Informal fallacy

An informal fallacy is an argument whose stated premises fail to support their proposed conclusion.^[1] 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.

Deductive and inductive informal fallacies

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 generalization, can be roughly stated as:

p) S is a P

p) S is also a Q

c) therefore, all Ps are also Qs

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 Ps and Qs is insufficient to represent the respective populations. 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

References

1. ^ Kelley, D. (1994) The Art of Reasoning. W W Norton & Company, Inc. ISBN 0-393-96466-3

Further reading

• 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, (2009). Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments (6E ed.). Wadsworth. ISBN 9780495095064. http://www.duxbury.com/cengage/instructor.do?product_isbn=9780495095064&disciplinenumber=5. 

External links

• Logical fallacies A list of logical fallacies, explained.
• An Informal Fallacy Primer
• The Fallacy Files: Informal Fallacy

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