In liberal democratic societies, it has long been understood that the use of force to control the population is generally not a viable option. Therefore, controlling what people think is critical. Thus, an elaborate system of propaganda is needed. For that system to be effective it must appear invisible. In totalitarian states there is no ambiguity. Citizens know they are getting the party line. But in countries like the U.S., where ownership is private and formal censorship is absent, there is an appearance of a free flow of information. However, that flow passes through successive filters, leaving only the cleansed residue fit to print.