Why do we cling to beliefs when they’re threatened by facts?

People hold beliefs for a complex variety of reasons. Some of these beliefs may be based on facts, but others may be based on ideas that can never be proved or disproven. For example, people who are against the death penalty might base their belief partly on evidence that the death penalty does not reduce violent crime (which could later be shown to be false), and partly on the notion that the death penalty violates a fundamental human right to life. The latter is an unfalsifiable belief, because it can’t be changed purely by facts.