Trust the Experts: A Reasonable, Defeasible Presumption
By Bryan Caplan
It is not the scientific consensus that makes me believe that there is a link between smoking and cancer. It is the evidence for such a link that is compelling. It is the weakness of the evidence of the link between man-made carbon dioxide and climate change that makes the scientific consensus less persuasive than the tobacco-cancer link.
Sincere question: Have you personally reviewed the evidence on smoking, Arnold? I haven’t. I believe that smoking causes cancer based on scientific consensus. The same goes for virtually all of my beliefs about the hard sciences, with the exceptions of genetics and evolution.
Is there anything epistemically wrong with my approach? I don’t think so. The presumption that experts know more about their subject than laymen is eminently reasonable. Of course, it’s a defeasible presumption. If you audit the experts, and discover that their objectivity or evidence is weaker than you would expect, then it’s reasonable to downgrade them. I do it frequently, and Arnold’s impressions from the global warming conference confirms my suspicion that this is one of the issues where expert consensus means less than usual.
Still, Arnold seems to be saying that you should base all your beliefs on direct examination of the evidence, and ignore expert consensus. I just can’t buy that – and I wonder if Arnold really buys it either. Arnold?