Informal Fallacies

Informal fallacies are a broad category of mistakes within the content or reasoning of an argument.  Carelessness, ambiguity and irrelevance are root causes of informal fallacies. Formal fallacies are related to structure and form of an argument.


Accent Ambiguity of argument that results from improper tone of voice and emphasis on given proposition
Ambiguity Various informal fallacies that make communication unclear or ambiguous
Ab Annis Appeal to age as a basis of truth
Ad Baculum Appeal to force or fear as a determination of truth
Ad Futuris Appeal to future possibilities as a determinitive of truth
Ad Hominem Appeal to the person (abusive or circumstantial) as determinitive of truth
Ad Ignoratntiam Appeal to one’s lack of knowleddge or proof concerning an issue as determinitive of truth
Ad Misericordiam Appeal to pity or misery of an individual as determinitive of truth
Ad Populum Appeal to what is popular or in vogue as determinitive of truth
Amphibole Appeal to ambiguous propositions that cloud the meaning of a truth statement due to awkward wording
Analogy An attempt to use similarity that is irrelevant to the argument
Argument of the Beard Appealing to imperceptible differences among extremes to indicate there are no real differences among them
Category Mistake Confusing things in one category with things from another category: “What does the color red taste like?”
Composition Assuming that what is true of the parts is equally true of the whole
Dicto Simpliciter Attempting to apply a general rule to a specific case when differences exist that militate against its application
Division Assuming that what is true of a whole is also true of its parts
Equivocation Change in meaning of a word in the midst of an argument though the overall context remains the same; “Some horses have short tails.  My horse has a short tail. Therefore, my horse is some horse.”
False Cuase Assigning what is not the cause of a given effect as its real cause– as in crediting one event as the cause of another event simply because the first occurs prior to to the second.
False Dilemma Occurring when one is given only two alternatives to choose from when there are at least one or more additional alternatives.  “Either we allow abortion or we force the children to be raised by parents who do not want them”.
Hasty Generalization Reaching a conclusion after analyzing only unusual cases instead of reasoning from analysis of typical cases.
Petitio Principii
Non Sequitur Occurring when the conclusion does not follow from the premises.
Relevance Incorporating irrelevant material into an argument.
Slippery Slope Occurring when an individual claims that accepting a conclusion of an argument will lead to a series of undesirable consequences and justifications.
Straw Man Occurring when one interprets an opposing or alternative viewpoint in its weakest form or inaccurately and then rfeutes it as if the strength of the position are being addressed
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