In psychology, confirmation bias is a phenomenon whereby, in a variety of settings, decision makers have been shown to notice more, assign more weight to, and actively seek out evidence that confirms their claims and they tend to ignore and not seek that which might discount their claims.
Confirmation bias may be the cause of self-perpetuating and self-fulfilling social beliefs.
To compensate for this natural human tendency, the scientific method is constructed so that we must try to disprove our hypotheses. See falsifiability. In addition, many legal and political systems depend on adversarial relations in order to achieve just decisions despite the biases of the parties. In these systems it is assumed that it is beyond the ability of a single human being to avoid confirmation bias, and hence the systems are in place so that different biases work against each other.
General thinkers and decision makers should consider opposing views and try to think about why they might be wrong in order to reduce overconfidence effects.