How does one discern who are experts in a field that is unfamiliar to him/her?
How does one discern the pseudo experts (those seem to be experts but are not in reality) in an unfamiliar field?
Clarification : I am interested in principles and general philosophic guidelines, not in specific actions (google the person).
If you are really not knowledgeable in the field and outside of the basic verifications like googling the person's name, your best bet is to see how consensual their position is in the field.
The cliche of the genius scientist who is right against every one else is mostly just a cliche. Of course every great discoverer who have had a correct hypothesis before everyone was at one point the only one to support their own theory, but at this level we are talking about cutting edge topics in the field you, as a layman, wont be able to comprehend anyway (imagine someone trying to find for themselves if relativity makes sense in 1905 although they barely master high school level Newtonian physics: disaster guaranteed).
But if said person has consensual views on the rest of the field, they are more probably an expert that someone who claims to revolutionize the field from the bottom up (Relativity is compatible with Newtonian physics, it does not throw everything to the garbage).
So listen to what other people in the field are saying of this person and what they have to say on a particular topic. It might require patience, as real experts are mostly busy doing research and not going from interview to interview to say their opinion about the last quack who makes the buzz.
A good recent example is Luc Montagnier, a biologist who got the Nobel prize for isolating the HIV virus in 1983. At first glance, a Nobel should be a good hint that he is indeed an expert. Problem is, things went south from there and he was found afterward arguing for homeopathy and more recently raising fantasist claims that the Covid-19 was manufactured (*). Luckily, although his Nobel prize if enough to fool journalists and laypeople, most biologists consider him to have become a quack. This is a good cautionary tale about the fact that past achievements do not guarantee future successes.
(*) I am not taking position about the origin of Covid-19 here. Whatever we find it to be in the future, Montagnier's claims are fantasist, made for bad reasons, and if he eventually happens to have been right it will be by accident.
Studies of job interviewers have shown that to in order make the correct judgement, you have to be an expert in the field yourself. Interviewers who were not, such as Personnel or HR staff, were unable to tell and made wholly arbitrary judgements.
So you need to ask someone whose position can only be due to genuine expertise. At least if they have a Professorship or a Nobel Prize or founded a trillion-dollar company or head a professional association or something like that, they are unlikely to be any more pseud that the field itself, and will be able to give you a straight answer.
The traditional ways are as follows.
First you google their name to see if they are active in their professed field and in other areas which would offer clues as to their expertise and legitimacy.
You ask where they were trained, and look that place up to see if it exists and is legitimate, then you verify that they actually earned a degree there. You also search on that place name to see its history and mission.
Then you examine their publication history, to see if it is legit (this includes searching the history of the publisher to see if the journal exists and is legit). If they appear on linkedin, you can read testimonials and get references.
I think the best way to know this is to try to master the field yourself. Then you can judge if a crackpot is a crackpot or if he really cracks. What do you have to base your judgment on? If the scientist, expert, is holding a view that's divergent from the established view, the expert is usually considered a pseudo.
But pseudo-experts can turn out to be pseudo-crackpots. The development of the atomic theory in the field of physics is an example. Democritus already claimed the existence of atoms, the indestructible small entities can have a variety of forms. To stick to these forms in modern times (and make propaganda for it) is tantamount to being pseudo or crackpot, in the eyes of physicists advocating atomic theory but not the forms Democritus has in mind.
His theory of basic units was good but not the things used as the basic units. Putting forward the idea of atoms being something different as they are supposed to be in modern atomic will almost certainly be considered a pseudo-expert move, or even a crackpot move.
In classical thermodynamics, substances are seen as continuous and divisible on every scale. At around the same time as the classical case came into existence statistical thermodynamics came into existence too. Both theories were equally valid in that time. But proponents of the classical and proponents of the statistical didn't consider each other pseudo or crackpot, I guess.
Maybe it should have been good if they did. It would stimulate each other to think of experiments in favor of the assumptions of the theory in question. "I'm not a crackpot! If you perform an experiment like the one I have in mind you will see... So my assumption is right."
Another example is the use of quantum mechanics s use in a broader context than physics. Usually, people using it in this way are considered pseudos. Even if their knowledge of the subject is broad and accurate, the way they use this knowledge is often considered a pseudo use, as it is supposed to be applicable for physical reality only. Fritjof Capra is considered a crackpot by many of his fellow physicists, but he has a Ph.D. in physics.
When it comes to the interpretation of QM then you can consider the minority of interpretations as pseudo. The minority can also the majority as a crackpot. So it depends. The Copenhagen interpretation is accepted as the correct interpretation. And even the divergent (pseudo) view on the interpretation can be seen as stimulating. The Bell experiment was devised to rule out (or confirm) divergent interpretations like hidden variables. One could argue that the Copenhagen interpretation would be the common one these days when the Copenhagen convention didn't happen and powerplay didn't take place.
Sheldrake has a Ph.D. in chemistry, But he too is considered a crackpot. So being an expert does not mean that you automatically can't be a pseudo expert. It depends on how you use the knowledge of your field.
This particular example of a physical theory and its interpretations can be extended to other theories. Say the theory of evolution as understood by Dawkins. Who is considered a pseudo expert in this case?
To summarize, pseudo-experts are recognized by their divergent use of theories. The normal use is determined by other users of the theory and it could be that the normal use is determined by how many users are practicing the theory. Social (peer pressure) and psychological matters come into play. Maybe even economic, biological, geographical, or even political influences come into play just soo in determining what is pseudo or not.
So you can find pseudo-experts where ever are experts. If they have a significant influence they will certainly be recognized by the experts who will argue against them.
You can tell who are the real ones and who are the pseudo ones by reading about them and see what the experts have to say (if you have no knowledge of the field). But the pseudo can always turn real and the pseudo can always have a positive influence on the real.
