An informal fallacy occurs in 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 fallacies of deductive reasoning fail to guarantee a true conclusion follows given the truth of the premises. This will 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). In other words, informal fallacies are not necessarily incorrect. However they often need the backing of empirical proof to become convincing.
For instance, the fallacy of hasty generalization, can be roughly stated as an invalid syllogism. Hasty generalisation often follows a pattern such as:
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.