Informal Fallacy

Taxonomy: Logical Fallacy > Informal Fallacy


An informal fallacy is one that is not formal, that is, it is a type of fallacy in which the content of the argument is relevant to its fallaciousness, or which is fallacious for dialectical, epistemological, or linguistic reasons―see the Exposure, below. Typically, informal fallacies occur in non-deductive reasoning, which relies on content as well as form for cogency. Also, because content is important in informal fallacies, there are cogent arguments with the form of the fallacy. For this reason, when forms are given in the entries for individual informal fallacies, this is for identification purposes only―that is, one cannot tell from the form alone that an instance is fallacious, since content is also relevant. Rather, the forms will help to differentiate between distinct types of informal fallacy.

As a logical fallacy, Informal Fallacy is the most general fallacy committed by arguments that are fallacious for informal reasons. However, a given fallacious argument would be classified as an Informal Fallacy only if it could not be given a more specific classification. For this reason, there is no Example of Informal Fallacy given; instead, see the Examples under the Subfallacies, below.


As mentioned above, fallacies can be informal for the following reasons, among others:


Accident, Ambiguity, Appeal to Ignorance, Begging the Question, Black-or-White Fallacy, Composition, Division, Non Causa Pro Causa, One-Sidedness, Red Herring Fallacy, Special Pleading, Vagueness, Weak Analogy


S. Morris Engel, With Good Reason: An Introduction to Informal Fallacies (Fifth Edition) (St. Martin's, 1994). A textbook.