It's called 'cognitive dissonance': when two 'cognitions' (ideas, or feelings, or facts) contradict (are in 'dissonance'), we feel uneasy, so we resolve the sit

It's called 'cognitive dissonance': when two 'cognitions' (ideas, or feelings, or facts) contradict (are in 'dissonance'), we feel uneasy, so we resolve the situation by suppressing one cognition. To do so, we usually need to resort to convincing ourselves of what are really logical fallacies or sophisms. E.g. cognition 1: I only buy from companies that are good; cognition two: company I bought from did something bad. Fact is I have something from the company, so the only resolution is: accusation against company is false. An easy way to convince yourself of something that is not rationally true is by evangelism: telling others that yes, this is the best way or greatest thing. The more you repeat it, the more you will believe it yourself. This phenomenon is especially strong with something that people derive identity from, like religion or (especially for juveniles who have not yet developed a complete identity) psychological feelings of affiliation with subcultures revolving around a certain music genre or goods that project a certain lifestyle to others (designers goods like expensive hand bags, shoes or iPhones).