fallacy, formal and informal
- fallacy, formal and informal
-
In philosophy, reasoning that fails to establish its conclusion because of deficiencies in form or wording.
Formal fallacies are types of deductive argument that instantiate an invalid inference pattern (
see deduction;
validity);
an example is "
affirming the consequent: If A then B;
B;
therefore,
A."
Informal fallacies are types of inductive argument the premises of which fail to establish the conclusion because of their content.
There are many kinds of informal fallacy;
examples include argumentum ad hominem ("
argument against the man"),
which consists of attacking the arguer instead of his argument;
the fallacy of false cause,
which consists of arguing from the premise that one event precedes another to the conclusion that the first event is the cause of the second;
the fallacy of composition,
which consists of arguing from the premise that a part of a thing has a certain property to the conclusion that the thing itself has that property;
and the fallacy of equivocation,
which consists of arguing from a premise in which a term is used in one sense to a conclusion in which the term is used in another sense.
* * *
Universalium.
2010.
Look at other dictionaries:
Informal logic — (or, occasionally, non formal logic) is the study of arguments as presented in ordinary language, as contrasted with the presentations of arguments in an artificial, formal, or technical language (see formal logic ). Informal logic emerged in… … Wikipedia
Formal fallacy — In philosophy, a formal fallacy or a logical fallacy is a pattern of reasoning which is always wrong. This is due to a flaw in the structure of the argument which renders the argument invalid. A formal fallacy is contrasted with an informal… … Wikipedia
Fallacy — In logic and rhetoric, a fallacy is usually incorrect argumentation in reasoning resulting in a misconception or presumption. By accident or design, fallacies may exploit emotional triggers in the listener or interlocutor (appeal to emotion), or… … Wikipedia
Formal proof — See also: mathematical proof, proof theory, and axiomatic system A formal proof or derivation is a finite sequence of sentences (called well formed formulas in the case of a formal language) each of which is an axiom or follows from the… … Wikipedia
FALLACY — arguments which seem correct but upon examination prove false. They are arguments which are PSYCHOLOGICALLY persuasive but logically wrong through mistakes in relating, inferring, or concluding, while reasoning. TRADITIONAL logic identified… … Concise dictionary of Religion
fallacy — Any error of reasoning. Reasoning may fail in many ways, and a great variety of fallacies have been distinguished and named. The main division is into formal fallacies in which something purports to be deductively valid reasoning but is not, and… … Philosophy dictionary
Reification (fallacy) — Contents 1 Etymology 2 Theory 3 Difference between reification and hypostatisation … Wikipedia
fallacy — /fal euh see/, n., pl. fallacies. 1. a deceptive, misleading, or false notion, belief, etc.: That the world is flat was at one time a popular fallacy. 2. a misleading or unsound argument. 3. deceptive, misleading, or false nature; erroneousness.… … Universalium
Informal fallacy — An informal fallacy is an argument whose stated premises fail to support their proposed conclusion. [Kelley, D. (1994) The Art of Reasoning . W W Norton amp; Company, Inc. ISBN 0 393 96466 3] The deviation in an informal fallacy often stems from… … Wikipedia
Necessary and sufficient condition — This article is about the formal terminology in logic. For causal meanings of the terms, see Causality. In logic, the words necessity and sufficiency refer to the implicational relationships between statements. The assertion that one statement is … Wikipedia
