Monday, July 16, 2001

Science--a Human Activity

From the San Francisco Chronicle's Jon Carroll, July 16, 2001:
Science is not some monolithic body of knowledge; it's a mishmash of old beliefs, new beliefs, superstitions, guesses, counterarguments and disputes. It's not useless -- far from it -- but it has to be understood as a cultural artifact, a production of the flawed human mind....

The polygraph, the "many writings" machine, measures small changes in heart rate, respiration, perspiration and other bodily functions. The theory behind the polygraph is that people who lie get nervous when they lie, and the nervousness is reflected in the polygraph results....

The reasons that people get nervous are many and various; only some of them have to do with guilty knowledge of a crime. There are sociopaths who have guilty knowledge, but it does not make them nervous. And there are tricks -- you can bite your tongue at odd times, for instance, to confuse the "control" responses.

Indeed, one of the interesting things about polygraphs is that they are only as good as their operators. An experienced polygraph operator can tease info out of data that others cannot. It seems like science, but it's actually intuition....

A thermometer, for instance, does not require intuitive interpretation to be useful. The thermometer, we may say, is good science -- provided it is placed in the right location and calibrated correctly. The raw data of a polygraph may be as good as the raw data of a good thermometer, but the interpretation is just an art form, like Afro-Cuban dancing.

And yet, because we want to believe -- even though the legal system itself doesn't believe -- we keep using polygraphs. We keep attaching significance to their results, even though that's wrong.

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