The original role of propaganda was to persuade people to believe in and support an idea or policy they may not otherwise accept on their initial appraisal of it.. Propaganda was, more or less, a technique of persuasion, usually appealing to emotions and psychological inclinations more than rational thought.
Today, I believe, propaganda aims to deliberately create cognitive dissonance among the population. Cognitive dissonance is a type of mental disorder in which a person holds inconsistent or contradictory thoughts and attitudes, particularly relating to their own behavior and the observable reality around them.
Such a state of mental confusion is useful for power because the reflexive reaction of most people who experience cognitive dissonance is to simply suspend rational analysis and retreat into a kind of intellectual fetal position in which they do not try to understand anything at all. They become incredibly easy to control and suppress because they have, in fact, suppressed themselves.
It causes people to no longer reconcile their actions with their beliefs.
This type of psychological torture is actually one of the techniques used in interrogation. The idea is to disorient the detainee, confuse him, subvert his judgement, and completely short-circuit his ability to think.
You can notice, for example, in popular media the juxtaposition of extremely grave matters alongside ridiculously trivial information. A story about a massacre may be followed by a story about an actress’s diet. Or you may see in the margins of an article online about famine, pictures of celebrities who have had plastic surgery.
This type of inconsistency in subject matter interferes with the mind’s ability to process serious information in a thoughtful way. Everything becomes trivial.
This is confusing and disorienting because we know that serious issues are serious, but our thought process is sabotaged, our judgement interrupted. Over time, and in the age of the “24 hour news cycle” and online “information overload” this consistent infliction of inconsistency creates intellectual regression.