In my various debates on the net and elsewhere, I find that often when I accuse an opponent of fallacious reasoning he is either entirely unfamiliar with the fallacy I mention, isn't thoroughly convinced the fallacy is a bad thing, or thinks he knows what the fallacy is but is mistaken. I don't know how many times I have been told that an ad hominem argument is not really ad hominem because the author of the gem didn't mean to hurt someone's feelings, or that the fact that some analogy I just used was not identical in every respect to the case at hand somehow made it a false analogy. To combat this kind of thing I have captured here for your enjoyment and edification a fine collection of classic fallacies known for their error throughout the ages. I plan to make extensive use of them in my other writings so that if I want to point out that someone is posing a false dilemma for example, I can avoid having to yet again explain what that is and why it is wrong. You are certainly welcome to do that same.
So enjoy the show, please stay behind the ropes, and for god's sake don't feed the fallacies!
Fallacies of DistractionFalse Dilemma: two choices are given when in fact there are three or more options
From Ignorance: because something is not known to be true, it is assumed to be false
Slippery Slope: a series of increasingly unacceptable consequences is drawn
Complex Question: two unrelated points are conjoined as a single proposition
Appeals to Motives in Place of SupportAppeal to Force: the reader is persuaded to agree by force
Appeal to Pity: the reader is persuaded to agree by sympathy
Consequences: the reader is warned of unacceptable consequences
Prejudicial Language: value or moral goodness is attached to believing the author
Popularity: a proposition is argued to be true because it is widely held to be true
Changing the SubjectAttacking the Person:(1) the person's character is attackedAppeal to Authority:
(2) the person's circumstances are noted
(3) the person does not practise what is preached
(1) the authority is not an expert in the fieldAnonymous Authority: the authority in question is not named
(2) experts in the field disagree
(3) the authority was joking, drunk, or in some other way not being serious
Style Over Substance: the manner in which an argument (or arguer) is presented is felt to affect the truth of the conclusion
Inductive FallaciesHasty Generalization: the sample is too small to support an inductive generalization about a population
Unrepresentative Sample: the sample is unrepresentative of the sample as a whole
False Analogy: the two objects or events being compared are relevantly dissimilar
Slothful Induction: the conclusion of a strong inductive argument is denied despite the evidence to the contrary
Fallacy of Exclusion: evidence which would change the outcome of an inductive argument is excluded from consideration
Fallacies Involving Statistical SyllogismsAccident: a generalization is applied when circumstances suggest that there should be an exception
Converse Accident : an exception is applied in circumstances where a generalization should apply
Causal FallaciesPost Hoc Ergo Propter Hoc: because one thing follows another, it is held to cause the other
Joint effect: one thing is held to cause another when in fact they are both the joint effects of an underlying cause
Insignificant: one thing is held to cause another, and it does, but it is insignificant compared to other causes of the effect
Wrong Direction: the direction between cause and effect is reversed
Complex Cause: the cause identified is only a part of the entire cause of the effect
Missing the PointBegging the Question: the truth of the conclusion is assumed by the premises
Irrelevant Conclusion: an argument in defense of one conclusion instead proves a different conclusion
Straw Man: the author attacks an argument different from (and weaker than) the opposition's best argument
Fallacies of AmbiguityAmphiboly: the structure of a sentence allows two different interpretations
Accent: the emphasis on a word or phrase suggests a meaning contrary to what the sentence actually says
Category ErrorsComposition: because the attributes of the parts of a whole have a certain property, it is argued that the whole has that property
Division: because the whole has a certain property, it is argued that the parts have that property
Non SequiturAffirming the Consequent: any argument of the form: If A then B, B, therefore A
Denying the Antecedent: any argument of the form: If A then B, Not A, thus Not B
Inconsistency: asserting that contrary or contradictory statements are both true
Stolen Concept: using a concept while attacking a concept on which it logically depends
Barker, Stephen F. The Elements of Logic. Fifth Edition. McGraw-Hill, 1989.
Cedarblom, Jerry, and Paulsen, David W. Critical Reasoning. Third Edition. Wadsworth, 1991.
Copi, Irving M., and Cohen, Carl. Introduction to Logic. Eighth Edition. Macmillan, 1990.
Rand, Ayn Introduction to Objectivist Epistemology. Second Edition. Penguin, 1990.
Special thanks to firstname.lastname@example.org for much of the research on which this stuff is based.
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