Laypeople Cannot Decide for Themselves

The belief that a layperson can examine the scientific evidence and decide for himself is very common and completely wrongheaded. A layperson simply does not have the body of experience to correctly interpret evidence in technical fields consistently. I heard an interview with Stephen Barrett, a retired doctor who now runs the medical fallacy tracking website Quackwatch, who has many examples of people coming to the wrong conclusion using this approach. The right method is to find

credible experts to evaluate evidence for you. This is why a consensus of trained professionals should carry weight. The lone decrier can be right, but almost always isn't. With complex issues, the trend is that over time, the evidence grows stronger if there is a real phenomenon. Take ghosts as a counter example: more than a hundred years of people looking and the state of the evidence is essentially unchanged. Finding one crank scientist who believes in them doesn't count for a whole lot.

I wonder if it is arrogance or simply ignorance that lies behind this notion. Well, first off the layperson is not examining the evidence. Take medical research as an example. To look at the raw studies (just getting the data would be a lot of work) he would need a very good working knowledge of statistics to evaluate the results as well as an understanding of the relevant medicine to judge the assumptions of the experimental structure. A layperson cannot possess all this knowledge by definition. If he did, he'd be an expert. That means that a layperson claiming to be judging the evidence is actually using other people's interpretations of that evidence. If he's not aware of that it's ignorance: check. Once you're at that stage, who you choose to interpret facts for you becomes critically important. Depending on your level of knowledge, you may not have the skill set to even make that decision with any certainty. It is of course true that minority opinions among a body of experts can prove ultimately correct, but the overwhelming majority of the time they won't. For a layperson to think that he can spot those few times more accurately than the trained professionals who specialize in that field is absurd. It makes an assumption that the layperson's largely uninformed opinion is more valuable, allowing him to dismiss the judgements of others. Since arrogance is all about thinking that your abilities trump those of others you have never met (therefore being a form of bigotry), I would argue it fits in this case as well. Arrogance: check.

What about the implications of all this? Does it mean that a layperson is never really entitled to an opinion of their own about technical matters? I guess it depends how you define "technical". If you define it as a complex field that requires a lot of cumulative knowledge, the I guess I'd have to say "yes", a layperson can never have a valid independent opinion. The key phrases I've used in this posting are "for himself", "of their own", and "independent". One option is to simply defer to the opinion of the trained community that studies that subject. You can have a very valid opinion as to the state of consensus within that community, but that is something that's comparatively easy to evaluate. Alternately, the layperson could undertake the study required to become an expert. That would give him an equal voice, however, not a definitive one. The next best thing would be for a layperson to run his interpretations past actual experts in the field. When a layperson rejects the judgments of those significantly more knowledgeable in his area of interest is when there's a problem.