Cognitive dissonance is a psychological phenomenon which refers to the discomfort felt at a discrepancy between what you already know or believe, and new information or interpretation.
It therefore occurs when there is a need to accommodate new ideas, and it may be necessary for it to develop so that we become open to them.
This is explained in a book called Descartes' Error by Antonio Damasio. He explains that the lack of ability for US citizens to actually see reality is based on a problem of physical pain in the brain that occurs when someone is faced with new learning that contradicts prior accepted knowledge.
Dr. Damasio says that mind functions by way of a network of neural synapses in the brain that become literally destroyed when confronted by new knowledge. They have to be literally broken to bits and rebuilt, and this destruction causes actual physical pain to the individual.
We as a society now have become pain-adverse to the point that we would rather actually die than learn something new, and endure the actual pain of new learning. Therefore we are now at absolute mortal risk because of our inability to make life saving painful judgments.