When you disagree with someone, and assuming that the subject of disagreement is not one that can be scientifically verified one way or the other, if you cannot find one thing about the other person’s argument that you admire, if you cannot find one thing about your own argument that causes you concern, then you are an extremist. If you do not doubt a little of your own infallibility, then you are an extremist. The person who is certainly crazy is the person who thinks that their way is the only way. Extremists are certainly crazy, and not in a good way.
A Practical Definition of “Extremist”