A useful dividing line to determine sanity vs. Insanity is whether the individual, or the group, Strongly tends to rigidly bias toward their own view, their own set of information, over the information and or views outside of themself. The great Alfred Adler referred to this in terms of private logic vs common sense, as I recall. Or maybe he said private logic vs public logic. An intrinsic preference for my Truth, versus the truth. An example that occurs to me is David Nash, depicted accurately I suspect in the movie, A Beautiful Mind. David was a brilliant professor at Princeton. He had an extremely active mind. Created understandings of the world which he found compelling. They led to him to view that his children and wife were mortal enemies and on the verge of acting on that view he thought of something new. Maybe just because the views in his mind were detailed and compelling, maybe they weren't correct. He spent the rest of his life acting on that later conception, that not everything in his mind was correct, and he tried very hard to understand the truth as opposed to his own truth. Much more importantly there are few on the left in this country, there are few on the right in this country , that are much interested in the truth available to us all. They are interested in the portion of the truth that their respective groups find comfortable and are opposed to understanding the more comprehensive truth that could embrace all parties.