One of the paradoxes of real-life decision-making discovered by Daniel Kahneman and the late Amos Tversky is that, while normative economic rationality seems to imply risk-aversion, people confronted with real decisions, though risk-averse when it comes to gains, act as if they are risk-seeking when it comes to losses. That is, they sometimes refuse to accept a smaller, certain loss if the alternative is a larger loss that arrives only with some probability, even when the small, certain loss has a smaller expected value than the gamble.
The famous case here [Tversky, A., & Kahneman, D. The framing of decisions and the psychology of choice. Science, 1981, 211, 453-458] involves asking groups of experts to decide how to treat a hypothetical epidemic in an isolated population of a disease that is inevitably fatal. In groups given the choice between a treatment approach certain to save one-third of the population and a treatment approach with one chance in three of saving everyone, most experts prefer to be sure of saving one-third. But in other groups given the choice between a policy that will kill two-thirds of the population for sure and one that has a two-thirds chance of killing everyone, they take the risk approach. Of course, the two choices are identical except for the phrasing (what Kahneman and Tversky called “framing.”)
[IRRELEVANT FOOTNOTE: I’m convinced that, in the (implausible) hypothetical given, the right thing to do is to gamble, however you frame it, because if two-thirds of the population dies the other third will be wracked with survivor guilt. Thus given the choice between a one-third chance of being alive after a horrible epidemic and a one-third chance of being alive with no such epidemic, I’d choose the latter, and that’s the choice that the decision-maker has to make on behalf of the population. But that’s beside the point of the K-T experiment, which could equally well involve a scattered rather than a concentrated group of potential victims.]
What makes me think of this is a conversation I had today with a very smart fellow: a hard-science Ph.D. with high-level government experience, now running a well-known, certified Good Guy research-and-advocacy group. He knew about as much about the smallpox question as I do, which is to say more than the average newspaper reader but not very much. His immediate take was that it was a hard question, because, as he put it, “You’re weighing real lives that would be lost to vaccination against hypothetical lives that would be saved in case of an attack.”
That seems to me like the wrong way to think about the problem: it’s about like saying that your fire-insurance premium is “real money” but the loss you would suffer if your house burned down uninsured is merely hypothetical. But it also seems as if it might be a very common way to think about it, and something likely to bias decision-makers against mass vaccination.
Now let me repeat that my conviction that we ought to go ahead with mass vaccination, while strong, is self-consciously ill-informed, and wouldn’t be very hard to change with some additional evidence or analysis. I just had a long email from a real expert, who tells me flatly that I’m wrong and that mass vaccination now would be a bad idea. (I will post it if the author gives permission: the key concepts are the opportunity cost of smallpox vaccination in a world of limited public health capacity and multiple threats [e.g., anthrax]; the fragility of public trust in public health recommendations, and thus the need for a lengthy process of public education before children start dying; the opportunity cost of shooting our whole vaccine supply and having none available to deal with actual outbreaks, here or elsewhere, if they happen; the promise of a lower-side-effect-profile vaccine within a couple of years; and some strategic and diplomatic considerations.)
What worries me is that, in the wake of the Swine Flu fiasco and in light of some of the Kantianism-on-steroids that passes for bioethics, we may be suffering from a massive failure of collective nerve that would make it impossible to sacrifice 500 lives (or 50 if the re-vaccination strategy is actually sufficient) to protect the other 280 million even when the situation clearly called for it. Accept for the purposes of argument that we shouldn’t go ahead with mass smallpox vaccination now; still, we will face similar choices in the future, if, as seems only too likely, we have entered into an era of asymmetric conflict with biological weapons among the potential threats. That is not a world in which a bias toward inaction in the public-health arena will serve us well.
[SMALLPOX THREAD starts here.]