domingo, 10 de março de 2013

Verdade científica oficial

Official Scientific Truth 

David Friedman

A pattern I have observed in a variety of public controversies is the attempt to establish some sort of official scientific truth, as proclaimed by a suitable authority—a committee of the National Academy of Science, the Center for Disease Control, or the equivalent. It is, in my view, a mistake, one based on a fundamental misunderstanding of how science works. Truth is not established by an authoritative committee but by a decentralized process which (sometimes) results in everyone or almost everyone in the field agreeing.

Part of the problem with that approach is that, the more often it is followed, the less well it will work. You start out with a body that exists to let experts interact with each other, and so really does represent more or less disinterested expert opinion. It is asked to offer an authoritative judgement on some controversy: whether capital punishment deters murder, the effect on crime rates of permitting concealed carry of handguns, the effect of second hand smoke on human health.

The first time it might work, although even then there is the risk that the committee established to give judgement will end up dominated not by the most expert but by the most partisan. But the more times the process is repeated, the greater the incentive of people who want their views to get authoritative support to get themselves or their friends positions of influence within the organization, to keep those they disapprove of out of such positions, and so to divert it from its original purpose to becoming a rubber stamp for their views. The result is to subvert both the organization and the scientific enterprise, especially if support by official truth becomes an important determinant of research funding.

The case which struck me most recently had to do with second hand smoke. A document defending a proposal for a complete smoking ban on my campus was supported by a claim cited to the Center for Disease Control. Following the chain of citations, it turned out that the CDC was basing the claim on something published by the California EPA, which cited no source at all for it. As best I could determine, the claim originated with research that was probably fraudulent, using cherry-picked data to claim enormous and rapid effects from smoking bans. Pretty clearly, the person on my campus who was most responsible for the document had made no attempt to verify the claim himself, merely taken it on the authority of the CDC. For more details see my post on the case.

An interesting older case involved Cyril Burt, a very prominent British Psychologist responsible for early studies of the heritability of I.Q., a highly controversial subject. After his death he was accused of academic fraud of various sorts. The official organization consulted was The British Psychological Association, which concluded that he was guilty, a conclusion that many people then took, and some still take, for gospel. Subsequently, two different authors published books arguing convincingly that some or all of the charges against him were bogus. Interested readers can find a detailed discussion of the case in Cyrus Burt: Fraud or Framed, which concludes that much, at least, of the case against Burt was in error. I am not certain, but I believe that the BPA later reversed its judgement, withdrawing the claim that his work had been fraudulent. Perhaps one of my readers can confirm that—I did not manage to with a brief Google search.

It is natural enough that observers of such controversies want an authoritative answer from a authoritative source—quoting the CDC is much less work than actually looking at the research a claim is based on. But treating such answers as really authoritative is a mistake, and a pattern of treating them that way a dangerous mistake.

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