“It is commonplace that in all kinds of questions the fool feels a certainty that is denied to the wise man. The semiliterate on the next bar stool will tell you with absolute, arrogant assurance just how to solve the world’s problems; while the scholar who has spent a lifetime studying their causes is not at all sure how to do this.”
-E. T. Jaynes[1]
Imagine you took a person who has been an avid basketball fan for decades, and another person who had just seen a basketball game for the first time, and you asked them both what a typical score for a basketball game was. It should be no surprise if the lifelong fan were able to give you a much better answer than the non-fan. Why? The fan has an enormous amount of information to base their answer on, and has spent a huge amount of time thinking about things like basketball scores. They understand the rules of the game. They’ve sat around with other fans discussing basketball statistics, subtleties of the game, strategy, etc.
That’s why we tend to trust the opinions of experts over the opinions of laypeople. Experts are experts precisely because they have more information, they’ve absorbed the relevant theories, and they’ve had their ideas critically analyzed by other experts. They have cultivated a deeper understanding than laypeople. Consequently, they are more entitled to their opinions than laypeople are.
Most of the time, laypeople realize when they’re out of their element, and on matters where they lack expertise they simply defer to the experts. If you want to know why you’re sick and how you might get well again, you consult a doctor. If you want to build a bridge that won’t fall down when you drive over it, you consult an engineer. Where we have more expertise, we should have more confidence in our knowledge. Where we lack expertise, our confidence should be shaky.
But that’s not the way it always works. Especially in certain domains, the least competent people also tend to be the poorest judges of their own abilities, and so they wrongly believe themselves to be much more skilled than they actually are.
Psychologists Justin Kruger and David Dunning demonstrated this effect, which is now named for them[2]. In one experiment they asked students leaving a psychology exam to estimate how well they had done. The students that had scored in the top half of the class were able to judge how well they had done relatively well, with the top scoring students slightly underestimating their abilities. But the students who had scored in the lowest 25% thought that they had outperformed the majority of their peers.
Dunning and Kruger’s finding was not an isolated result. They went on to find the same effect in tests among students taking logic and grammar tests. They found the same effect in debate teams’ estimates of their own abilities. They found it in hunters estimates of their own knowledge of firearms [3]. Other researchers found the same effect in medical technicians estimates of their knowledge of medical terminology and lab practices[4]. It even persisted when researchers offered subjects a $100 incentive if they could accurately estimate their own performance[5].
The researchers’ explanation is that, at least in some areas of knowledge, the skills you need to estimate your own competence are nearly the same skills that you need to have that competence in the first place.
“The skills needed to produce logically sound arguments…are the same skills that are necessary to recognize when a logically sound argument has been made. Thus, if people lack the skills to produce correct answers, they are also cursed with an inability to know when their answers, or anyone else’s, are right or wrong.”
-Dunning, Johnson, Ehrlinger & Kruger[6]
So, besides knowledge, the expert has something else the least knowledgeable people lack; the expert knows the scope and limits of their knowledge.
Other than those with the lowest competence, there is another category of people who are also prone to make highly confident but wrong claims; the sociopath. In addition to traits such as being manipulative and pathologically lying, sociopaths also tend to be very confident and assertive, and to have a superficial charm and a grandiose self-image[7].
So, despite the fact that you might expect the most knowledgeable, competent and highly qualified people to make the most confident assertions, the greatest confidence is often displayed by those either too incompetent to realize that they are incompetent, or by those who are knowingly lying to manipulate people.
Finally, consider that the media has a preference for featuring people who confidently make sensational and simple assertions. The result is a rather tragic conflict between science and journalism.
“Science values detail, precision, the impersonal, the technical, the lasting, facts, numbers, and being right. Journalism values brevity, approximation, the personal, the colloquial, the immediate, stories, words, and being right now. There are going to be tensions.”
-Quentin Cooper[8]
A legitimate medical expert interviewed about a complex medical topic will tend to responsibly explain that the issue is very complicated, explain what we know and don’t know, and quantify the uncertainty in our knowledge. Unfortunately, an objective evaluation of our current state of knowledge and uncertainty doesn’t always draw quite as large an audience as an ignorant sociopath spewing sensationalized nonsense with absolute arrogant certainty.
So, if someone confidently tells you that every cancer can be cured in weeks and table salt is mostly sand and glass, it might be because they’re an expert, but it might also be because they’re incompetent, or because they’re a lying sociopath.
If their claim is easy to test then you can always just go ahead and test it. For example, you could put some salt, some sand, and some glass in water and see which ones dissolve and which ones don’t. If it’s not an easy claim to test directly, you’ll just have to do a little more work, examine all the information available to you, and decide for yourself if their claims are justified.
Confidence can be seductive, but it doesn’t matter how confidently someone proclaims something to be true. Confidence is often a poor indicator of competence. What matters, as always, are observations and evidence, logic and reasoning.
