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| {{Merge to|Hasty generalization|date=November 2010}}
| | Hi there. My name is Garland although it is not the name on my beginning certificate. One of his preferred hobbies is taking part in crochet but he hasn't made a dime with it. Years ago we moved to Kansas. His working day occupation is a monetary officer but he plans on altering it.<br><br>Also visit my web-site; [http://Www.evil-Esports.de/cs/index.php?mod=users&action=view&id=5958 extended auto warranty] |
| {{Refimprove|date=November 2006}}
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| '''Proof by example''' (also known as '''inappropriate generalization''') is a [[Informal fallacy|logical fallacy]] whereby one or more examples are claimed as "proof" for a more general statement.<ref>http://www.auburn.edu/~marchjl/fallacies.htm</ref>
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| This fallacy has the following structure, and [[argument form]]:
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| Structure:
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| :I know that X is such.
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| :Therefore, anything related to X is also such.
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| [[Argument form]]:
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| :I know that x, which is a member of group X, has the property P.
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| :Therefore, all other elements of X have the property P.
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| The following example demonstrates why this is a logical fallacy:
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| : I've seen a person shoot someone dead.
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| : Therefore, all people are murderers.
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| The flaw in this argument is very evident, but arguments of the same form can sometimes seem somewhat convincing, as in the following example:
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| :I've seen Gypsies steal. So, Gypsies must be thieves.
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| ==When valid==
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| However, argument by example is valid when it leads from a singular premise to an ''existential'' conclusion. For example:
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| :Socrates is wise.
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| :Therefore, someone is wise.
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| (or)
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| :I've seen a person steal.
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| :Therefore, people can steal.
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| This is an informal version of the logical rule known as [[List_of_rules_of_inference#Rules_of_classical_predicate_calculus|existential introduction]] (also known as ''particularisation'' or ''existential generalization'').
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| Formally
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| ;Existential Introduction:
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| : <math>\underline{\varphi(\beta / \alpha)}\,\!</math>
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| : <math>\exists \alpha\, \varphi\,\!</math> | |
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| ==See also==
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| *[[Modus ponens]]
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| *[[Affirming the consequent]]
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| *[[Inductive reasoning]]
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| *[[Bayesian probability]]
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| *[[Proof by construction]]
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| *[[Anecdotal evidence]]
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| *[[Counterexample]]
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| ==References== | |
| <references/>
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| {{Formal Fallacy}}
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| {{DEFAULTSORT:Proof By Example}}
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| [[Category:Quantificational fallacies]]
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