In many different settings, on both sides of any issue, I have often heard the claim that "The fact you're angry about this indicates that you're wrong", in some form or other, perhaps not that exact wording. This is a logical fallacy. There are actually many reasons that a person could become angry while arguing, and being wrong isn't the only one. But the reason that I would like to focus on in this post is a term called "cognitive dissonance."
Cognitive dissonance is the state of experiencing two dissonant, or contradictory, ideas (or cognitions) at the same time. This is actually a very big field of study in psychology. For example, as a gay teenager, I felt cognitive dissonance in high school when I noticed feelings of attractions for other boys. I was raised to believe that homosexuality is bad and that men should date and marry women, not other men. Therefore, feelings of attraction toward males were dissonant with what I believed concerning homosexuality. When cognitive dissonance is experienced, the brain has several ways of coping with the dissonant ideas. The way I dealt with the feelings I had for other boys was to deny them. I reasoned to myself that what I was feeling was not a sexual attraction, but that it was a friendly attraction--a strong desire to be friends with the boy, rather than a desire to be intimate with him. When I found myself looking at gay pornography online, I denied that as well and explained it as merely the fascination with my own genitals and the desire to have bigger genitals, and not necessarily that I was gay.
One of the main ways that the brain reacts in response to cognitive dissonance is defensiveness and anger. The brain interprets the new, contradictory idea as a threat and employs mechanisms to defend against it. The person feeling the dissonance may become angry. During arguments with other people, I have noticed this happening in myself and with the person I was arguing with.
Another example would be a Mormon who comes across "anti-Mormon" literature. A member of the LDS church has been taught that in the Spring of 1820, Joseph Smith Jr. had a vision in a grove of trees where he saw two beings--God, the Father, and Jesus Christ, the Son. Upon reading through Joseph Smith's writings, one learns that he gave multiple accounts of the event, many of which contradict each other. One describes only one person appearing, another says that a host of angels appeared. When a Mormon first encounters this information, cognitive dissonance is experienced. At this point, many different reactions could occur. One could deny the new information and dismiss it as "anti-Mormon" and therefore invalid. (Conrad has a brother who says that anything that isn't published on LDS.org isn't true.) One could explain the discrepancy by suggesting that people do not always recall events precisely as they happened, and that it was likely that he did have the vision but remembered it differently with each telling. And when two people are discussing the matter, one person becoming angry at the other person contradicting em is not at all uncommon or unexpected.
One big problem with cognitive dissonance is that it can happen at any time to anyone. It happened to the man in the video when he was test flying an airplane and his own senses disagreed with what the instruments were telling him. In his case, what he believed was false and what the instruments were telling him was true. But cognitive dissonance can also occur when what one believes is true and the contradictory claim is the false one. Thus, a person is experiencing cognitive dissonance does not logically imply that the person is incorrect.
But the very fact that the brain will attempt to protect itself from dissonant ideas is why it is so vital for us each to be open-minded to differing viewpoints and to consider things from a different angle. When two people perform the same experiment and obtain corroborating results, the likelihood that the conclusion drawn is true is greater than when the two experimenters obtain differing results. If we would like to understand what reality is and overcome the bias biologically built in to our own brains, we must be willing to accept dissonant ideas and to discuss them with other people so as to reconcile them with reality.
One of the greatest dangers of religion is that doubting is declared to be a sin. To question authority is to apostatize and blaspheme. This teaching actually amplifies the negative reaction that occurs when cognitive dissonance inevitably occurs. In order to fully understand our surroundings, it is absolutely imperative that we doubt what we are told, that we doubt what our senses tell us, and that we are willing to listen to ideas that contradict our own.