There are two contexts for the notion of "crazy." The first refers to a person who has sensory hallucinations and/or concretely, patently untrue delusions (e.g., the newscaster on the television is actually talking to me, personally). The second notion of "crazy" refers to someone whose viewpoint, in some context, is different from the usual or the customary. The premise of this definition of "crazy" is that "sanity" is defined by the usual, i.e. that which is usually thought to be true by most people. By this definition of sanity, you're sane if you think as most people think; and you're (at best) less than sane if you dissent from the majority. This is what's known as social metaphysics, the view that reality is determined not by facts or evidence, but by what most people think.

While it is true that most people usually have a good reason for what they think, and most people often are right about many things, it's equally true that most people are sometimes totally wrong -- even profoundly wrong. This is all the proof you need that "most people" cannot be the standard of truth, and likewise cannot be the standard of sanity or insanity. Some of the greatest innovators of history have been called crazy at the time, and later (often after their deaths) hailed as geniuses whose discoveries or ideas changed life for the better. It's little wonder that the notion of "crazy" holds such appeal to dictators or anyone else that seeks control. It's called the argument from intimidation. "If I call you crazy, then you'll believe me, and you will then think or do as I say." That's why it's important to know that truth resides "out there" in reality, and not necessarily in the minds of most people. You absolutely must have proof that something is true. But if you do indeed have that proof, all the dissenting voices in the world will not change your mind.