Logical Fallacies

Fallacies are defects that weaken arguments. By learning to look for them in your own and others’ writing, you can strengthen your ability to evaluate the arguments you make, read, and hear.  The examples below are a sample of the most common fallacies.

Common Fallacies: Emotional

The fallacies below appeal to inappropriately evoked emotions instead of using logic, facts, and evidence to support claims.

  • Ad Hominem (Argument to the Man): attacking a person’s character instead of the content of that person’s argument. Not simply name-calling, this argument suggests that the argument is flawed because of its source.

For example, David Horowitz as quoted in the Daily Pennsylvanian: “Anyone who says that about me [that he’s a racist bigot] is a Nazi.”

  • Argumentum Ad Ignorantiam (Argument From Ignorance): concluding that something is true since you can’t prove it is false.

For example “God must exist, since no one can demonstrate that she does not exist.”

  • Argumentum Ad Misericordiam (Appeal To Pity): appealing to a person’s unfortunate circumstance as a way of getting someone to accept a conclusion.

For example, “You need to pass me in this course, since I’ll lose my scholarship if you don’t.”

  • Argumentum Ad Populum (Argument To The People): going along with the crowd in support of a conclusion.

For example, “The majority of Americans think we should have military operations in Afghanistan; therefore, it’s the right thing to do.”

  • Argumentum Ad Verecundiam (Appeal to False Authority): appealing to a popular figure who is not an authority in that area.

For example, “Bruce Willis supports Save the Whales International, so it must be a good cause.”

Common Fallacies: Logical

The fallacies below are errors in reasoning that will undermine the logic of an argument.

  • Hasty Generalization: making assumptions about a whole group or range of cases based on a sample that is inadequate (usually because it is atypical or just too small). Stereotypes about people (“frat boys are drunkards,” “grad students are nerdy,” etc.) are a common example of the principle underlying hasty generalization.

For example: “My roommate said her philosophy class was hard, and the one I’m in is hard, too. All philosophy classes must be hard!” Two people’s experiences are, in this case, not enough on which to base a conclusion.

  • Red Herring: introducing an irrelevant or secondary subject and thereby diverting attention from the main subject.

For example, “airbags in cars do not really increase safety, and, besides, most cars with air bags are Japanese imports. We all know that foreigners cannot be trusted.”

  • Straw Man: distorting an opposing view so that it is easy to refute.

For example, “Vote against gun control, since gun control advocates believe that no one should own any type of firearm.”

  • Non Sequitur: drawing a conclusion that does not follow from the evidence.

For example, “My shoe string broke; I guess that means it’s time to buy a new car.”

  • Post Hoc (Faulty Causality): inferring a causal connection based on mere correlation.

For example, “Murder rates correlate with ice cream sales, therefore eating ice cream makes people homicidal.”

  • False Dilemma/Dichotomy: an argument that suggests only two possible alternatives, neither of which are typically very appealing. In fact, many other alternatives may exist.

For example, “To stop the spread of AIDS we must either quarantine all infected people or ban same sex marriage. Since the first option is clearly impossible, we should make same sex marriage illegal.”

Note that this also commits a straw man fallacy and a bit of a red herring. It is possible for an arguer to use more than one fallacy at a time.

  • Slippery Slope: a string of “if-then” statements that form what may seem like a valid argument, but typically draw a conclusion that predicts unfounded dire consequences.

For example, “If we don’t stop the Communists in South Vietnam, they’ll take over the whole country. If they take over Vietnam, next they’ll conquer Laos, Cambodia, and Thailand. Once they have Laos, Cambodia, and Thailand – they’ll overrun Indonesia and the rest of the Pacific Rim. Once they conquer the Pacific Rim, they’ll take Japan –and the next thing you know, they’ll be off the coast of California!The implicit conclusion here is that if we don’t stop the North Vietnamese from invading South Vietnam, America will become communist.” 

A Tip For Finding Fallacies

When writing your own essays, you have an obligation to be an ethical, credible source. In order to be credible and avoid fallacies, make sure to research all sides of the argument, be ready to explain any generalizations (especially broad ones such as “All Catholics believe…”), list your claims and the evidence you have for each claim, and double check to ensure you fairly characterize the views of others.

Michael | 2019

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