fallacy

play
noun fal·la·cy \ˈfa-lə-sē\

Definition of fallacy

plural

fallacies

  1. 1 a obsolete :  guile, trickery b :  deceptive appearance :  deception

  2. 2 a :  a false or mistaken idea <popular fallacies> b :  erroneous character :  erroneousness

  3. 3 :  an often plausible argument using false or invalid inference

Examples of fallacy in a sentence

  1. The fallacy of their ideas about medicine soon became apparent.

  2. <the once-common fallacy that girls just weren't any good at math>

Did You Know?

Philosophers are constantly using the word fallacy. For them, a fallacy is reasoning that comes to a conclusion without the evidence to support it. This may have to do with pure logic, with the assumptions that the argument is based on, or with the way words are used, especially if they don't keep exactly the same meaning throughout the argument. There are many classic fallacies that occur again and again through the centuries and everywhere in the world. You may have heard of such fallacies as the "ad hominem" fallacy, the "question-begging" fallacy, the "straw man" fallacy, the "slippery slope" fallacy, the "gambler's" fallacy, or the "red herring" fallacy. Look them up and see if you've ever been guilty of any of them.

Origin and Etymology of fallacy

Latin fallacia, from fallac-, fallax deceitful, from fallere to deceive


First Known Use: 14th century


FALLACY Defined for English Language Learners

fallacy

play
noun fal·la·cy \ˈfa-lə-sē\

Definition of fallacy for English Language Learners

  • : a wrong belief : a false or mistaken idea

  • : the quality of being false or wrong


FALLACY Defined for Kids

fallacy

play
noun fal·la·cy \ˈfa-lə-sē\

Definition of fallacy for Students

plural

fallacies

  1. 1 :  a false or mistaken idea

  2. 2 :  false reasoning



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