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Scientific certainty in an uncertain world : Comments
By Kellie Tranter, published 24/3/2010Scientists aren’t scare-mongering when, almost unanimously, they describe the challenges we face with climate change.
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Your opening remark regarding the so called “precautionary principal” betrays a lack of understanding of “decision theory.” In any diagnostic situation one is challenged as where to locate the threshold level. One side of the threshold the test is positive, the other negative. Every test or battery of tests has four possible outcomes namely: true positive, false positive (FP), true negative, false negative (FN). Judgment is required in setting the FP and TN rates so as to maximise the pay-off. Increase the FP and automatically the FN deceases, or vice versa.
It is clear that you regard the threat of irreversible damage as so serious as to justify an exorbitant high FP rate for fear of that you may miss a positive call. In other words call every test for climate change positive, your FN rate will be zero, but your test will have no predictive value. Do you not care about the monetary and economic costs (including opportunity cost of spending money in more useful ways) of a FP result?
You refer to decision making by a court of law. My understanding is that in civil cases on 51% certainty is required (balance of probabilities) well in most scientific work the level for statistical significance is set at lease at 95%.
There is not space here to discuss the theory of causality in science. However, it could be argued that the seven criteria given in your paper do not meet the criteria given by the late statistician Sir Austin Bradford Hill.
In any case your phrase, “…isn’t there a common sense general argument in support of action……” To re- use your quote from the writings Leah Ceccarelli; your claim is but “sophisticated sophistry.”