Learning Together
On a societal scale, especially in cultures and political structures shaped by European colonialism, one of the most common manifestations of systemic idea control is access to learning.
The European approach to compulsory, state-sponsored, institutional education is specifically designed to produce conformity and limit the variety of places we consider to be "acceptable" sources of learning and gaining knowledge. Only specific, sanctioned ways of "educating" are considered proper and appropriate, and often, departing from these annointed institutions is met with a combination of legal punishment and social stigma. Through cultural reinforcements, such as credentialism, we are conditioned to believe that the only way to learn is to receive knowledge directly from a recognized authority, generally in a hierarchical, structured environment.
Of course, this is a great way to ensure that huge numbers of people do not learn anything that conflicts with the interests of established power-holders - and, thereby, those interests are less likely to be threatened, and power is less likely to be redistributed.
Once we recognize this tendency, to only seek knowledge from "permitted" venues or "recognized" sources, we can begin to work against it. But it's important to do so safely, or else we may simply be caught up in misinformation or other forms of idea control that just feel different to us.
As with many aspects of oppression, this idea-imprisonment system can be overcome by working together. If we find a set of people we're willing to learn with, we can begin to share ideas, explore new understandings, and even invent entire new ways of living and being - together.
And in point of fact, every instance of massive, societal change we can study includes examples of people doing exactly that: deciding that the ideas we've been handed, by the systems and powers around us, are not acceptable any more, and committing to learning in new ways.