Formal Deductive Fallacies and Informal Fallacies
Formal fallacies of deductive reasoning fail to follow the rules of logic that guarantee a true conclusion follows given the truth of the premises. This is said to render the argument invalid.
Inductive fallacies are not formal in this sense. Their merit is judged in terms of rational persuasiveness, inductive strength or methodology (for example, statistical inference). For instance, the fallacy of hasty generalization, can be roughly stated as an invalid syllogism:
- A is an X
- A is also a Y
- Therefore, all Xs are also Ys
While never a valid deduction, if such an inference can made on statistical grounds, it may nonetheless be convincing.
Read more about this topic: Informal Fallacy
Famous quotes containing the words formal and/or informal:
“It is in the nature of allegory, as opposed to symbolism, to beg the question of absolute reality. The allegorist avails himself of a formal correspondence between “ideas” and “things,” both of which he assumes as given; he need not inquire whether either sphere is “real” or whether, in the final analysis, reality consists in their interaction.”
—Charles, Jr. Feidelson, U.S. educator, critic. Symbolism and American Literature, ch. 1, University of Chicago Press (1953)
“We are now a nation of people in daily contact with strangers. Thanks to mass transportation, school administrators and teachers often live many miles from the neighborhood schoolhouse. They are no longer in daily informal contact with parents, ministers, and other institution leaders . . . [and are] no longer a natural extension of parental authority.”
—James P. Comer (20th century)