacy.


Phaedrus 12.22.05 at 3:25 pm

Posner on the Precautionary Principle:

“The ‘precautionary principle’ (‘better safe than sorry’) popular in Europe is not a useful alternative to cost-benefit analysis, if only because of its sponginess.”

Unless following it gives Bush kinglike power, then I guess it’s ok.


Pithlord 12.22.05 at 6:15 pm

Sure, Posner’s a bit weird, but sometimes it gives him an interesting perspective.

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