In university sociology classes, we studied propaganda methods for manipulating public opinion. The value of studying these techniques was to prepare us not to be misled by bad actors such as the Nazis of previous decades or the Soviets in our day, the 1960s.
Some of the techniques are as follows:
The Big Lie. It seems counter-intuitive, but people are as likely to believe a big lie as a small one, especially if it makes them feel better about themselves. The Nazi big lie, for example, was that all of their nation’s troubles were because of Jews.
The Repeated Lie. When a lie is repeated long enough, especially after it has been discredited, people tend to believe it must be true. The evidence against it must have been false, people figure, or they could not still be hearing it stated so openly.
The Straw Man. A leader creates a problem he can easily solve in order to show his genius. Or, better yet, he sets up an enemy he can easily defeat in order to gain his followers’ gratitude and adoration.
Gaslighting. Various misinformation and disinformation and constant denials are used to cause people to doubt what is right before their eyes.
The Band Wagon. Hype, such as TV ads, exaggerated boasting, exciting rallies, and so on, create the feeling that a particular viewpoint is winning the day, and everyone should get on board with it right away or be left behind.
There are other techniques, but these are the ones I remember after fifty-plus years. Easy access to social media around the world has multiplied the effectiveness of such techniques exponentially. When paired with Breitbart and Cambridge Analytica's mining of our personal data, including our preferences and attitudes, it becomes clear how vulnerable we are. Self-awareness is critical.