Logical Fallacies — Definition, Types, & Examples

What is a logical fallacy?

A logical fallacy is an argument that contains an error in reasoning. All logical fallacies are non sequiturs, meaning the provided evidence (premise) does not logically support the conclusion.

Although logical fallacies are used within many types of arguments, the ability to recognize them can help people avoid understanding or agreeing to something based on erroneous logic and fallacious reasoning.

There are two main types of logical fallacies: formal fallacies, which have flaws in their structure, and informal fallacies, which have flaws in their content.

Types and examples of fallacies

The most common logical fallacies include the following:

• Ad Hominem Argument

• Appeal to Authority

• Appeal to Fear Fallacy

• Appeal to Hypocrisy

• Appeal to Ignorance

• Appeal to Pity

• Appeal to Reason Fallacy

• Bandwagon Fallacy

• Causal Fallacy

• Circular Reasoning Fallacy

• Either-or Fallacy

• Equivocation

• False Dilemma

• Guilt by Association Fallacy

• Hasty Generalization

• Moral Equivalence Fallacy

• Red Herring Fallacy

• Slippery Slope Fallacy

• Strawman Argument

• Testimonial Fallacy

• Weak Analogy

• Fallacy of Sunk Cost

Ad hominem

An ad hominem fallacy (argumentum ad hominem in Latin) occurs when someone attacks the source of an argument rather than the argument itself.

Just because Steve broke one rule does not mean he breaks them all.

Appeal to authority

The appeal to authority suggests that an argument is accurate despite no evidence because an expert in the subject area provided it.

A dentist’s background does not necessarily make them an authority on cryptocurrency.

Appeal to fear fallacy

The appeal to fear occurs when the arguer attempts to garner support for an idea by increasing the terror of its alternative.

To convince a homeowner to purchase the updated security system, the company utilizes fear in suggesting what would happen to the home.

Appeal to hypocrisy

The appeal to hypocrisy, or tu quoque, happens when an opponent is attacked for not acting in accordance with their own argument, evoking a “do as I say, not as I do” mentality.

The speaker highlights the hypocrisy created by the dad not eating vegetables.

Appeal to ignorance

An appeal to ignorance is an argument that something must be true because there is no evidence to prove it is false.

The argument is that since there is no proof that aliens don’t exist, they must exist.

Appeal to pity

An appeal to pity makes an argument that manipulates someone’s feelings of sympathy to gain their support.

The student tries to instill a sense of pity by referencing their lonely brother.

Bandwagon fallacy

Also known as the appeal to common belief or appeal to the masses, the bandwagon fallacy suggests something is true because most people believe it to be.

Just because everyone has the new iPhone does not mean it is a good product.

Causal fallacy

Causal fallacies occur when an argument attributes an effect to an incorrect cause. This fallacy is also known as “post hoc ego propter hoc,” stating that if event X occurred after event Y, then Y caused X.

The individual suggests that it rains because her windows are open. The correlation she has noticed does not equal causation.

Circular reasoning fallacy

A circular argument happens when the conclusion of an argument is considered true and used as evidence to support the conclusion.

The speaker uses the point of laws to prove why they must be followed.

False dilemma fallacy

Also known as the either-or fallacy and false dichotomy, the false dilemma fallacy presents an invalid argument by suggesting there are only two options even though there could be many more sides.

The politician argues that not voting for him would result in higher taxes, providing the people with only two options – one positive and one negative.

Fallacy of equivocation

The equivocation fallacy, also known as the weak analogy fallacy, occurs when a word or phrase has multiple meanings but only one is applied to prove an argument.

The argument applies two different meanings of "light" to two objects that do not share both characteristics.

Guilt by association fallacy

When someone connects an opponent to a person or group with a negative reputation, they use the guilt by association fallacy.

The suggestion that a student will not be valedictorian because their sibling was not a good student provides an erroneous connection.

Hasty generalization

A hasty generalization occurs when the provided evidence does not logically support the identified conclusion.

Indicating that an entire city must be rude due to the actions of one individual is an ill-informed conclusion.

Moral equivalence fallacy

The moral equivalence draws a comparison between two different or unrelated ideas to suggest that one is as bad (or as good) as the other.

Despite their similarities, apples and oranges do not taste the same.

Red herring fallacy

Individuals use the red herring fallacy to redirect an argument to another issue. They do this to avoid or abandon the original argument and distract people away from something important.

The individual avoids answering the question by bringing up the unrelated topic of a math test.

Slippery slope fallacy

The slippery slope fallacy occurs when an individual suggests that a certain course of action could eventually lead to larger and larger negative effects.

This logic suggests that allowing students to retake a quiz could rise to the students being able to retake an entire grade level.

Strawman argument

When someone misrepresents or exaggerates their opponent’s argument, they use the strawman fallacy. The misrepresentation is meant to help their argument look more reasonable.

Suggesting that the home will be defenseless without the updated security exaggerates the homeowner's position.

Testimonial fallacy

A testimonial fallacy happens when a popular or respected figure endorses a certain argument, yet they lack any expertise in the subject matter being argued.

Someone simply having a connection to a subject does not make them an expert.

Fallacy of sunk costs

Fallacy of sunk costs occurs when someone has invested so much time and effort into an undertaking even if the costs no longer outweigh the benefits.

The viewer has put so much time into the show that he continues to watch it, even though he no longer finds it interesting.