Whenever I see 'expert status' debated at universities, where it is debated and criticized a lot, my alarm sirens go up. You can split hairs about what really constitutes an expert for many hours, I've even been to conferences about this topic. But funny Niels Bohr paraphrases aside, it's in reality very simple and not problematic
at all who constitutes as an expert:
- Experts have 20-40 years of experience in a particular field within their discipline. Young scholars or those belonging to the academic middle field need not be counted as experts. (They may still be experts, but that doesn't mean you should resort to them for providing expertise.)
- Experts have 20-40 years of continuous publications in peer-reviewed international academic journals about the subject matter, or have been working in the field for that time in a senior role in non-academic fields (e.g. race driving, casino security, etc.).
- Experts are recognized as eminent scholars by the majority of fellow scientists who also work in the field, whether they agree with them or not. Not just scholars or average scholars, eminent scholars.
- The expert's discipline is an actual science and their field of expertise is in fact a subfield of that discipline. Fields are much narrower areas of specialization than disciplines. (Hence, priests are not experts about 'what's good', astrologers are not experts in astronomy and mechanical engineers who muse about special relativity are not experts about special relativity.)
- The expert is given the intellectual independence and has sufficient access to the evidence needed to provide his expertise.
These criteria really suffice to weed out all the pseudo-experts of the world. That's because most if not all pseudo-experts are either laymen or crackpots from related disciplines, and in any case are not recognized as eminent scholars from people of their field. Someone can be an expert without satisfying these criteria, Richard Feynman on the Challenger catastrophe, for instance, but if you want to make sure, the above criteria suffice.
Last but not least, nobody is forced to believe genuine experts, but he should also be prepared to defend his points of view as well as a genuine expert or be regarded a stupid assclown if he doesn't.