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:
“On every formal visit a child ought to be of the party, by way of provision for discourse.”
—Jane Austen (1775–1817)
“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)