Cognitive Dissonance (Festinger, 1957) is a theory which explains the feeling which can occur when two opposing opinions or beliefs are held simultaneously. For example, if you need to work with a computer to make your living, but your PC is running slowly then you may consider doing a scan disc/defrag etc. But this means that you can’t add any value and will be waiting while the essential maintenance is carried out. So what do you do? You have a goal to meet, taking time away from your work task will mean missing short term targets, but if you do the maintenance your productivity will increase. Productivity or maintenance, long term or short term? Your brain starts to fry. What should you do? Is the maintenance an excuse to slack off? Is working through with a slow PC just pig headed? This is cognitive dissonance.
Cognitive dissonance also explains why people fail to change and become stagnated in their thinking. When a firmly held belief is challenged with new facts or information, the uncomfortable feeling caused by cognitive dissonance is often such that the first instinct is to get rid of the pain by rationalising, or reframing to maintain the old belief.