Formal Fallacy

Exposition:

A Formal Fallacy is a type of argument the logical form of which is non-validating, and which is either:

• Deceptive and likely to be committed, usually by having a logical form that is similar to a validating form of argument.
• Part of a system of rules such that any argument of a type which the rules can be applied to, and which commits no fallacy, thereby breaks no rules. See Syllogistic Fallacy.

The distinction between a Formal and an Informal Fallacy is that a formal fallacy is based solely on logical form, and an informal fallacy takes into account the non-logical content of the argument. This roughly parallels the distinction between deductive and non-deductive modes of reasoning. Typically, formal fallacies occur within deductive contexts, whereas informal fallacies are committed by arguments that could be at best inductively strong. However, there are exceptions to this pattern, for instance Begging the Question.

Source:

Robert Audi (General Editor), The Cambridge Dictionary of Philosophy, 1995.

Subfallacies:

• Bad Reasons Fallacy
• Fallacy of Modal Logic
• Fallacy of Propositional Logic
• Fallacy of Quantificational Logic
• Masked Man Fallacy
• Probabilistic Fallacy
• Syllogistic Fallacy