The New York Times reports that Europe is gradually approaching the point of decision on whether to allow genetically modified corn. Because of WTO rules on such things, the EU is required to base its policy on “science” if it want to keep out mutant corn from the US. This reflects a deep, deep misunderstanding of what science can contribute to policy.
Let’s start with the basics. There are two sorts of error we can make in this uncertain world, Type I (the risk of believing something to be the case when it is not) and Type II (the risk of not believing something to be the case when it is). Science is, among other things, a human enterprise organized around the systematic minimization of Type I error. Experimental protocols are about this, and so are the conventions we follow in determining statistical significance. This obsession comes at the cost of permitting greater Type II error, but that’s OK. Science operates on the basis of a vast division of labor, where each scientist’s work depends on the reliability of the methods and results carried over from what others have done. One false conclusion, if not noticed in time, could invalidate the efforts of an entire research community. This is why a serious Type I error is a potential career ender, whereas an avoidable Type II glitch simply diminishes a researcher’s list of accomplishments.
This single-minded insistence on avoiding Type I error is the reason why science is the one truly progressive human activity. Today’s science is better than yesterday’s, and tomorrow’s will be better than today. You can’t say this about poetry or politics.
(It is also, in the end, why economics is not a “real” science: it is no big deal for an economist to claim something to be true and to later discover that it isn’t.)
Policy, on the other hand, has to take Type II error as seriously as Type I. Take the Bt corn case before the EU, for example. It is a problem if regulators falsely think Bt corn is dangerous and ban it, but it is also a problem if they falsely think it is not dangerous and allow it to be used. A reasonable first cut is the standard cost-benefit approach: value each sort of error in terms of its cost function. Thus the cost of banning Bt corn is the probability of Type I error (falsely believing it to be harmful) times the economic cost of not taking advantage of this technology, whereas the cost of not banning it is the probability of Type II error times the cost of the damage it would do in that case. You go for the lowest cost option.
(There is an even better approach, as I argued here, based on the fullest possible utilization of information.)
The difference should be obvious. Science is radically asymmetric in the way it treats uncertainty: avoiding a false positive is everything. Policy is more balanced: failure to see is potentially as harmful as seeing what isn’t there. If you happen to be the sort of person, as I am, who thinks environmental risks are particularly important to avoid, you might tilt the policy calculus on issues like Bt corn toward less Type II error, even at the expense of more Type I.
Science has one job to do. Policy has another. They follow different rules.
7 comments:
Peter, you are as aware as anybody here how easy it is to manipulate cost-benefit studies.
'Type I (the risk of believing something to be the case when it is not)' -- juan purchases fresh tomatoes at the local grocery; by all appearances these are, even if slightly too firm, nicely ripened and ready for consumption. With the first bite, juan knows that while these tomatoes can rightfully be taken as what they are, they are not, but tasteless, poorly textured, largely inedible red objects which - in a 'experimental fit' - are placed on a window sill. Once a week juan examines them; two months pass and, by appearance, they have remained as they had at purchase (though upon slicing, evidently dehydrated). The tomatoes are safely disposed of..
well, i lost track of which was which
but just to clarify
possible error I: we reject GMO's wrongly. consequence: monsanto fails to make money on its GMO investment.
possible error 2: we fail to reject GMO"S wrongly.
consequence: end of agriculture from sustainable small farms in the "undeveloped" world to widespread species collapse in the breadbasket of America.
but it's okay, because SCIENTISTS tell us nothing can go wrong.
I like the analysis, and, of course, the Bt corn issue is based upon the potential for increased profit, but there is a deeper issue. That is, how to determine what to do when the information is inadequate?
Peter Dorman proposes the "do no harm" argument. Those promoting the use of Bt corn claim that there have been enough studies done so that the risk of harm has been reduced to an acceptable level. Since science never gives an absolute answer, those who wish to prevent some program can always claim that all the evidence isn't in yet.
The question thus becomes how is one to judge the level of risk? Most people can't understand the scientific studies and thus depend upon "experts" to judge their validity. How do we know that the experts are impartial or knowledgeable enough to be trusted?
Perhaps during the early part of the 20th Century scientists were given too much credit for wisdom and we ended up with some spectacular disasters as a result (Chernobyl, Thalidomide) , but the pendulum seems to have swung too far in the other direction now and many worthwhile efforts are hampered by those for whom no amount of evidence is ever enough.
I'm always leering of giving examples, because the anti-science nuts will jump on them, but here are a couple of random examples. Fluoridated water, thimerosal preserved vaccines as a cause of autism and the reverse: claims that some nostrum is being ignored by science but that it can treat or cure everything from arthritis to cancer.
It is clear that modified crops have had enormous benefits in various parts of the world, the issue about Bt corn is not of the same nature. One can raise crops without it which will cost about the same if labor is cheap enough. What is different is that patent laws now allow companies like Monsanto to dictate the use of their products and make farmers dependent on them for new seeds each year.
This is an economic and social issue, the science is being used as an excuse so as not to have to address the increasing power of "intellectual property" owners.
feinman
it's funny how i got to be an antiscience nut after teaching it for so many years.
maybe i just got better and better at criticizing articles within the discipline, so it was pretty easy for me to see what was wrong with the articles that went outside the discipline while claiming the mantle of "Science."
now i don't claim that every "antiscience" argument is based on profound wisdom, merely that most of the pro science articles are based on bad logic and bogus appeals to authority.
perhaps among the examples you offer, the one most worth looking at closer would be "modified crops have had enormous benefits..."
benefits to whom? compared to what? and does that eliminate.. say to the standard of Pascal's bet...the risks of GMO's going "wild"?
Coberly, if you don't think the "green revolution" which started in the 1960's had enormous benefits to those living at subsistence levels then you need to get out more.
Most of the advances were made using standard crop breeding techniques, it was just that systematizing this allowed for much more rapid progress then the hit or miss methods used by farmers in the past.
This is different from what is being done now where foreign genes are being introduced into plants. Whether this is a good idea or not seems to depend upon the individual case.
That there is some bad science (or even non-science being trotted out as science) does not alter the basic promise of science. The scientific method is the only way we have found to date to make progress in a systematic way.
You seem to want to throw the baby out with the bath water.
feinman
i never proposed throwing the baby out with the bath water. i just object to drinking the bath water and calling it Science.
There are some articles you might find about the Green Revolution which are not as enthusiastic about its effect on the welfare of the local farmers, but I am not familiar with the actual science (as opposed to Science) so I'll leave it to your interest level to investigate.
Similarly your faith in "it depends on the individual case [of GMO]" is charming, but not scientific.
As for the scientific method. Yes, by all means. You might want to try following it some time, about something you are interested in enough to think carefully about. But don't ask me to worship Science because you have Faith in The Scientific Method.
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