Troythulu’s Top 20 Logical Fallacies #16

This, the sixteenth in my series of ‘Top 20’ posts on logical errors concerns a fallacy that was only briefly touched on in my post on the ad hominem argument, (Troythulu’s Top 20 Logical Fallacies #2…)a variation of Genetic Fallacy known as Poisoning the Well, or the Circumstantial ad Hominem.

This differs from the usual form in that it can be made against both a person and an idea or belief, and is delivered before an argument is even heard. The fallacy’s name derives from the Middle Ages, when during outbreaks of plague, it was a common rumor that Jews were causing Christians to die by poisoning their wells, since the real vectors of the plague were unknown at the time.

The aim of this argument is to preemptively discredit any argument that the target makes, or to taint an idea or belief by associating that person or idea with something or someone unpleasant or distasteful, or by indicating a false conflict of interest in the target, explicitly or otherwise.

Typical is the association of the target with Hitler or Nazis, such as the phrase, “Well, the Nazis believed that too, and you don’t want to be like them do you?” In that horrible little abortion of a movie, Expelled, there was much use of this fallacy in the association of evolution with the Holocaust specifically and the Nazis in general, and the antivaccination crazies use this a lot to discredit research and scientists who contradict their position by implicating them as being involved in a Big Pharma and Big Government™ conspiracy to “hide the truth” just to fatten their own pockets.

A valid use of pointing out a possible conflict of interest regarding one’s statements is when the subject’s background, credibility and circumstances are kept in their proper context, such as a prison informant testifying in a criminal case when he has been given leniency or other favors for his testimony.