Logical Fallacies

A logical fallacy is an error in logic—something that makes your argument suspect, incomplete, and/or untrue. Fallacies may be either careless mistakes or intentional deceptions. You should always ensure that you base your reasons and your conclusions on carefully thought out elements.

Argument to the man: Circumventing an issue by attacking a person’s character. Used to divert an audience’s attention.

Argument to the people: Seeking assent by stirring up powerful emotions (such as fear or prejudice) rather than building a logical case. Used to divert an audience’s attention.

Begging the question: Circular reasoning—that is, drawing conclusions from assumptions that have not been proven.

Complex question: A question such as “Where did you go after you stole the car?”; that is, a question that actually contains two questions that must be addressed separately—first “Did you steal the car?” and then “Where did you go?”

Either/or fallacy: Contrasting your own choice only with one that is wholly undesirable, while overlooking other options.

Equivocation: Using a word with two or more definitions, usually in order to confuse or deceive.

Faulty causation: An illogical assumption about what caused an effect to take place. One type is the post hoc fallacy, from post hoc, ergo propter hoc, which means, “After this, therefore because of this.” In other words, you’ve assumed that because one thing came before another thing, the first caused the second.

Faulty generalization: Making a general statement or claim based on insufficient evidence—in other words, jumping to conclusions. Stereotypes, for example, arise from faulty generalizations.

False analogy: Assuming that since two things are alike in one respect, they must be alike in others. Often, an analogy is false because important pieces of information are missing or overlooked.

Half-truth: Building your argument on verifiable facts but deliberately failing to give your audience the full story. In other words, if providing more information would shed a different light on what you’re saying, you’re deceiving your audience. Omitting key facts and details often can be just as harmful to your credibility as giving facts that are blatantly untrue.

Non sequitur: Literally, “does not follow.” A conclusion or statement that does not arise logically from the premises of a given argument.

Red herring: Avoiding the “real” argument by introducing something irrelevant or tangentially related, thereby changing or shifting the topic of discussion.

Straw man fallacy: Attempting to strengthen your own view by distorting the opposing view or making it seem overly simplistic. The opposing view thus becomes a “straw man” that you can knock down easily. This technique usually hurts your credibility.