Thought Control
Thought Control was a hot topic in the mid 20th century, due to the legacy of mass socialist movements such as Nazism and Communism, and to the writing of important dystopian novels, such as Nineteen Eighty-Four, Brave New World, Animal Farm, Fahrenheit 451, Lord of the Flies, and Catch 22. It's related to terms like "brain washing", "thought police" and even "nudge". See Brainwashing.
Actual thought control requires such things as (1) redefining the meanings of key words, like "marriage" and "family" and "freedom" (especially "reproductive freedom") and "diversity" and "scientific" and "progressive" and "reform", (2) rewriting history books and tearing down/removing statues and other artifacts of the past, (3) revamping school curricula and school discipline, (4) controlling who gets into the country and who doesn't, (5) controlling who gets arms and who doesn't (botched "Operation Fast and Furious", anyone?), (6) deciding which foreign governments get what aid and with what strings attached, (7) deciding what events (such as mass demonstrations, shootings or other violent acts, political polls or rallies...) get covered and how they are covered, (8) deciding who gets into the military or gets promoted and why, (9) deciding which "facts" are checked and which aren't, and how, (10) deciding which statistics are accurate/meaningful/important and which are not, (11) deciding which political groups get tax exemption and which do not, (12) deciding which teachers/professors get hired and which do not, (13) who gets marginalized with pejoratives and who doesn't, (14) who is held accountable for criminal activity and who isn't, etc., etc., etc.
Thought control is an increasingly important political tool throughout the world, thanks in part to the increasingly pervasive role of electronic media and the rapid formation of mass movements in virtually every domain of human activity.
As any engineer of control systems can tell you, control is not enough, observation is also crucially important. See observability and controllability. Recognition of this has led to the development of such major postmodern marketing phenomena as Google, FaceBook and Amazon. The mid-twentieth century phenomenon of "subliminal advertising" and the post-modern phenomenon of "spin control" also are important.
As a result, self-possession, self-control, self-discipline, self-awareness and independence of thought are increasingly challenging virtues to cultivate.