For more on confidence, see the following link. It is not however necessary to understand this essay:
Having established that being confident is rarely a good thing, there is a relationship between confidence, reason and arrogance, that is one of if not the worst mistake people make.
Young children have to learn about reality and life in the first few years of their lives, such as the concept of conservation of matter and continuity. They also learn facts from their parents and they might think that their parents know everything. At a certain point, it is possible for children to think that they have learned enough to be able to deduce everything else. This problem could arise from two things, the first being that they might have enough information to form a seemingly sufficient base of for a “theory of everything”, or in other words they think they know the basics of all fields of knowledge. The second reason is that they have not developed their reasoning skills enough to know how to properly make conclusions using logic.
I theorise that this happens for many people at some point in the learning process, and results in the person being too confident and therefore close minded because they wrongly assume that they know enough to trust their own conclusions without checking them with other sources. This results in some conclusions they make in the future being wrong and possibly never being checked. More conclusions can then be based on these incorrect conclusions, causing a self reinforcing cycle of ignorance.
If someone does not use reason then they will most likely make incorrect conclusions. if they do not understand the necessity of scientific method they will not verify their conclusions and will not know that they are wrong. If they do not doubt their conclusions then they rely on confidence instead of reason. I propose that this is a major cause and definition of arrogance.
Arrogant people rely on faulty logic and fallacies, and instinct to make conclusions that they are confident of. Since they do not doubt themselves they rarely consider if or why they are wrong. Mistakes they make are simply assumed to be luck and they do not generally learn from them. Instead when their conclusions are correct it simply reinforces their confidence. Even worse, they can be wrong and make any excuse to convince themselves and others that they are correct.
Such people can obsessively try to convince others that they are correct, which leads to using fallacies or cheating as is commonly seen in politics. More fundamentally important, they make incorrect conclusions without knowing, and therefore make wrong decisions. A military commander that makes such decisions could get soldiers killed or lose a war. A politician that makes such decisions can oppress their people or lead a country to ruin. Less importantly, a business person could lead their company to bankruptcy.
Wrong decisions happen, but an arrogant person is more likely to make such decisions. By definition people do not want to make the wrong decision, because decisions are made in order to achieve a goal. If the decision is wrong then the person will not achieve their goal and will not get what they want. By the identity theorem, if a person wants something then they have to make a correct decisions to get it. Therefore the best way to assure that you get what you want and be successful in life is to use logic and not be confident.
While it is true that confidence allows people to achieve certain things, that is only because it allows them to perform to their potential. Being confident is a risk, because you no longer doubt yourself so you will not know if you will succeed or fail. Being unconfident will prevent you from doing things you are capable of, but neither of these options is good. The correct course to take is to be as certain as possible, and take calculated risks when needed.
Confidence is a tool; it helps you to perform certain actions you were already capable of, but it prevents you from knowing which is the correct action. Confidence leads to arrogance and creates many problems. Arrogance is possibly the worst trait humans have, and I believe it is the cause of most of humanity’s problems. Confidence is a form of faith, so instead of blindly following something, one should be rational and try to be certain instead of confident.
To know what you truly want and to be able to attain it, one must be rational and open.