Consensual Reality, the idea that reality is somehow the aggregate of individual opinions, where we agree we define reality. If an individual goes against the collective agreement they are generally presumed to be either enlightened, or insane/mad. Psychology and Psychiatry implicitly depend upon this model. Where cultures and nations differ in Consensual Reality we often reach "agreement" through such means as war, or cultural imperialism, having triumphed and persuaded our new subjects we've expanded our "Consensual Reality" and use our victory as proof of the validity of our system...
An interesting idea, in that it implies that there is no one objective reality, rather reality is fluid and changing with the agreed perceptions of the viewers.
And, like any conclusion arrived at through mass experience or opinion or perception, it's entirely likely / probably / Certainly even wrong. Consider all the beliefs humanity has had in the past, and consider how few hold up today, we feel free to mock them, deride them, yet in our shared belief system or agreement as to what constitutes reality we are making the exact same errors...
Curious, too, how fluidly we bring others on board our reality - whether it be liquor or drugs, those who don't partake are never part of the shared experience of those who do ... for this they are labelled as "Sticks in the mud" or "Party Poopers", because they are not sharing in the same state of mind. Even when, for example the midst of a coke/ether/LSD binge the shared reality is entirely questionable if not obviously wrong. For those groups not imbibing there exists a very discernible line between the shared reality of one group and the shared reality of another.
And note how well media, news, advertising and corporations shape and define our reality, their perpetually broadcast messages creating hidden agreements and alternate realities that go unquestioned...
A gold mine of thought there. A link to a better explanation of the notion of Consensual Reality below.