Difference between revisions of "Valid argument"

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An argument is '''valid''' when it contains no logical fallacies. Such arguments are not necessarily [[sound argument|sound]], because the premises may be false. For instance, the following syllogism is valid but has a false conclusion:
"Valid" is used by logicians to describe an argument or syllogism in which no logical fallacies are made. This is not necessarily [[Sound logic]], because the premises may be false. For instance, the following syllogism is valid but has a false conclusion:
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* All animals are dogs. (False premise/All A are B.)
 
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* All dogs are terriers. (False premise/All B are C.)
All animals are dogs. (False premise/All A are B.)
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* Thereforse, all animals are terriers. (False conclusion: not all animals are terriers. Valid logic: If all A are B, and all B are C, then all A are C.)
All dogs are terriers. (False premise/All B are C.)
 
Thereforse, all animals are terriers. (False conclusion: not all animals are terriers. Valid logic: If all A are B, and all B are C, then all A are C.)
 
  
 
==Blog posts==
 
==Blog posts==
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==See also==
 
==See also==
  
*[[Sound logic]]
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*[[Sound argument]]
  
 
[[Category:Concepts]]
 
[[Category:Concepts]]
  
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Revision as of 07:06, 23 January 2011

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An argument is valid when it contains no logical fallacies. Such arguments are not necessarily sound, because the premises may be false. For instance, the following syllogism is valid but has a false conclusion:

  • All animals are dogs. (False premise/All A are B.)
  • All dogs are terriers. (False premise/All B are C.)
  • Thereforse, all animals are terriers. (False conclusion: not all animals are terriers. Valid logic: If all A are B, and all B are C, then all A are C.)

Blog posts

  • [1] (tangentially related)

See also