Kreeft Logical Fallacies

Post hoc

(Fallacies of induction) Full name is "post hoc, ergo propter hoc." In English, "After this, therefore because of this." It is the fallacy of causal induction (that form of induction which consists in reasoning to a cause), and it consists in inferring that one thing is the cause of another simply because the first thing is observed to occur before the second thing.

Argument from silence

(Fallacies of induction) The fallacy that when someone does not speak on something (they are silent on it) they are indicating something or another about the topic they have not mentioned.

Hasty Generalization

(Fallacies of induction) The inference from some specific examples to a general principle. Mere examples never conclusively prove a general principle of course; they only render it more probable.

Hypothesis Contrary to Fact

(Fallacies of induction) This could be called the "if only" fallacy, for it consists in arguing that if only x were true, which it isn't, then y would be true. It is a fallacy of causal induction because it claims to know that non-x is the cause of y.

Selective evidence

(Fallacies of induction) This extremely common fallacy consists simply in referring only to the evidence that tends to support your hypothesis and ignoring the evidence that tends to refute it.

Slanting the Question

(Fallacies of induction) This is a fallacy that occurs especially in polls. A questioner can often gain a favorable response if only they word their question in a way that is likely to be responded to favorably.

False analogy

(Fallacies of induction) This is another form of induction. These are rightly used to illustrate general principles through a comparison of similar circumstances, but they do not prove anything; this fallacy assumes that the use of these proves a conclusion.

Special case

(Fallacy of Oversimplification) Exactly the reverse of dicto simpliciter. Dicto simpliciter argues that something is true simply, therefore it is true in some special case. This fallacy argues that something is true in some special case, therefore it is true simply. Both fallacies ignore the specialness of the special case.

Quoting out of context

(Fallacy of Oversimplification) Literally quoting out of context. It comes in two main forms: the context that is ignored can be either literary or real. In the literary form, it is simply the text before and after the quoted part that is the context ignored. In the other form, it is the real, lived situation surrounding the spoken words.

Dicto simpliciter

(Fallacy of Oversimplification) Most obvious and direct of the fallacies of oversimplification; means saying something too simply, absolutely, or unqualifiedly; that is, applying a general principle to a special case without the needed qualification.

Composition

(Fallacy of Oversimplification) This fallacy consists in arguing from the part to the whole, ignoring the fact that what is true of the part is not necessarily true of the whole.

The black and white fallacy

(Fallacy of Oversimplification) This is similar to dicto simpliciter but the fallacy here consists in not allowing for gradations or means between extremes; dicto simpliciter consisted in not allowing for exceptions to a simple rule. The fallacy here consists in arguing "it is not this one extreme, therefore it must be the opposite extreme."

Division

(Fallacy of Oversimplification) This is the reverse of composition; it consists in arguing from whole to part, ignoring the fact that what is true of the whole is not always true of the part.

Stereotyping

(Fallacy of Oversimplification) Type of generalization. These are not the same as archetypes in that they are artificial, socially-fabricated, and unchangeable.

Begging the question

(Fallacy of argumentation) Also, Petitio Principii. Means, assuming what you set out to prove, smuggling the conclusion back into the premises, usually under different words.

Ignoratio Elenchi

(Fallacy of argumentation) Could be called fallacy of "missing the point." Also, Irrelevant conclusion, or "ignorance of the chain" connecting premises and conclusion, or "false refutation." It consists in giving reasons that prove a different conclusion than the one the argument purports to prove.

Contradictory premises

(Fallacy of argumentation) Literally when the premises of an argument are contradictory.

Non sequitur

(Fallacy of argumentation) Means: "It does not follow." The conclusion simply does not logically follow from the premises or reasons or evidence given. This is a material fallacy, not a formal one.

Arguing in a circle

(Fallacy of argumentation) This fallacy consists in using a conclusion to justify a premise after having used that premise to justify that conclusion. Thus it is really another version of begging the question, assuming what you are supposed to prove, but this time not just assuming it but also using it as a premise to prove your other proposition.

Complex question

(Fallacy of argumentation) This fallacy consists of asking a question which cannot be answered without "begging" another question. Example: "Have you stopped beating your wife?"

False assumption

(Fallacy of argumentation) This fallacy is similar to begging the question but the false assumption is more covert. It is the basis for many jokes. Example: "Life is not a problem, so why are you asking for a solution?" (Alan Watts)

Ad baculum

(Fallacy of diversion) Also, the appeal to force. The fear of force instead of reason.

Ad ignorantiam

(Fallacy of diversion) Also, the appeal to ignorance. Consists in arguing that an idea must be true because we do not know that it is not. It is a fallacy because ignorance can never be a premise or reason.

Ad Verecundiam

(Fallacy of diversion) Also, the appeal to illegitimate authority. Means "the appeal to reverence." The fallacy is the illegitimate appeal to authority, or the appeal to illegitimate authority. The authority can either be 1) irrelevant 2) unreliable 3) unnecessary 4) dogmatic or 5) uncritical

Ad misericordiam

(Fallacy of diversion) Also, the appeal to pity. It is the perversion of something that is perfectly legitimate in itself, just as is the appeal to authority. Pity is usually a good thing, but it cannot be a substitute for argument.

Ad ignominiam

(Fallacy of diversion) Also, the appeal to shame. Shame itself is not a fallacy; but deciding what to do or say by appealing only to shame is a logical fallacy because it is a diversion from objective truth, facts, and evidence.

Ad populum

(Fallacy of diversion) Also, the appeal to the masses. Includes flattery, identification, "everybody does it," "the polls say," the appeal to prejudice, "snob appeal," and "the big lie."

Ad hominem

(Fallacy of diversion) Also, the appeal to the person. Includes "poisoning the well," Tu quoque, and the genetic fallacy. Means an "argument addressed to the person" instead of to the issue. In other words a personal attack, attacking the person instead of attacking the issue.

Straw Man

(Fallacy of language) Consists in refuting an unfairly weak stupid, or ridiculous version of your opponent's idea (either his conclusion or his argument) instead of the more reasonable idea he actually holds.

Slogans

(Fallacy of language) Essentially a catch phrase used in substitute for an actual argument. Used to produce a thoughtless knee-jerk reaction of agreement or disagreement simply on the basis of the familiarity of the words rather than on the basis of reason.

Accent

(Fallacy of language) Here the ambiguity comes from voice inflection ironic or sarcastic tone, or even facial expression or innuendo.

Hyperbole

(Fallacy of language) Means "exaggeration." Routinely done by "media hype." Example: the word crisis constantly used in the news to attract attention or inflate a point.

Amphiboly

(Fallacy of language) Not an ambiguous word or phrase but ambiguous syntax (word order or grammatical structure).

Equivocation

(Fallacy of language) Simplest and most common of all material fallacies. It means simply that the same term is used in two or more different senses in the course of an argument.

Slanting

(Fallacy of language) Sometimes called the fallacy of the "question-begging epithet" because it is really a form of "begging the question" in a single word. This type of language begs the question by telling you whether to like or dislike the thing the word describes. Instead of proving that the thing it describes is good or bad, it assumes its value or disvalue in the very description of it. Example: propaganda.

Shifting the burden of proof

(Procedural fallacy) Quibbling over who has or has not proven the burden of proof in an argument. The easiest way to avoid this is to settle the burden before the argument commences.