ProofByUtility is another way of saying ItWorks! (At least most of the time). The proof is that It is used, by many who find it useful. See MicrosoftWindows and LinuxOperatingSystem. The proof is not that it is correct, precise, foolproof or bugproof, but that it is useful.

ProofByUtility is a classic non-proof, wherein someone says "Look, there are '''''so''''' many useful consequences of this that it simply '''''must''''' be true."

Otherwise known as wishful thinking.

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''This implies that it has been tried. The name ProofByUtility does not really fit with the connotation of WishfulThinking. How about ProofByAssumedUtility?''

Not really. If it were true, it would be really useful (so it's not that the utility is being assumed - the utility is evident, it's the truth that's being assumed). AssumedTruthFromUtility would be more accurate, but takes the humor out of it - it's supposed to resemble real proof methods like ProofByInduction. It's one of a set of fake "proof" methods (see the entire page at http://www.bluemoon.net/~watson/proof.htm)

''I see that it fits the format of the page you mentioned, but I was expecting it to fit the more formal format used on the FallaciousArgument page. Actually, the point I'm trying to raise is simply whether or not the utility has actually been measured, or is just a guess. If it has actually been measured, then yes, you have proved that it is correct because you have shown that it is actually useful. (This is assuming a PhilosophyOfPragmatism.) If it has not been measured, then it most definitely is wishful thinking and one of the FallaciousArgument''''''s. However, the name 'ProofByUtility' doesn't fit well with the FallaciousArgument page because it doesn't highlight the question of whether the utility has actually been measured.''

I hadn't read that page (and hadn't expected this page to be taken so seriously)
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There seem to be 2 different fallacies here:

* wishful thinking: Although no one has ever tried X, X must be true because it would be so very useful. ("This new subroutine I just finished typing in will fix your problem.")
* argument by popularity: Many people tried X and found it to work. Therefore X must be the best way of doing it. ("Visual Basic is superior to Lisp."; "PersonalDigitalAssistant is superior to PersonalAnalogDevice.")
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It seems to me that the argument presented introduces another proof: "ProofByMeasurement?". The implication is that it can only be proven by measurement. This is fine for such things as a "Too tall" proof (where a book is to be placed on a proper bookshelf [one tall enough] But not all things to be proven can be objectively measured, or they have interoperative dependencies (depending on more than one thing, because they are a part of a system). Example: prove that my thermostat "works". 
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Related to FallaciousArgument, LocalMaximum, ManyThingsDoNotRequireProof

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CategoryProof