People tend to have contempt for ideas that they disagree with. What’s worse is the possibility that some people, when presented with information that goes against their beliefs, may not only snub their challengers, but also double down on their original viewpoints. Cognitive psychologists call this the backfire effect.
For instance, voters have been shown to judge the political candidate they support even more favorably after the candidate is attacked by the other party. In the same way, parents opposed to vaccinations have been shown to become more convinced of their alleged apprehension that vaccination causes autism after reviewing studies showing that vaccinating their kids is the best course of action.
The backfire effect explains why, when people argue against conflicting information strongly enough, they wind up with more supportive arguments for their cause, which further aligns them with their preexisting positions.
The backfire effect is related to confirmation bias—the rampant propensity to seek, interpret, synthesize, and recall information in a way that substantiates one’s preconceptions. For instance, when people read an article that describes both sides of an issue, they tend to select that side that they happen to agree with—thus reinforcing their viewpoints.
See also: the phenomenon of group polarization explains why people who share opinions and beliefs get together in groups, they tend to be even more persuaded in their beliefs.