Cost-Benefit Analysis and Airline Security – A Query about Method

In the various discussions about airport and airline security here at VC, a common response in the comments is something like this one (some version of this pops up from many commenters, and I’m just pulling up the most convenient example):

With the current procedures, flying is one of the safest things we do. Even with an occasional successful bombing, we would still be way below any level of acceptable risk. If we want to curtail civil liberties to save the lives of people flying, we should start by screening folks we allow to drive to the airport, you’re much more likely to get killed doing that.

It is a costs versus benefits argument (actually a couple of slightly different ones) pitting the costs of a successful bombing and “acceptable” risk, with a suggestion that an appropriate metric, by implication of preferring to regulate it instead, would be the drive to the airport.  It is a theme of much of the skepticism about US counterterrorism policies, a skepticism rooted in cost benefit analysis, but perhaps more accurately framed as skepticism about the proper things to be compared – what kinds of costs and what kinds of benefits?  Matthew Yglesias perhaps exemplifies the skeptical view following the Christmas attack, in a post titled “Not So Scary ‘Terror'”:

Obviously, people shouldn’t be lighting anything on fire inside airplanes. That said, all the big Christmas airline incident really shows to me is how little punch our dread terrorist adversaries really pack. Once again, this seems like a pretty unserious plot. And even if you did manage to blow up an airplane in mid-air, that would be both a very serious crime and a great tragedy, but hardly a first-order national security threat. [Edited out Peter King quote.] …

Ultimately, it does no favors to anyone to blow this sort of thing out of proportion. The United States could not, of course, be “devastated” by anything resembling this scheme. We ought to be clear on that fact. We want to send the message around the world that this sort of vile attempt to slaughter innocent people is not, at the end of the day, anything resembling a serious challenge to American power. It’s attempted murder, it’s wrong, we should try to stop it, but it’s really not much more than that.

I don’t think this is right, for a number of reasons, starting with thinking that it is not the right way to approach cost-benefit analysis – more exactly, what one should count as categories of costs and benefits to weigh against each other.  I’ve elsewhere partly explained my views on how cost benefit analysis requires a prior view of “plausible” comparisons, arguing that skeptics like John Mueller are making “inapposite” comparisons.  But I’m interested to know what VC commenters think is the right way to approach this; I think that “plausibility” and “appositeness” of comparisons matter, and in fact form an often-covert base of assumptions in applying cost-benefit analysis, whether to skeptical or non-skeptical ends.

So let me ask.  What is right or wrong with this skeptical approach to such things as airline security on the grounds, for example, that the ride to the airport is more dangerous, or that one’s chances of getting struck by lightning are higher than getting killed by terrorism, or that even if you did manage to blow up a plane, it is not a first-order national security threat?

Let me be very clear on the question.  I am not asking your views on airport security, terrorism, Matthew Yglesias, or such things, not directly.  I am asking readers to say what is right or wrong about cost benefit analysis used in these ways – and more particularly, is it okay or not to include all of these kinds of considerations as the “frame” for costs and benefits?  The skepticism assumes that a wide range of things can be included as points of comparison – is this right, and if not, why not?  And if not, what are the limits, if any?  No rants, please, and confine responses to the methodological question about CBA and its underlying assumptions.