Logical fallacy

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In philosophy, a logical fallacy or a formal fallacy is a pattern of reasoning which is always or at least most commonly 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 fallacy, which has a valid logical form, but is false due to one or more of its premises being false.

The term fallacy is often used more generally to mean an argument which is problematic for any reason, whether it be a formal or an informal fallacy.

1 Common examples
2 See also
3 References
4 External links

The presence of a formal fallacy in a deductive argument does not imply anything about the argument's premises or its conclusion. Both may actually be true, or even more probable as a result of the argument (e.g. appeal to authority), but the deductive argument is still invalid because the conclusion does not follow from the premises in the manner described. By extension, an argument can contain a formal fallacy even if the argument is not a deductive one; for instance an inductive argument that incorrectly applies principles of probability or causality can be said to commit a formal fallacy.

Recognizing fallacies in everyday arguments may be difficult since arguments are often embedded in rhetorical patterns that obscure the logical connections between statements. Informal fallacies may also exploit the emotions or intellectual or psychological weaknesses of the audience. Having the capability to recognize fallacies in arguments is one way to reduce the likelihood of such occurrences.

A different approach to understanding and classifying fallacies is provided by argumentation theory; see for instance the van Eemeren, Grootendorst reference below. In this approach, an argument is regarded as an interactive protocol between individuals which attempts to resolve a disagreement. The protocol is regulated by certain rules of interaction and violations of these rules are fallacies. Many of the fallacies in the list below are best understood as being fallacies in this sense.

[edit] Common examples

Formal fallacies
- Argument from fallacy "ad logicam"
- Affirming the consequent or Denying the antecedent
Faulty generalization Inductive fallacies like
Questionable cause Informal causal fallacies
- Begging the question, circular logic "petitio principii"
- Correlation implies causation "Cum hoc ergo propter hoc"
- Post hoc ergo propter hoc
- Appeal to consequences "ad consequentiam"
- Appeal to force "Ad baculum"
- Appeal to probability & Slippery slope
Informal Relevance fallacies
- Irrelevant conclusion "Ignoratio elenchi" like Red Herring
- Straw man
- Association fallacy
- Ad hoc
- Argument from ignorance, incredulity, belief, conviction... "ad ignorantiam"
- Appeal to emotion like Appeal to fear, Appeal to flattery, Appeal to pity, Appeal to spite...
- Wishful thinking
- Appeal to authority or Appeal to ridicule "Ad hominem"
- Appeal to the majority "ad populum"
- Appeal to tradition "ad antiquitatem"
Informal Verbal fallacies
- Equivocation & Loki's Wager
- Undistributed middle & No true Scotsman

For a list of types of formal and informal fallacy, as well as examples of fallacious arguments, see Fallacy. For a concise list of "appeal to" fallacies, see Appeal (disambiguation).

[edit] See also

[edit] References

Aristotle, On Sophistical Refutations, De Sophistici Elenchi.
William of Ockham, Summa of Logic (ca. 1323) Part III.4.
John Buridan, Summulae de dialectica Book VII.
Francis Bacon, the doctrine of the idols in Novum Organum Scientiarum, Aphorisms concerning The Interpretation of Nature and the Kingdom of Man, XXIIIff.
The Art of Controversy | Die Kunst, Recht zu behalten - The Art Of Controversy (bilingual), by Arthur Schopenhauer
John Stuart Mill, A System of Logic - Raciocinative and Inductive. Book 5, Chapter 7, Fallacies of Confusion.
C. L. Hamblin, Fallacies. Methuen London, 1970.
Fearnside, W. Ward and William B. Holther, Fallacy: The Counterfeit of Argument, 1959.
Vincent F. Hendricks, Thought 2 Talk: A Crash Course in Reflection and Expression, New York: Automatic Press / VIP, 2005, ISBN 87-991013-7-8
D. H. Fischer, Historians' Fallacies: Toward a Logic of Historical Thought, Harper Torchbooks, 1970.
Douglas N. Walton, Informal logic: A handbook for critical argumentation. Cambridge University Press, 1989.
F. H. van Eemeren and R. Grootendorst, Argumentation, Communication and Fallacies: A Pragma-Dialectical Perspective, Lawrence Erlbaum and Associates, 1992.
Warburton Nigel, Thinking from A to Z, Routledge 1998.
T. Edward Damer. Attacking Faulty Reasoning, 5th Edition, Wadsworth, 2005. ISBN 0-534-60516-8
Sagan, Carl, "The Demon-Haunted World: Science As a Candle in the Dark". Ballantine Books, March 1997 ISBN 0-345-40946-9, 480 pgs. 1996 hardback edition: Random House, ISBN 0-394-53512-X, xv+457 pages plus addenda insert (some printings).