Critical Reasoning Fallacies

(false comparison) All Natural Fallacy

Assuming that members of the same family share all the same traits, so that anything “natural”must be good for you (Heinrichs only)

(false comparison) Appeal to Popularity

Assuming that something must be true or desirable simply because many people favor it. (Both text latin name ad populum)

(false comparison) Reductio ad absurdum

In Heinrich’s usage, falsely comparing a choice with a ridiculous one. Heinrichs only; in standard logic, the term names a valid form of refutation.

(false comparison) Fallacy of antecedent

Assuming the future must repeat the past: it never happened, so it never will, or it happened once, so it will again. Heinrichs only.

(false comparison) False analogy

Assuming that because I can do one thing well, I can do an unrelated thing just as well. Heinrichs only.

(false comparison) Pathetic fallacy (anthropomorphism)

Treating nonhuman things as human because they seem to act human. Heinrichs only, as a type of false analogy.

(false comparison) Unit fallacy

Mistaking one kind of unit for another, often confusing a part of a part with a part of the whole. Heinrichs only.

(weak or missing evidence) Misinterpreting the evidence

Drawing a broad conclusion from unrepresentative examples. Heinrichs only.

(weak or missing evidence) Hasty generalization

Reaching a sweeping conclusion from too few examples. Heinrichs only.

(weak or missing evidence) Fallacy of ignorance

Assuming that what we cannot prove must not exist, or that what we cannot disprove must exist. Heinrich’s only.

(weak or missing evidence) Appeal to questionable authority

Supporting a conclusion by citing an authority who lacks special expertise on the issue at hand. Browne and Keeley only.

(limited choices) False dilemma

Assuming there are only two alternatives when there are actually more. Both texts; Browne and Keeley call it “either-or.”

(limited choices) Many questions

Merging two or more issues into one, so that answering one question concedes another. Heinrichs only; often called the loaded or complex question.

(limited choices) Searching for perfect solution

Assuming a solution should be rejected because part of the problem would remain after it is tried. Browne and Keeley only; it offers a false choice between a perfect solution and none at all.

(cause, explanation and prediction) Narrative

Assuming that because we can tell a story that seems to explain a set of facts, we understand how those facts are actually connected. Browne and Keeley only.

(cause, explanation and prediction) Explaining by naming

Falsely assuming that giving a label to a behavior or event explains what caused it. Browne and Keeley only.

(cause, explanation and prediction) Complex cause

Giving one cause all the blame (or credit) for an outcome that has many causes. Heinrichs only; he places it under the false choice, since it narrows the number of causes.

(cause, explanation and prediction) Chanticleer fallacy (post hoc ergo propter hoc).

Assuming that because one thing followed another, the first caused the second. Heinrichs only; “Chanticleer fallacy” is his own name for it.

(cause, explanation and prediction) Slippery slope.

Assuming that one step will set off an uncontrollable chain of bad outcomes, when there are ways to stop that chain. Both texts; Browne and Keeley list it among faulty assumptions, and Heinrichs among wrong endings.

(cause, explanation and prediction) Planning fallacy.

Underestimating how long a task will take, despite plenty of past experience of underestimating similar tasks. Browne and Keeley only.

(divert attention) Red herring.

Introducing an irrelevant topic as though it were relevant, so that the original issue is abandoned. Both texts; Heinrichs also calls it the “Chewbacca defense.”

(divert attention) Straw man.

Distorting an opponent’s position into a weaker version that is easy to attack, and then attacking that version instead. Both texts; Browne and Keeley call it the “straw person,” and Heinrichs treats it as a version of the red herring.

(divert attention) Ad hominem.

Attacking the person making an argument instead of addressing that person’s reasons. Browne and Keeley only.

(divert attention) Appeal to emotion.

Using emotionally charged language, such as appeals to fear, pity or patriotism, to distract from relevant reasons and evidence. Browne and Keeley only; Heinrichs treats emotional appeals as a legitimate part of rhetoric.

(divert attention) Glittering generality.

Using vague, positive virtue words that dispose us to approve of something without examining the reasons for it. Browne and Keeley only.

(asume what they should prove) Begging the question.

Offering a reason that simply restates the conclusion in different words, so that the conclusion is assumed rather than proven. Both texts; Heinrichs calls it the “tautology” and prefers that term.