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One Single Proof

September 24th, 2009

One Single Proof

classification : informal – rhetorical technique

Is a deceptive rhetorical flourish used primarily by denialists designed to apparently negate a preponderance of circumstantial evidence by claiming that without a specific key proof, the whole argument is invalid.


The effectiveness of the technique is dependent on a sort of distortion of Occam’s razor whereby any evidence that does not provide the whole answer is ignored.

The fallacy often rests on the idea that without a particular key bit of information, the entire system will fall apart. While this is sometimes the case, particularly when dealing with mathematical proofs, forensic arguments often make use of large quantities of circumstantial evidence in such a way as to point directly to a cause without a single smoking gun


Among deniers of the harmful effects of tobacco smoking (active and passive), demanding that public health authorities produce the death certificate of one person who died as a consequence of exposure to secondhand smoke, and, in the absence of such a death certificate, concluding that such exposure is innocuous.

Other Names

Smoking gun
Extraordinary claims require extraordinary evidence

Note: Rhetorical techniques such as 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. An argument must stand or fall on its own, regardless of who makes it.

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Categories: Logic