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Poisoning the Well

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(also known as: discrediting, smear tactics)

Description: To commit a preemptive ad hominem attack against an opponent.  That is, to prime the audience with adverse information about the opponent from the start, in an attempt to make your claim more acceptable or discount the credibility of your opponent’s claim.

Logical Form:

Adverse information (be it true or false) about person 1 is presented.

Therefore, the claim(s) of person 1 will be false.

Example #1:

Tim: Boss, you heard my side of the story why I think Bill should be fired and not me.  Now, I am sure Bill is going to come to you with some pathetic attempt to weasel out of this lie that he has created.

Explanation: Tim is poisoning the well by priming his boss by attacking Bill’s character, and setting up any defense Bill might present as “pathetic”.  Tim is committing the fallacy here, but if the boss were to accept Tim’s advice about Bill, she, too, would be committing the fallacy.

Example #2:

I hope I presented my argument clearly.  Now, my opponent will attempt to refute my argument by his own fallacious, incoherent, illogical version of history.

Explanation: Not a very nice setup for the opponent.  As an audience member, if you allow any of this “poison” to affect how you evaluate the opponent’s argument, you are guilty of fallacious reasoning.

Exception: Remember that if a person states facts relevant to the argument, it is not an ad hominem attack.  In the first example, if the other “poison” were left out, no fallacy would be committed.

Tim: Boss, you heard my side of the story why I think Bill should be fired and not me.  Now, I am sure Bill is going to come to you with his side of the story, but please keep in mind that we have two witnesses to the event who both agree that Bill was the one who told the client that she had ugly children.


Walton, D. (1998). Ad Hominem Arguments. University of Alabama Press.

Registered User Comments

Joe Walker
Saturday, January 21, 2017 - 01:42:13 PM
I think that the Media and Trump do this to each other all of time. To avoid being a part of the fallacy, I am suppose to disregard the derogatory language that they use against each other. But, what if one side where true but the other side was false, how would handle that be handled.

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Bo Bennett, PhD
Saturday, January 21, 2017 - 02:53:52 PM
The fallacy is when the crap being said about the person is unrelated to what the person is claiming. So if the media says Trump is a lair, the you don't believe when he tells you X because you recall what you he media said about him, that would be fallacious. There is some nuance here... reputations can rightly influence perceptions. But to make a definitive claim that Trump has lied because the media reminded us of his past lies, is fallacious.

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