Fallacy

A fallacy is the use of <a href="/facts/Validity_(logic)/oMGkywGC">invalid</a> or otherwise faulty <a href="/facts/Reason/tcBImN8J">reasoning</a> in the construction of an <a href="/facts/Argument/1K1e3Xg4">argument</a> that may appear to be well-reasoned if unnoticed. The term was introduced in the Western intellectual tradition by the <a href="/facts/Aristotle/U2bDlBFW">Aristotelian</a> <a href="/facts/Sophistical_Refutations/sqKIC5fw">De Sophisticis Elenchis</a>. 
Fallacies may be committed intentionally to <a href="/facts/Psychological_manipulation/RLqHuGzV">manipulate</a> or <a href="/facts/Persuasion/kWj4ff3w">persuade</a> by <a href="/facts/Deception/ADLUf5ts">deception</a>, unintentionally because of human limitations such as <a href="/facts/Carelessness/LmL7lmsK">carelessness</a>, <a href="/facts/Biases_in_judgment_and_decision_making/1d1rwe2N">cognitive or social biases</a> and <a href="/facts/Ignorance/FYCAAA79">ignorance</a>, or potentially due to the limitations of language and understanding of language. These delineations include not only the ignorance of the right <a href="/facts/Psychology_of_reasoning/czbjIzXM">reasoning standard</a> but also the ignorance of relevant properties of the <a href="/facts/Context_(language_use)/eJM44o7x">context</a>. For instance, the <a href="/facts/Soundness/ndpamd2A">soundness</a> of <a href="/facts/Legal_argument/9oaSBJSo">legal arguments</a> depends on the context in which they are made.
Fallacies are commonly divided into "formal" and "informal". A <a href="/facts/Formal_fallacy/1c3P1BEH">formal fallacy</a> is a flaw in the structure of a <a href="/facts/Deductive_reasoning/HadA1zWS">deductive</a> <a href="/facts/Logical_argument/1K1e3Xg4">argument</a> that renders the argument invalid, while an <a href="/facts/Informal_fallacy/MfICjFRF">informal fallacy</a> originates in an error in reasoning other than an improper <a href="/facts/Logical_form/foVBtMX4">logical form</a>. Arguments containing informal fallacies may be formally <a href="/facts/Validity_(logic)/oMGkywGC">valid</a>, but still fallacious.
A special case is a <a href="/facts/Mathematical_fallacy/tUIV7DQV">mathematical fallacy</a>, an intentionally invalid <a href="/facts/Mathematical_proof/7ECDrU80">mathematical proof</a> with a concealed, or subtle, error. Mathematical fallacies are typically crafted and exhibited for educational purposes, usually taking the form of false proofs of obvious <a href="/facts/Contradiction/PQHH5a2J">contradictions</a>.

Fallacy open-in-new

Fallacy