Informal fallacy

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 & Company, Inc. ISBN 0-393-96466-3] The deviation in an informal fallacy often stems from a flaw in the path of reasoning that links the premises to the conclusion. In contrast to a formal fallacy, the error has to do with issues of ratiocination manifest in language used to state the propositions; the range of elements that can be symbolized by language is broader than that which the symbolism of formal logic can represent. Informal fallacies of deductive reasoning contain a fundamental disconnect between the premises and the conclusion that renders the argument invalid. This disconnect often stems from the presence of a hidden co-premise that, if presented, would validate the argument.

Inductive informal fallacies are slightly different than their deductive counterparts, as their merit rests in the inductive strength of the premise-conclusion link rather than in the presence of hidden premises. For instance, the fallacy of hasty generalisation, can be roughly stated as:

:p) "S" is a "P":p) "S" is also a "Q":c) therefore, all "P"s are also "Q"s

If the populations of "P" and "Q" are both too large to sample completely, then the statement is inductive. In such a case, a hasty generalization occurs when the number of "P"s and "Q"s is insufficient to represent the respective populations. [In other words, when you fail to mind your "P"s and "Q"s!] It is important to distinguish between a principle of reasoning (deductive or inductive) and the premise of an argument.

See also

* Argumentation theory
* Argument map
* Critical thinking
* Inference objection
* Inquiry
* Lemma
* Sophism


Further reading

* cite book
author = Damer, T. E.; Rudinow, J.; Barry, V. E.; Munson, R.; Black, A.; Salmon, M. H.; Cederblom, J.; Paulsen, D.; Epstein, R. L.; Kernberger, C.; Others,
title=Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments
year = 2009
edition = 6E
url =
isbn = 9780495095064
publisher = Wadsworth

External links

* " [ Logical fallacies] " A list of logical fallacies, explained.
* " [ An Informal Fallacy Primer] "

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