Skull & Crossbones

Poisoning the Well


The phrase "poisoning the well" ultimately alludes to the medieval European myth that the black plague was caused by Jews poisoning town wells—a myth which was used as an excuse to persecute Jews.

The phrase was first used in its relevant sense by Cardinal John Henry Newman during a controversy with Charles Kingsley:

…[W]hat I insist upon here…is this unmanly attempt of his, in his concluding pages, to cut the ground from under my feet;—to poison by anticipation the public mind against me, John Henry Newman, and to infuse into the imaginations of my readers, suspicion and mistrust of every thing that I may say in reply to him. This I call poisoning the wells.

"I am henceforth in doubt and fear," he says, "as much as any honest man can be, concerning every word Dr. Newman may write. How can I tell that I shall not be the dupe of some cunning equivocation?" …

Well, I can only say, that, if his taunt is to take effect, I am but wasting my time in saying a word in answer to his foul calumnies… We all know how our imagination runs away with us, how suddenly and at what a pace;—the saying, "Caesar's wife should not be suspected," is an instance of what I mean. The habitual prejudice, the humour of the moment, is the turning-point which leads us to read a defence in a good sense or a bad. We interpret it by our antecedent impressions. The very same sentiments, according as our jealousy is or is not awake, or our aversion stimulated, are tokens of truth or of dissimulation and pretence. There is a story of a sane person being by mistake shut up in the wards of a Lunatic Asylum, and that, when he pleaded his cause to some strangers visiting the establishment, the only remark he elicited in answer was, "How naturally he talks! you would think he was in his senses." Controversies should be decided by the reason; is it legitimate warfare to appeal to the misgivings of the public mind and to its dislikings? Any how, if Mr. Kingsley is able thus to practise upon my readers, the more I succeed, the less will be my success. … The more triumphant are my statements, the more certain will be my defeat.

Source: John Henry Newman, Apologia Pro Vita Sua

Type: Argumentum ad Hominem


I wish it were possible for men to get really emotionally involved in this question [abortion]. It is really impossible for the man, for whom it is impossible to be in this situation, to really see it from the woman's point of view. That is why I am concerned that there are not more women in this House available to speak about this from the woman's point of view.

Source: House of Commons Debates of Canada, Volume 2, November 30, 1979, p. 1920



To poison the well is to commit a pre-emptive ad hominem strike against an argumentative opponent. As with regular ad hominems, the well may be poisoned in either an abusive or circumstantial way. For instance:

  1. "Only an ignoramus would disagree with fluoridating water." (Abusive)
  2. "My opponent is a dentist, so of course he will oppose the fluoridating of water, since he will lose business." (Circumstantial)

Anyone bold enough to enter a debate which begins with a well-poisoning either steps into an insult, or an attack upon one's personal integrity. As with standard ad hominems, the debate is likely to cease to be about its nominal topic and become a debate about the arguer. However, what sets Poisoning the Well apart from the standard Ad Hominem is the fact that the poisoning is done before the opponent has a chance to make a case.


Poisoning the Well is not, strictly speaking, a logical fallacy since it is not a type of argument. Rather, it is a logical boobytrap set by the poisoner to tempt the unwary audience into committing an ad hominem fallacy. As with all forms of the ad hominem, one should keep in mind that an argument can and must stand or fall on its own, regardless of who makes it.

Analysis of the Example:

This is a common type of circumstantial poisoning of the well, which claims that men should either not make a judgment about abortion, or should keep it to themselves if they do. This illustrates the effect that poisoning the well tends to have, which is to forestall opposition in debate. It also shows the mistake underlying all poisoning of the well, since the sex of the arguer is irrelevant to the merits of the argument. No doubt one could always find a woman to advance the argument, whatever it is.



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