I believe we should listen to expert. But, I differ on defining an expert.
An expert is one who is good at doing. Someone who does gets better at what he or she does. An expert piano player is one who plays the piano well. An expert chess player is one who plays chess well.
By contrast, a historian is one who studies history. He or she is an expert at studying history. But, applying knowledge of history and predictions are a whole different animal.
A piano historian might know about many types of pianos. He or she might know about the difference between a clavichord and a piano. He or she might know who the greatest pianists of the generation were. However, all of that means nothing when sitting down to play.
A historian can study history well. However, what does that matter? We should know our history, yes, but, it's history. The earth is an exceedingly complex system. So are people. One cannot possibly know or consider all there is to know or consider. There's not enough data and not enough good data.
Moving on to epidemiologists. They study diseases. They're experts at studying diseases. That's it. That's all. They aren't experts at risk management. They aren't experts at public policy. They aren't experts on group psychology.
Of course, they're free to recommend solutions for anything they want. They are free people. But, what weight should we give them? As soon as they venture out of studying a disease they're no longer an expert.
They can tell us the differences between diseases. They can compare and contrast. They can trace the history. That's what they do, they study diseases. Can they predict the future? No. Can they predict how people will react? No. Those aren't their fields.
I want to be a bit nuanced here. Science can help us make policy. But, everything must be taken in concert together. And, the systems are very, very complex. There are things that can be done well. But, normally, that's not what happens. Hence, I bash experts.
I want to extend these thoughts a bit more. First, studying and the difference between research and knowledge. Second, the problem of narrow fields. And, third, the underlying issues of science.
In programming there's a term tutorial hell (read more). The general concept is that people follow tutorials. They then have a surface level knowledge. But, they can't apply it. They can't build things without a tutorial. So, they follow more tutorials. Thus compounding the problem. The solution is to do. Go out and do.
They are the people who study programming. They read and watch videos. They know all the buzzwords. But, they can't sit down and apply it.
On Narrow Fields
It's easy for someone studying a field to apply limits to it so it's easy to understand. If you remember economics, we talked about the supply and demand curve. That's great, it makes sense on a conceptual level. But, it's too simple for the real world. It assumes people make rational decisions and have an unlimited ability to process information.
Then, we got behavioral economics. That's kind of the merger of psychology and economics to explain the shortfalls. From EconLib.org:
The standard economic model of human behavior includes three unrealistic traits—unbounded rationality, unbounded willpower, and unbounded selfishness—all of which behavioral economics modifies.
One can study economics for decades and still not be able to apply it, because it ignored key aspects. The goal is to complicate economics to make it more applicable (Boston Fed, PDF).
That's on a complex field already. People can't work in narrow fields and expect to understand the world. Because people aren't rational and are hardly predictable.
On Human Behavior
The human behavior issue is a big one. People are complex and strange. If you think someone is normal, you just don't know them well enough, yet.
Humans are the scientists. That's a problem because it introduces errors into science. And, it takes time to correct. People are greedy, so companies can buy studies (CNBC). And, many times scientists don't agree. I can find a study for practically anything.
Do you remember the stories about the sugar industry paying to manipulate science? Here's a story about it from the New York Times.
That's the problem. What we know and truly know is very malleable. We can know whatever we want to know. And, we can find support for it from sources. When people are the subjects (like here with the affects of sugar) there will always be questions. But, what about hard science? From Richard Feynman:
We have learned a lot from experience about how to handle some of the ways we fool ourselves. One example: Millikan measured the charge on an electron by an experiment with falling oil drops, and got an answer which we now know not to be quite right. It's a little bit off, because he had the incorrect value for the viscosity of air. It's interesting to look at the history of measurements of the charge of the electron, after Millikan. If you plot them as a function of time, you find that one is a little bigger than Millikan's, and the next one's a little bit bigger than that, and the next one's a little bit bigger than that, until finally they settle down to a number which is higher.
Why didn't they discover that the new number was higher right away? It's a thing that scientists are ashamed of--this history--because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong--and they would look for and find a reason why something might be wrong. When they got a number closer to Millikan's value they didn't look so hard. And so they eliminated the numbers that were too far off, and did other things like that. We've learned those tricks nowadays, and now we don't have that kind of a disease.
We must continue to study and learn. But, we must also apply. And, we must be cognizant of the limitations. There are a lot of limitations to human knowledge. Those must be considered with respect to policy and decisions that affect everyone.