Godwin's Law

According to Godwin's Law,
"As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one." A variation of this is the debate fallacy sometimes called reductio ad Hitlerem. The idea is that the debater loses the argument if that debater invokes the World War II period generally and Nazis, fascists, or Hitler specifically. I think the reason for this comes from the exceptional circumstances that gave rise to that period. Thus, the use of features from that time period are suspect as analogies that illuminate or support a point of view.