For most folks, the definition of an expert is someone who seems to know more than you. When I say ‘seems to know’, this is where BS artists and bluffers enter the game. And then there is impostor syndrome.
The legal definition
In legal proceedings, to a first approximation, the thing that defines an expert who can testify as such is someone who has relevant knowledge, skills, training, education and/or experience beyond that of the normal person in the area of their testimony. I like that definition in the sense that it makes general sense, and it allows facts to be brought to bear with regard to acceptance as an expert by the courts. Of course people can lie about these things, but then they may be subject to prosecution for perjury and of course the other side is looking for weaknesses and has the right to challenge the assertions of expertise.
Checking it out and risk management
When you think about it, the same thing can be reasonably applied for anything from employment, to consulting opportunities, to the clerk in a store. Get the claims, compare them to the facts, and trust based on these factors as verified by checking references. Background checks can also be used, calling up the references, and so forth. If they claim publications, you can find and review them, or have your internal experts review them if you want to be more certain. The more certain you want to be the deeper you can go to check things out.
Impostor syndrome
There are actual impostors and legitimate experts who worry that they don’t know enough to get the right answers all the time. The desire for perfection leads to real experts believing they are going beyond their actual expertise, which leads them, in many cases, to tell their clients that they are uncertain of their results, and more importantly, doubting themselves. The best outcome is when experts engage other experts to check on themselves and their results. That’s what we tend to do.
A simple truth is that, except for the things we do day after day in the same way with the same mechanisms, and by the way these are the things most easily automated, everything else requires that we go beyond what we strictly know into the realm of the uncertain. As a consultant and advisor, I am almost always doing something at least a bit different from what I have ever done before. I feel as if I am an impostor from time to time, even in areas where I probably know more than almost anyone else you can find.
Conclusions
If you are looking for experts, you need to find a way to determine whether they meet your needs. Most people rely on social proof of one sort of another, typically a referral from a friend or colleague. That’s how I get most of my work, but it’s also called the old boys network (even if it often involves women). A better approach is the method used by the legal system, if it’s important enough to justify calling in an expert.