An informal fallacy is an argument whose stated premises may fail to adequately support its proposed conclusion. The problem with an informal fallacy often stems from reasoning that renders the conclusion unpersuasive. In contrast to a formal fallacy of deduction, the error is not a flaw in logic.
Formal deductive fallacies and informal fallacies
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:
Hasty generalization usually shows this pattern:
X is true for A.
X is true for B.
X is true for C.
X is true for D.
Therefore, X is true for E, F, G, etc.
While never a valid logical deduction, if such an inference can be made on statistical grounds, it may nonetheless be convincing.
This is to say that informal fallacies are not necessarily incorrect, nor are they logical fallacies. However they often need the backing of empirical proof to become convincing.
- Kelly, D. (1994) The Art of Reasoning. W W Norton & Company, Inc. ISBN 0-393-96466-3
- Damer, T. Edward (2009), Attacking Faulty Reasoning: A Practical Guide to Fallacy-free Arguments (6th ed.), Wadsworth, ISBN 978-0-495-09506-4