On WEIT, Greg Mayer quotes Bertrand Russell on the idea of consensus or expert opinion:
(1) that when the experts are agreed, the opposite opinion cannot be held to be certain; (2) that when they are not agreed, no opinion can be regarded as certain by a non-expert; and (3) that when they all hold that no sufficient grounds for a positive opinion exist, the ordinary man would do well to suspend his judgment.
I think he’s right and as usual, he puts it wonderfully. It’s almost like poetry. As Mayer says, Russell is not talking about how or what to believe, but about when and where to doubt. We shouldn’t accept that – say - climate change is true just because lots of people say it is, but there’s every justification to accept the consensus of experts if there are demonstrably good reasons for them to say what they say. That – in a nutshell – is science.