The creation of rationale to alleviate psychological discomfort caused by the evidence presented by facts that contradict beliefs and ideas that the individual is reluctant to reevaluate.
The discomfort felt by wanting or striving to maintain a certain belief and contrary evidence challenging that belief. Part of the discomfort arising from the emotional and psychological investment in the belief and the consequences of having to reevaluate that belief, and manage the uncomfortable feelings that a dynamic without this belief entails.
Some examples being:
Having strongly held religious beliefs and a scientific discovery refuting the corner stone of that religion. So creating a rationale that the discovery is bogus or flawed, rather than face the possibility that the religious doctrine is flawed.
A spouse coming home late, using work as an excuse. Then discovering the spouse wasn't working, so rather than face the consequences of the spouse lying, to either believe further lies built upon this given by the spouse (against better judgement) or to invent reasons that reconcile why the spouse took so long to return from work, and deny the possibility that the spouse was doing something that could threaten the relationship.
The process of maintaining belief in the constructed rational causes psychological unease and blocks the process of critical thought.