Chris Dillow:

It's a bad day for experts. The Times complains that economic forecasters are as blind as ancient soothsayers, whilst proof that Colin Stagg was innocent discredits Paul Britton's expertise as a forensic pyschologist.  To point out that experts are wrong, however, is to misunderstand the purpose of them. Their function is not to provide knowledge, and still less clear thinking. Instead, it is to provide certainty. People hate dissonance, doubt and uncertainty. Experts help dispel these.

So, Paul Britton's function was to tell the police that they had the right man, whilst economic forecasters' job is to provide an impression that the future is knowable; no-one wants to hear about standard errors, parameter uncertainty or the Lucas critique.  What's so pernicious here, though, is that people have ways of achieving an illusory certainty anyway. … 1. The confirmation bias. … 2. The halo effect. … 3. Groupthink. … 4. Ego-involvement. Admitting that we are wrong … [is] a sign that we are not the infallible, uber-competent professionals we think. We'll do anything to squirm out of facing this. …

And herein lies the purpose of experts. It's to reinforce these mechanisms, to help people avoid the uncomfortable facts that the world is uncertain, that mistakes are inevitable, and that we are not as in control of things as we think. Blaming experts for being wrong is like complaining that the economy is not yellow. It's a category error so howling as to be nonsensical.

OK, maybe Chris exaggerates; we do sometimes want experts more for info than certainty.  How can we tell when?  And how much does this contribute to resistance to prediction markets that give honest certainty estimates?  Hat tip Mark Thoma via Tyler Cowen.