Let’s look at an oppressive society. In this environment, if you don’t think like what the government tells you to think, you must be evil and should be shut up. Controlling thoughts is a deeply rooted element of this society, which is the type of society that will never go anywhere. That kind of thinking is fascism. Children are raised not to have critical thinking and own ideas, but they are told to obey the authority, at home, at school, and to the men in charge. The seeds are planted in these young minds to never question the power that be.
In this society, discussions and arguments are just facade. People are limited in what they are able say. Reality is contorted, and if one ever questions the status quo, he is branded a bad person.
Brainwashing propaganda by the authority is one of the most serious problem in such society. It conditions the population to think alike and forms a mob mentality that is highly hostile to those with courage to present their criticisms the system. The propaganda allows the state of the oppressed society and is the reason why the dictators can illegally take control of it.
No society should operate this way—the one that wants to progress, at least. Oppression of free speech plants bad seeds and impedes growth. There should exist public arenas where people are free to share different ideas without fear of prosecution, both legal and social.