The Precautionary Principle isn’t precautionary, and not even a principle

The Precautionary Principle requires that nobody should do anything that could come out very badly.Â  It sounds like a very sound but entirely different principle, which is that we shouldn’t do things whose odds of a very bad outcome are high enough that they aren’t good bets, but it isn’t; it’s fundamentally different.Â  Today’s performance of the PP shows that its real meaning is frequently “don’t let anything happen that I could be blamed for if it doesn’t go well.”

Certainly we can spend a lot of effort assessing “very bad” and “odds” to make risky choices.Â  But there is no escape from the idea of an operational definition, the bedrock scientific rule that a measurement must be reported with (or be understood implicitly with) the protocol by which it was obtained.Â  What are the operational definitions of the italicized words in the previous paragraph, when the PP is invoked?Â  Well, could often means “an ignorant monomaniac with an internet connection said so”, and very badly means “another such has spun out a fact-free fantasy or borrowed it from a movie”.Â  The PP is why ignorant people don’t vaccinate their kids: it endorses believing that a scissors only has one blade.

The superintendent of schools in LAÂ  closed 900 schools this morning in the face of an email threatening terrorism, putting a great city into complete chaos as parents missed work and tried to figure out what to do with their kids, not to mention losing a whole day’s learning, for which the district pays about $44m. All in all, a quarter of a day’s worth of the LA basin’s GDP is probably a good guess at the value Cortines and Garcetti put on a bonfire today for no good reason.Â  (In New York City, cooler heads prevailed in the face of the same “threat”.)Â  What would a responsible public official think about this decision?

(1) How does this threat look to a terrorist actually planning to pull off an attack?Â  It looks a lot like intending to minimize the death and destruction on tap, which is inconsistent with the whole idea from the get-go.

(2) How often are real attacks preceded by warnings? …warnings followed by actual attacks? Murders by death threats (domestic violence aside)? Bayes’ theorem, not to mention common sense, makes these questions central to the analysis.

(3) There is no avoiding risk, only choosing the right risks.Â  What can go wrong if we close the schools? Well, in addition to the immediate economic and social costs of the closure, we confirm to every crank and nutcase, and high schooler unprepared for today’s chemistry final, that any of them can close down the schools (courthouses? the Super Bowl?) with an anonymous email. These are pretty bad things to happen, and the LAUSD affirmatively chose to cause them with probability 1.0; not very precautionary, is it?

(4) Economist Michael Spence has given us the very useful concept of a market signal.Â  This is information seeking to induce this or that action whose credibility depends on it being (i) costly to send (ii) less costly when it is true.Â  The classic example is a used car guarantee: the car dealer might have to make good on it, so it’s not like “I am an honest man, and this is a good car! Really!”, and less costly if the car in question really is in good shape than if it isn’t.Â Â  An emailed threat of mayhem (never mind all the evidence of a low-capacity mind at work that struck the New York leadership about this one) fails both parts of the test.

The LA city fathers, incredibly, failed to order the immediate evacuation of their city this morning even though there is a real, non–zero threat of a great earthquake that will kill thousands, including children, if they don’t get out of town.Â  And after this incredibly irresponsible failure, I am pretty sure they will do it again tomorrow, and the next day!Â Â Â  If the safety of kids is everything to us, how are we letting our precious LA children out on the street going to school day after day, when almost one pedestrian a day, including a child every week, dies in LA traffic? Who votes for these heartless, reckless bozos?

Garcetti, save your people!



Author: Michael O'Hare


9 thoughts on “The Precautionary Principle isn’t precautionary, and not even a principle”

  1. Arrgh, I strongly disagree with the first sentence in the OP as a description of a useful Precautionary Principle. Sure the PP argument can be and has been misused, kind of like the slippery slope argument. OTOH, the PP has useful function.

    I see it as a burden-shifting argument. If I produce evidence that the novel thing you want to do has an unancticipated bad effect, then the burden of proof shifts from me to you over whether the novel thing should proceed. You need to show the bad effect won't happen or is less important than the good you can do. Rule of reason, not declarations by the ignorant, guide throughout.

    And also, email threats aren't novel. They're legion and mostly meaningless.

    1. The problem is that it's a burden shifting argument intended to spare the people who advocate a *particular* action/inaction any burden of proof. "Prove me wrong, or do what I advocate!" That you can't shift the burden away from people on opposite sides of a dispute at the very same time just gets ignored. You have to decide on some basis which side of a dispute benefits from the PP, so it doesn't really get you away from looking at the merits, if consistently applied. It just pushes the usual assessment process back one step.

      Say Trump advocates barring entry to the US by Muslims. (He didn't really, but let's run with it.)

      The PP says we should do this, because the alternative has the potential of admitting large numbers of terrorists.

      The PP says we should not do this, because doing so could radicalize large numbers of Muslims already here.

      How can we decide which the PP really says? We have to look at which really bad effect is more likely, and which has the worse potential downside. The PP doesn't really solve anything!

      Of course, the PP isn't meant to be consistently applied. It's meant to end rational evaluation of the merits in favor of an automatic win for the side invoking it. The other side generally realizes this, and rightfully dismisses the PP as worthless.

      1. This is not what the PP is, though. The Precautionary Principle applies where there is evidence of harm that falls short of a scientific consensus. In this case, the PP advises that we postpone any action that assumes that the existing evidence is wrong until the evidence has been either corroborated or refuted. But there has to be evidence.

        Obviously, there is considerable room for debate as to what constitutes sufficient evidence, but pure speculation ("… has the potential …") doesn't qualify.

        This is also what lies at the core of Michael's criticism: if we allow our actions to be governed by unsubstantiated fears, the outcome is paralysis (and more fear, and possibly a vicious circle), not substantive policymaking.

        1. Katja has it. Also, PP doesn't say "prove me wrong or do what I advocate", it says "prove the substantive objection I've raised is insufficient before you impose the new thing you want to do on the rest of us". The conservative case, Brett, is not to do something novel that's poorly understood.

          As for immigration, PP doesn't apply well. Both restrictions and openness have been done. PP works best on novel technologies.

  2. Aren't you a professor of public policy? You know how this works, right? No one remembers all the times the Powers That Be do the right thing as you've characterized it here. All they remember is the one time when the s*** hits the fan. There's essentially zero upside for any politician to behaving sensibly. Only downside. Another incident like this one – though smaller scale – that comes to mind affected me directly. Flying into LAX in Sept. 2005, I think, I discovered on arrival the entire facility shut down, with surface traffic backed up to the 405, and a mile hike in 90-deg. heat to the nearest clear street. The reason: an elderly Japanese traveler had an old flashlight in his luggage, whose decayed battery burst ("exploded") when handled by a TSA agent. The result? Snipers out on the roof of all the terminal buildings, traffic shut down, all outgoing flights delayed/cancelled for the remainder of the day. Obviously this was a totally disproportionate reaction. But what was the upside for anyone in the command chain to acting sensibly? Zip. This is our own (collective) fault for thinking that life can be made risk free, demanding that it be so, and not assessing the consequences to trying to make it so. It's not the fault of the administrators and executives, unless you really expect them to act entirely selflessly and with no regard to their careers.

  3. The fact that the emailed threat was not a credible market signal does not count strongly against it (unlike the other reasons you give). A “Beware of the dog!” sign is cheap to put up; but that does not make it automatically vacuous. The intending trespasser should at least check out the yard for signs of pit bull life.

    I could add to your list that many parents would not have been able to make alternative care arrangements at zero notice, so a fair number of children were left to their own devices for the day: free to wander the streets, play in unsupervised swimming pools, experiment with power tools and members of the opposite sex (hopefully not at the same time). Did nobody think of this?

    1. The second paragraph is what immediately came to my mind. There was reportedly even a requirement for parents to bear ID when they came to pick up kids who had already arrived at schools before the closing was announced. With more than half a million kids enrolled, we're talking about a loss in the single-digit millions of dollars. (Which, by the way, may go against the "nobody remembers" argument — everybody remembers when their day gets whomped by a hoax. Callously speaking, fewer people would have been affected if there had been an attack and the schools had been open.)

  4. You aren't completely wrong, there are aspects of a cheap shot here.

    First, according to the LAT… the NY police knew about the LA threat when they made their decision, but LA did *not* know about the NY one. I hope/assume there is some effort being put into someone figuring out why the bleep that happened.

    Second, there is a learning curve. It's like with plane hijackings. No redblooded Americans will ever follow directions again — they will attack. Because now they've seen the movie. LAUSD will probably not fall for this again – and let's hope they don't over-correct. One way to help people not over-correct is to … not make fun of them!

    Now as to the earthquakes, well. I can't really speak to that since I don't have any stored supplies either, except for some water and some garbage bags that, if it came to that, I could use to… well anyhow. The list of stuff you're supposed to have is several hundred dollars long. So this should be no surprise. Seems to me we ought to maybe stockpile water bottles, so people don't go berserk, and also think about insurance for all the Mom and Pop stores. Expecting regular people to be sensible all the time is dumb.

  5. "What would a responsible public official think about this decision?"

    He would probably think that the parents of the kids in his care couldn't give two shits about anything but their kid's safety, including his concerns. And they would probably think that until school was disrupted so often that education was impossible, that any threat made by someone who was not a giggling adolescent needed to be taken very seriously.

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