All deaths are not equal

Right before New Year’s Eve, Andrew Sullivan’s blog saw some chatter about the tradeoffs between dying in a terrorist attack versus a car accident.  Apparently 113 Boeing 777’s must be exploded before terrorism can kill as many people as car accidents.  Yet people don’t scream for protection from their Buicks!  Bill Maher makes a similar argument in this entertaining video.

And why not?  A death is a death is a death….right? If our goal is overall safety, then surely the public should clamor for safer roads as much as they do for airports…right? Well, not quite.  As much as I agree that we spend too much on terrorism, both Sullivan and Bill Maher gloss over the important fact that deaths cannot always be treated equally.

Social science research has shown quite conclusively that these calculations inevitably involve a subjective value judgment on how to treat human life.  To quote Paul Slovic’s excellent paper:  “Simply counting fatalities treats the deaths of the old and young as equivalent; it also treats as equivalent deaths that come from immediately after mishaps  and deaths that follow painful and debilitating disease…”

Slovic continues to explain that distributional impacts (affecting black rather than white, poor rather than rich) and degree of control also affect risk perceptions.  People may be more forgiving if they knowingly engage in a risky activity as opposed to one where they are guaranteed safety.  We would, I hope, be very upset if a chemical plant discharge solely affects a community of poor, uneducated blacks even if only a couple dozen people died every year.   Calibrating our response to nothing more than total deaths elides these subtleties.

Along these lines, it doesn’t seem that unreasonable for people to demand strong government action on terrorism rather than automobile safety.  Perhaps they accept a certain risk of driving a car but don’t do so when flying a plane.  Perhaps they think getting blown up is somehow worse than a car crash.  Or perhaps they think we have done all we can to improve car safety but haven’t done nearly enough in other areas.  Again…accounting just for total deaths misses all this.

Maher et al. are of course free to say that we should treat car crashes and exploding planes equally.  They’re entitled to that belief.  But it represents their own subjective preference rather than a uniquely rational calculation.   Scientists’ acting otherwise is a main reason the public often sharply disagree with risk assessments.  Pretending our risk models are wholly rational also contributes to poor communication and mutual distrust.

None of this undermines the idea that we overemphasize the threat from terrorism.  I largely agree the sentiment.  But those arguments shouldn’t rest on a faulty analysis that simply sums total deaths in various activities.  While all lives should be treated equally, all deaths should not.

UPDATE: I meant to add this reference the first time.  Email me if you want a PDF copy.
Paul Slovic, The risk game, Journal of Hazardous Materials, 86 (2001), 17 – 24

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