Expert opinion can be wrong. We all know that it is right a lot of the time, but sometimes we cannot understand the reasons why experts believe what they do. There are also times when experts do not agree with each other. There are even times when experts can to know things they do not know or in areas they have not studied. We often view experts as being more intelligent or smarter than us. This is incorrect. The only way that experts are different from us is by knowing more than we do about something.
Experts is just a name we give to people who know more than we do about a subject. So an expert in practicing medicine is a doctor, while an expert in law is a lawyer. Similarly, an expert in science is a scientist and an expert in philosophy is a philosopher. All of these experts did to become an expert was to learn the right kind of information about the subject that they are an expert in. Most of them did so by attending school. Most of them read books. There are times and situations in the past in which that was not true. Some experts, such as expert generals, gained their expertise from experience and personal training.
These experts are not smarter or more intelligent than anyone else. They have three advantages. First, they have learned the material and understand the subject that they are discussing. Second, they are interested in the subject. Very few people choose to become an expert only for the money, and those that do are usually bad experts. Third, they know how the subject works. So they know the various experts in their field, they know what sort of arguments are used in the field and they know some of the history of their field. All of these things do not make someone smarter. Many experts do not know how to reason correctly especially when they face an argument outside their expertise. They often misread their opponents. They often lack objectivity and are unwilling to admit that their favored theories might be false. Yet these are the exact opposite of what a truly smart person would do.
If these reasons are not enough, consider that experts often back theories that no one believes today. Aristotle, who was an expert of his time on science, believed that the world was made of four elements: earth, air, fire and water. Galileo believed that tides are caused by the rotation of the earth. Isaac Newton believed in the practice of alchemy turning lead into gold. Kepler believed that astrology told the future. All of these men are great astronomers and scientists and all of these beliefs are horribly wrong. While none of those beliefs were as obviously wrong as they are today, there was still reason to question them. The difference between their beliefs and the beliefs of others of their time is that they knew more, while the people of their time knew less. They were not smarter than anyone else.