With respect to expertise, there may be at the least the following considerations:
1 – How well does the expert know the subject matter of his discipline?
2 – How much experience has he had in trying things out in the world, to see if the theory actually is applicable?
3 – How much time does he give to reflection about his discipline?
4 – Does he go back and refresh his knowledge at frequent intervals?
5 – How bright is the expert? I consider humility, open-mindedness and reflectivity aspects of intelligence, although they probably don’t show up in IQ tests.
6 – How much real world smarts, as opposed to academic smarts does the expert possess?
7 – How concrete is the discipline: is it one with directly observable effects, able to be seen and repeated in real time (e.g. materials science versus string theory).
8 – How useful is the existing body of knowledge of the discipline in explaining and controlling the real world?
9 – How much money, prestige, careerism, etc. adhere to the discipline?
10 – How willing is the expert to consider other points of view? When an expert is wrong, they will often hold fast to their dogma beyond all reason.
11- How many competing and even contradictory schools of thought are in the discipline?
Undoubtedly more will come to me, but in the end, there is not a lot of reason to trust the experts, since they are frequently wrong, and in some disciplines, may be right only at the level of chance. However, at least listening to the experts is probably the best we can do, since the non-experts are not likely to be even as good.
We are doomed.