One single proof
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|Not just a river in Egypt|
"One single proof" 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.
Examples of the technique include
- In Holocaust denial, the insistence that the history defender produce a written order from Adolf Hitler ordering the extermination of the Jews, despite the fact that Hitler's desire to eliminate Jewry was fairly well-known without an explicit order being issued;
- Among Creationists, demanding one single transitional fossil, usually according to a Creationist definition of the term that is not recognized in scientific circles;
- Among tax protesters in the United States, demanding that the government show the protesters the law authorizing the income tax, while denying that the 16th Amendment to the Constitution (which they claim was never properly ratified) and Title 26 (the Federal tax code) constitute sufficient authorization in the eyes of the US Federal courts.
- 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.
- Global warming deniers will sometimes ask for "one single study" that shows CO2 is a pollutant (which is in not even wrong territory). Another angle, as Roy Spencer takes, is to ask this: "Show me one peer-reviewed paper that has ruled out natural, internal climate cycles as the cause of most of the recent warming in the thermometer record."
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.
 See also
| Articles about logical fallacies|
|Affirming the consequent||Denying the antecedent|
One single proof
|Fallacious argument styles|