Common Logical Fallacies in Critical Thinking and Argumentation

Fallacy

An error of reasoning that may sound reasonable or true but is deceptive and dishonest.

Ad Hominem

A personal attack not relevant to the argument, diverting attention from the facts by attacking the motives or character of the other person.

Ad Hominem (Abusive)

"The public should not take seriously Dr. Mason's plan for upgrading county health services. He is a recovering alcoholic whose second wife recently divorced him."

Ad Hominem (Circumstantial)

"Of course he thinks fraternities are great. He's a Phi Delta."

Tu Quoque

Asserts that an opponent's argument has no value because the opponent does (or did) not follow his or her own advice.

Tu Quoque

"How can that judge favor stronger penalties for convicted drug dealers? During his confirmation hearings, he admitted he had smoked marijuana as a student."

Straw Man Argument

Distorts somebody's position in order to make it easier to attack.

Straw Man

A politician attacking his opponent for advocating a decrease in the rate of growth in Social Security spending: "He's for taking away your Social Security!"

Appeal to Doubtful Authority

Attempts to bolster an argument with references to experts or famous people, which is only valid if the person cited is an expert in the area being discussed.

Appeal to Doubtful Authority

"According to Bill Nye, if the rainforest continues to be cut at the present rate, it will be gone in a mere decade."

Appeal to Fear

Attempts to convince by implicitly threatening the audience, based on emotion rather than reason.

Appeal to Fear

An ad for a business college: "Will there be a job waiting when you leave college?"

Appeal to Pity

Attempts to win sympathy in order to convince of the conclusion.

Appeal to Pity

"But Mr. Hodges, if I don't get an A in your course, I won't get into a good college."

Ad Populum

Argues that everyone is doing it; so should you.

Ad Populum

"Don't be left out! Buy your Ford Explorer today!"

Begging the Question

A circular argument that assumes an answer to the very point in dispute, offering no actual support.

Begging the Question

"Students like rock music because it is the most enjoyable music around."

More Question-Begging

Question: Why should I believe the Bible? Answer: Because the Bible says so.

Poisoning The Well

A person poisons the well when he or she makes an assertion that precludes or discourages an open discussion of the issue.

False Dilemma

Often referred to as either/or reasoning; suggests that only two alternatives exist even though there may be others.

False Cause

Also called post hoc reasoning; assumes a cause/effect relationship between two events because one precedes the other.

Slippery Slope

One thing leads to another; an action should be avoided because it will inevitably lead to a series of extremely undesirable consequences.

Hasty Generalization

A conclusion is reached on too little evidence; based on a sample that is too small or otherwise unrepresentative.

Non Sequitur

When a statement does not logically follow from a previous statement.

False Analogy

A false analogy compares two things in which key features are different.

Equivocation

The meaning of a key term changes at some point in the argument; stems from the ambiguous nature of language.

False Dilemma

Either you are in favor of recalling the mayor, or you are a supporter of her political platform.

False Cause

Governor Smith took office in 1995. In 1996, the state suffered a severe recession. Therefore, Governor Smith should not be re-elected.

Slippery Slope

An action should be avoided because it will inevitably lead to a series of extremely undesirable consequences.

Hasty Generalization

Our son Marc really benefited socially from going to nursery school; I think every child should go.

Non Sequitur

Most gun crimes are committed with unregistered guns; therefore, requiring gun-registration will reduce crime.

False Analogy

Improving one's appearance through cosmetic surgery is no different than using makeup or hair-coloring.

Equivocation

Some dogs have fuzzy ears. My dog has fuzzy ears. My dog is some dog.

Conclusion

Don't be fooled by misleading and deceptive arguments; learn how to distinguish fallacious arguments.