The Certainty Principle
One of the most effective ways to delay action on an issue, or to promote a political ideology, is to insist on scientific certainty before any action is taken or an idea is accepted. This technique has been used by, among others, those who oppose environmental regulations, those who promote creationism and those who deny the Nazi holocaust. Such demands for certainty can sound very reasonable to the general public, but those familiar with science recognize that such scientific certainty does not exist. Often this sense of reasonableness is enhanced by presenting "real science" as being about certainty. For example, Michael Sanera and Jane Shaw in their book Facts, not Fear use the example of a scientist who repeats his experiment over and over, getting the same results each time. They also claim, incorrectly, that well supported hypothesis become theories, and that well supported theories in turn become scientific laws. (See How science does not work for more.)
There are various ways to use the certainty principle. One is to repeatedly claim that the science is uncertain, and that more study is needed. This demand for ever more studies has been termed "paralysis by analysis". Another method, which seems to be increasingly popular, is to demand that regulations need to be based on "sound science". There does not need to be any proof of "unsound science", simply bringing up the term "sound science" is enough to derail or at least postpone action. Another favorite claim is that such well established scientific ideas as evolution and global warming are "only theories", confusing the common and scientific definitions of a theory. sometimes it is pointed out that "some scientists disagree" without noting who these scientists are, or what their qualifications are (appeal to anonymous authority). In a few cases, uncertainty is simply invented. Perhaps the most famous in the environmental field are Dixy Lee Ray's claims that there was some great mystery about how heavier than air CFCs reach the ozone layer, or how they got from the Northern Hemisphere, where most of them are used, to Antarctica where the first ozone "hole" appeared. But as Robert Parson has pointed out, both of these events can be explained by atmospheric science that was well understood long before there was any concern about ozone depletion.
In many cases, it is possible to use multiple levels of uncertainty. For example, with global warming the following uncertainties are possible:
Not sure that humans are causing the increase in greenhouse gases.
Not sure that the Earth is warming.
If the Earth is warming, it is not sure that it is caused by increase greenhouse gases.
Not sure how much, if any, the Earth will warm in the future.
Not sure what effects the warming, if it does occur, will cause.
Additional reading
NEW In Angels and Extinctions Carl Zimmer writes about what he calls the Imperfect Knowledge gambit (what I have called the Certainty Principle).
NEW In How industry hijacked 'sound science' Oliver Houck notes that 'sound science' really means an unobtainable level of certainty, and that the term is used to derail environmental and health regulations
NEW Uncertain Science... Uncertain World by Henry N. Pollack
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Written by Jim Norton
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