Scott Bailey has engaged in a debate (on Jim West's blog) that aptly illustrates the futility of arguing with individuals who are devoted to a fringe theory in spite of its general lack of acceptance by the academic community. These individuals are often called cranks or crackpots, and there's even a Wikipedia entry devoted to the phenomenon.
"Crank" is a pejorative term for a person who holds a belief that a vast majority of their contemporaries consider false. A "cranky" belief is so wildly at variance with commonly accepted truth as to be ludicrous, and arguing with cranks is useless, because they will invariably dismiss all evidence or arguments which contradict their unconventional beliefs.I want to draw Scott's attention to the highlighted phrase above - "arguing with cranks is useless." His interaction quickly descended into veiled insults and blatant condescension on both sides. I used to engage crackpots in debates (attempting to prove to the KJV only people that they were insane, for example). It was pointless and I got no where. Now I avoid direct engagement if possible. It serves no purpose. I now follow the "don't dignify it with a response" rule. And no, this is not a response. It is a reaction to the debate, not a direct response. (That's why I'm not highlighting what was being debated.)
Common synonyms for "crank" include kook and crackpot. Crank differs from fanatic in that the subject of the fanatic's obsession is either not necessarily widely regarded as wrong or not necessarily a "fringe" belief. Similarly, the word quack is reserved for someone who promotes a medical remedy or practice that is widely considered to be ineffective. Crank may also refer to an ill-tempered individual or one who is in a bad mood, but that usage is not the subject of this article. (emphasis added)