Category Archive: Nuclear Weapons

On the Moral and Intellectual Bankruptcy of Risk Analysis: Garbage In, Garbage Out

Don Howard

For decades, risk analysis has been the main tool guiding policy in many domains, from environment and public health to workplace and transportation safety, and even to nuclear weapons. One estimates the costs and benefits from various courses of action and their conceivable outcomes, this typically in the form of human suffering and well-being, though other goods, like tactical or strategic advantage, might dominate in some contexts. One also estimates the likelihoods of those outcomes. One multiplies probability times cost or benefit and then sums over all outcomes to produce an expected utility for each course of action. The course of action that maximizes benefit and minimizes harm is recommended. In its most general form, we call this “cost-benefit analysis.” We call it “risk analysis” when our concern is mainly with the down-side consequences, such as the risk of a core meltdown at a nuclear power facility.

I have long been uneasy about the pseudo-rationalism of such analyses. An elaborate formal apparatus conveys the impression of rigor and theoretical sophistication, whereas the widely varying conclusions – one can “justify” almost any policy one chooses – suggest a high degree of subjectivity, if not outright, agenda-driven bias. But my recent entanglement in the debate about the risks and benefits of gain-of-function (GOF) experiments involving pathogens with pandemic potential (PPP) moves me to think and say more about why I am troubled by the risk analysis paradigm (Casadevall, Howard, Imperiale 2014).

The H1N1 Influenza Virus

The H1N1 Influenza Virus

The essential point is suggested by my subtitle: “Garbage In, Garbage Out.” Let’s think about each piece of a cost-benefit analysis in turn. Start with cost and benefit in the form of human suffering and well-being. The question is: “How does one measure pain and pleasure?” Is a full belly more pleasurable than warmth on a cold winter’s night? Is chronic pain worse than fear of torture? There are no objective hedonic and lupenic metrics. And whose pain or pleasure counts for more? Does the well-being of my immediate community or nation trump that of other peoples? Does the suffering of the living count more heavily than the suffering of future generations? Most would say that the unborn get some kind of vote. But, then, how can we estimate the numbers of affected individuals even just twenty years from now, let alone fifty, or one hundred years in the future. And if we include the welfare of too many generations, then our own, contemporary concerns disappear in the calculation.

Next, think about cataloging possible outcomes. Some consequences of our actions are obvious. Punch someone in anger and you are likely to cause pain and injury both to your victim and yourself. We could not function as moral agents were there not some predictability in nature, including human nature and society. But the obvious and near term consequences form a subset of measure zero within the set of all possible consequences of our actions. How can we even begin to guess the distant and long-term consequences of our actions? Forget chaos theory and the butterfly effect, though those are real worries. Who could have predicted in 1905, for example, that Einstein’s discovery that E = mc2 contained within it the potential for annihilating all higher organic life on earth? Who could have foreseen in the 1930s that the discovery of penicillin, while saving millions of lives in the near term, carried with it the threat of producing super-bacteria, resistant to all standard antibiotics, risking many more deaths than penicillin, itself, ever prevented? A risk analysis is only as good as one’s catalog of possible outcomes, and history teaches us that we do a very poor job of anticipating many of the most important.

Then think about estimating the probabilities of outcomes. Some of these estimates, such as estimating the probability of injury or death from driving a car five miles on a sunny day with light traffic, are robust because they are data driven. We have lots of data on accident rates with passenger vehicles. But when we turn to the exceptional and the unusual, there is little or no data to guide us, precisely because the events in question are so rare. We cannot even estimate reliably the risk of injury accidents from transporting oil by rail, because transporting oil by rail used to be uncommon, but now it is very common, and the scant evidence from past experience does not scale in any clear-cut way for the new oil transportation economy. Would pipeline transportation be better or worse? Who knows? When real data are lacking, one tries reasoning by analogy to other, relevantly similar practices. But who can define “relevantly similar”?

It is especially when one comes to extremely rare events, such as a global pandemic, that the whole business of making probability estimates collapses in confusion and disarray. By definition, there is no data on which to base estimates of the probabilities of one-of-a-kind events. Doing it by theory, instead of basing the estimate on data, is a non-starter, for in a vacuum of data there is also a vacuum of theory, theories requiring data for their validation. We are left with nothing but blind guessing.

Put the pieces of the calculation back together again. There are no objective ways of measuring human suffering and well-being. We cannot survey all of the possible outcomes of our actions. Our probability estimates are, in the really important cases, pure fiction. The result is that one can easily manipulate all three factors – measures of pain and pleasure, outcome catalogues, and probability estimates – to produce any result one wishes.

And therein lies both the moral and the intellectual bankruptcy of risk and cost-benefit analysis.

But it’s worse than that. It’s not just that such analyses can be manipulated to serve any end. There is also the problem of deliberate deception. The formal apparatus of risk and cost-benefit analysis – all those graphs and tables and numbers and formulas – creates a pretense of scientific rigor where there is none. Too often that is the point, to use the facade of mathematical precision in order to quash dissent and silence the skeptic.

Back to rare and catastrophic events, like a possible global pandemic produced by a GOF/PPP experiment gone awry. What number to assign to the suffering? However low one’s probability estimate – and, yes, the chances of such a pandemic are low – the catastrophic character of a pandemic gets a suffering score that sends the final risk estimate off the charts. But wait a minute. Didn’t we just say that we cannot anticipate all of the consequences of our actions? Isn’t it possible that any course of action, any innovation, any discovery could lead to a yet unforeseen catastrophe? Unlikely perhaps, but that doesn’t matter, because the consequences would be so dire as to overwhelm even the lowest of probability estimates. Best not to do anything. Which is, of course, an absurd conclusion.

This “apocalypse fallacy,” the invocation of possible catastrophic consequences that overwhelm the cost-benefit calculation, is an all-too-common trope in policy debates. Should nuclear weapons have been eliminated immediately upon the discovery that a “nuclear winter” was possible? There are good arguments for what’s now termed the “nuclear zero” option, but this is not one of them. Should the remote possibility of creating a mini-black hole that would swallow the earth have stopped the search for the Higgs boson at CERN? Well, sure, do some more calculations and theoretical modeling to fix limits on the probability, but don’t stop just because the probability remains finite.

So when the pundits tell you not to invest in new nuclear power generation technologies as the surest and quickest route to a green energy economy because there is a chance of a super-Fukushima nightmare, ignore them. They literally don’t know what they’re talking about. When a do-gooder urges the immediate, widespread use of an Ebola vaccine that has not undergone clinical trials, arguing that the chance of saving thousands, perhaps even millions of lives, outweighs any imaginable untoward consequences, ignore him. He literally does not know what he’s talking about. Does this mean that we should rush into nuclear power generation or that we should refuse the cry for an Ebola vaccine from Africa? Of course not, in both cases. What it means is that we should choose to do or not do those things for good reasons, not bad ones. And risk or cost-benefit arguments, especially in the case of rare eventualities, are always bad arguments.

It would be wrong to conclude from what I’ve just argued that I’m counseling our throwing caution to the wind as we do whatever we damned well please. No. The humble, prudential advice is still good, the advice that one think before acting, that one consider the possible consequences of one’s actions, and that one weigh the odds as best one can. It’s just that one must be aware and wary of the agenda-driven abuse of such moral reflection in the pseudo-rational form of risk and cost-benefit analysis.

That said, there is even still value in the intellectual regimen of risk and cost-benefit analysis, at least in the form of the obligation entailed by that regimen to be as thorough and as objective as one can in assaying the consequences of one’s actions, even if the exercise cannot be reduced to an algorithm. But that is just another way of saying that, to the moral virtue of prudence must be added the intellectual virtues (which are also moral virtues) of honesty and perseverance.


Sincere thanks to Arturo Casadevall and Michael Imperiale for conversations that sharpened and enriched my thinking about this issue.


Arturo Casadevall, Don Howard, and Michael J. Imperiale. 2014. “An Epistemological Perspective on the Value of Gain-of-Function Experiments Involving Pathogens with Pandemic Potential,” mBio. 5(5): . doi:10.1128/mBio.01875-14. (

Nuclear Options: What Is Not in the Interim Agreement with Iran

Don Howard

No one wants war with Iran over its nuclear ambitions. But the euphoria over the EU3+3 interim agreement with Iran, as well as many of the political attacks on the agreement, obscure core technical issues that should be fundamental to any assessment of what has really been achieved. There is no denying that much has been gained by way of Iran’s agreeing temporarily to cease uranium enrichment beyond the 5% level necessary for energy production and its agreeing to on-site inspections at its Fordow and Natanz facilities. But important questions remain about what is not included in the interim agreement. Here are four issues that should be more prominent in the debate:

1. The Interim Agreement Mandates No Reduction in Iran’s Capability for Uranium Enrichment. Iran agrees to cease uranium enrichment beyond the 5% level necessary for energy production and not to expand or enhance its uranium enrichment capabilities, for the duration of the interim agreement. Moreover, Iran agrees to dilute half of its 20%-enriched uranium hexaflouride (UF6) to a 5% level and to convert the remaining half to uranium oxide (UO2) for use in making fuel for its Terhran research reactor. But Iran has not agreed to any permanent reduction of its capability for uranium enrichment, a capability that significantly exceeds what is necessary for energy production. It is hoped that a yet-to-be-negotiated, long-term agreement will include a reduction in that capability. But the interim agreement requires no such reduction. At any moment, Iran could resume enrichment to bomb-grade levels. Moreover, the UF6 that is to be converted to UO2 can be reconverted to UF6 and then further enriched.

Arak Heavy Water Reactor

Arak Heavy Water Reactor

2. The Interim Agreement Requires No Inspections at the Arak (IR-40) Heavy Water Reactor. As explained in a helpful recent article by Jeremy Bernstein, the Arak reactor is central to any evaluation of Iran’s nuclear ambitions. It is not designed as a reactor for power generation. Though Iran says that the reactor will be used to produce medical isotopes, its most plausible purpose is to be a breeder reactor for the production of plutonium, which is the other standard fuel for atomic weapons that rely upon the process of nuclear fission (as with the North Korean bomb). It was Iran’s refusal to allow on-site inspections at the Arak reactor that stalled the talks a couple of weeks ago when France demanded more access to Arak. The new interim agreement does require Iran to provide to the International Atomic Energy Agency (IAEA) an updated “Design Information Questionnaire” regarding the Arak reactor, it stipulates that there will be no “further advances of [Iran’s] activities at Arak, it obligates Iran to take “steps to agree with the IAEA on conclusion of the Safeguards Approach for the reactor at Arak” (whatever that means), and Iran agrees to do no reprocessing of spent fuel (the main purpose of which would be to extract plutonium) and not to construct reprocessing facilities. But the interim agreement does not obligate Iran to allow on-site inspections at Arak. Inspections are stipulated for the Fordow and Natanz uranium enrichment facilities, but not at Arak. Iran’s intransigence on this point should give us pause as we try to determine the real purpose of that reactor. If plutonium production is the goal, then our obsession with Iran’s uranium enrichment capability could be distracting us from a more serious threat. A quick route to an Iranian atomic bomb could well be via plutonium produced at Arak. And, at present, Iran has agreed to no degradation of this potential plutonium production capability.

3. The Interim Agreement Does Not Address the Question of Weapons Delivery Systems. Iran is a technically sophisticated nation that has made impressive advances in missile technology in recent years. Much of this missile technology was borrowed from earlier Russian and Korean models. But the new, solid-fuel, Sejil-2 rocket, which was first tested five years ago, is an original Iranian design. It has an impressive, 2,000-km range with a 750 kg payload capacity and anti-radar coatings. The Sejil-2 could put a nuclear warhead on a target as far away as Cairo, Athens, or Kiev. Moreover, Iran has been making gains in its guidance technology.

That we should be paying attention to Iranian weapons delivery capabilities was made clear when, two days after the announcement of the interim agreement, Brigadier General Hossein Salami, the Lieutenant Commander of the Iranian Revolutionary Guard Corps IRGC), announced that Iran’s indigenous ballistic missile capability had recently achieved a “near zero” margin of error in targeting accuracy.

That it was General Salami who made the announcement about advances in Iranian ballistic missile technology reminds us of a political, not technical, issue that has also received insufficient attention in the public debate about the interim agreement. The question is, “Who is really in control?” The interim agreement was negotiated by Iranian Foreign Minister Mohammed Javad Zarif on behalf of the government of President Hassan Rouhani. But the Revolutionary Guard functions as almost a shadow government, with considerable independent authority. And much of the most impressive Iranian ballistic missile research and development has been conducted in facilities under IRGC control, such as the IRGC missile base at Bid Kaneh, where a mysterious explosion during a missile test in November 2011 killed General Hassan Tehrani Moqaddam, who was the head of the IRGC’s “Arms and Military Equipment Self-Sufficiency Program.”

4. The Interim Agreement Does Not Address Aspects of Nuclear Weapons Technology Aside from the Production of Fissile Materials. Nothing in the interim agreement restricts Iran’s ability to continue developing other technologies essential to nuclear weapons production, such as timing circuitry, detonators, and refined conventional explosives techniques involved in the assembly of a critical mass of fissile material. It is perhaps not well and widely enough understood that some of the bigger technical challenges for a nation seeking nuclear weapons lie not in the production of fissile material but in areas such as these. Consider the basic design of a plutonium bomb of the kind dropped on Nagasaki. A critical mass of plutonium is achieved by compressing the plutonium with a spherical blast wave from spherical shell of conventional explosives. The precise shaping of those conventional explosive charges and their precise, simultaneous detonation are among the most difficult technical challenges in bomb design and manufacture. By contrast, while enriching uranium and breeding plutonium require a major technical infrastructure, the physical, chemical, and engineering processes involved are widely understood and, in principle, not all that difficult to achieve. But the interim agreement places no obstacles in the way of research and development on these other aspects of nuclear weapons design. Iran is free to pursue such research as vigorously as it will and to produce a fully functional nuclear weapon awaiting only the insertion of the fissile material.

An assessment of what has been achieved with the interim agreement depends crucially upon a prior assessment of Iran’s goals with respect to nuclear weapons capability. If Iran’s aim had been to produce nuclear weapons as soon as possible, then the interim agreement at least slows down progress toward that goal. But another view is that Iran’s aim all along has been to develop the basic technical infrastructure for the rapid production of bomb-grade fissile material for use if and when it chooses. If that is Iran’s aim, then the interim agreement achieves much less by way of delaying progress to the goal.

We have to wait and see how the interim agreement works. But the celebration of seeming progress on the diplomatic front must be tempered by a clear understanding of the technical issues that are not addressed in the interim agreement, issues that must be the focus of any, longer term, follow-on agreement. Should there be no progress on enrichment capabilities, the Arak reactor, delivery systems, and the fundamentals of bomb design, then options other than diplomacy might have to be explored, starting with the re-imposition of sanctions.