Poisoning the Well
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[edit] Definition
Poisoning the well is an informal logical fallacy and specifically a form of argumentum ad hominem where a participant pre-emptively argues that another participant's statements are to be disregarded because of their personal circumstances. It is somewhat unusual in that it is used before the other participant's arguments can even be heard. In its general form, a well-poisoning argument follows this general formal
- Person A can be expected to make an argument against what I say, but
- Person A is untrustworthy.
- Therefore, whatever they say is false.
with the additional hope that person A may be dissuaded from even making the argument in the first place.
Like all genetic fallacies, this is a fallacy because the truth or falsity of the claim is not necessarily related to its origin.
[edit] Etymology
The phrase "poisoning the well" comes from the Middle Ages, where bubonic plague was spreading across Europe. A rumour arose that Jews were poisoning the wells of Christians in order to have them die of the plague.
Since no-one knew what the vectors for bubonic plague were, and since it was not possible to establish that a well had not been poisoned before an outbreak of plague, Jews were unjustly condemned without proof by their superstitious neighbours and were subject to ostracism and violence when plague broke out in a locality.
[edit] Examples
Example 1:
- Antagonist: Only someone already in league with terrorism would possibly argue against the need for these new security measures.
Example 2:
- Antagonist: Now, you will of course see Linux zombies say that their version of this program is better, but we all know the truth, don't we?
Anyone willing to debate Antagonist on either of these issues must essentially step in already branded as a supporter of terrorism or a Linux zombie, respectively.
[edit] Exceptions to the Rule
As with genetic fallacies in general, it can be difficult to determine the appropriateness of an attempt at well-poisoning. Although formally fallacious, it can often be appropriate to point out, for example, when someone has an obvious conflict of interest that might be relevant. (An obvious example is that of a jailhouse informant who has agreed to testify in exchange for additional privileges.) A person clearly motivated by self-interest cannot necessarily be trusted to tell the truth.
A key aspect of understanding any genetic fallacy is to determine whether the stated origin is, first, true (is the person really a supporter of terrorism and a Linux zombie?) and second, relevant to the question at hand.
