Informal Fallacies

Fallacies in General

All fallacies are non sequiturs. “Non sequitur” is latin for “it does not follow.” You don’t need to remember the many types of fallacies if you’re good at figuring out that a conclusion doesn’t follow from its premise(s). However, you may find it useful to think about the different types of fallacies.


Fallacies of Relevance

Fallacies of Weak Induction

Fallacies of Presumption

Fallacies of Ambiguity

Fallacies of Grammatical Analogy


Fallacies of Relevance

Arguments in which these occur have premises that are logically irrelevant to the conclusion.*

Accident

This fallacy is committed when a general rule is applied to a specific case it was not intended to cover.* Note: This fallacy is similar to the fallacy of division.

Examples
  • “It’s good to spread knowledge. Gossiping is a way to spread knowledge. Therefore, it’s good to gossip.”
  • “It’s wrong to kill; therefore, you should not kill termites in your home.”

Share

Appeal to Force

(Argumentum ad Baculum)
This fallacy occurs whenever an arguer poses a conclusion to another person and tells that person either implicitly or explicitly that some harm will come to them if they do not accept the conclusion.*

Examples
  • “If you don’t download and install McAfee, you’re leaving yourself wide open to malware.”
  • “If we surrender, the enemy will take the chance to slaughter us all.”
  • Secretary to boss: “I deserve a raise in salary for the coming year. After all, you know how friendly I am with your wife, and I’m sure you wouldn’t want her to find out what’s been going on between you and that sexpot client of yours.”

Share

Appeal to Pity

(Argumentum ad Misericordiam)
This fallacy occurs when an arguer attempts to support a conclusion by merely evoking pity from the reader or listener.*

Examples
  • “Suzy should get the promotion because she has 17 kids to feed.”
  • “Jurors, look at this miserable man in a wheelchair, unable to use his legs. Could such a man really be guilty of embezzlement?”

Share

Appeal to the People

(Argumentum ad Populum)
This fallacy uses the desires of people to be loved, esteemed, admired, valued, recognized, and accepted by others to get the reader or listener to accept a conclusion.*

Examples
  • Direct

    “Ladies and gentlemen, today the lines of battle have been drawn. When the din of clashing armor has finally died away, the Freedom Party will emerge victorious! We are the true party of the American people! We embody the values that all real Americans hold sacred! We cherish and protect our founding fathers’ vision that gave birth to the Constitution! We stand for decency and righteousness, for self-determination and the liberty to conduct our affairs as each of us freely chooses! In the face of our standard bearing the American eagle of freedom, our muddle-headed, weak-kneed opponents with their collectivist mentalities and their deluded programs for social reform will buckle and collapse! Victory will be ours, so help us God!”

  • Indirect — Bandwagon

    “Tens of millions of people voted for Caligula; therefore, Caligula will be a great leader.”

  • Indirect — Appeal to Vanity

    “A beautiful, intelligent person like you will naturally see the correctness of my argument.”

  • Indirect — Appeal to Snobbery

    “Only unsophisticated people drink that type of wine.”

Share

Argument Against the Person

(Ad Hominem)

Ad Hominem: Abusive

In this version, the second person responds to the first person’s argument by verbally abusing the first person.*

Examples
  • “Nietzsche’s philosophy is not worth the paper it’s printed on. Nietzsche was an immoral reprobate who went completely insane from syphilis before he died.”
  • “Why would you listen to the NRA? They’re just a bunch of ignorant yokels.”

Share

Ad Hominem: Circumstantial

This version begins the same way as the ad hominem abusive, but instead of heaping verbal abuse on his or her opponent, the respondent attempts to discredit the opponent’s argument by alluding to certain circumstances that affect the opponent.*

Examples
  • “Stacey is only arguing in favor of minimum wage because, if the minimum wage is increased, then her own salary will go up. Obviously her arguments are worthless.”
  • “The congresswoman argues that we should open up the Arctic National Wildlife Refuge for oil drilling. But she just wants to reward her rich cronies in the oil industry who got her elected. Therefore, we can hardly take her arguments seriously.”

Share

Ad Hominem: You Too

(Tu Quoque)
The tu quoque (“you too”) fallacy begins the same way as the other two varieties of the ad hominem argument, except that the second arguer attempts to make the first appear to be hypocritical or arguing in bad faith.*

Examples
  • “Political operative Newt Gingrich has argued about the need to preserve family values. But who is he to talk? Gingrich has been married three times. He divorced his first wife while she was hospitalized for cancer, and he engaged in an extramarital affair while he was married to his second wife. Clearly, Gingrich’s arguments are trash.”*
  • “How can you possibly argue against smoking when you are a smoker yourself?”

Share

Genetic Fallacy

This fallacy occurs when an arguer evaluates a thing in terms of its earlier context, ignoring relevant changes that may have altered its character in the interim and then uses that evaluation to support a conclusion in the present.*

Examples

  • “I will never get married. Did you know that the word ‘wife’ originally referred to those women who were captured, after the invasion and conquest of a neighboring tribe, and brought home to be slaves? Marriage was a degradation!”*
  • “The Freedom Party says that we need to keep women out of the workforce. The party has a long history of sexism, though, so we can just disregard this.”
  • “You apologize? Well, since the word ‘apology’ comes from the Greek word for ‘defense,’ I can only assume that you are trying to defend your despicable behavior.”*
  • “I will not vote for Schroeder. Everyone knows she is German, and we all know German history. No anti-Semitic candidates for me!”*
  • There is no way we should support eugenics! That idea was advocated by the Nazis in Hitler’s Germany, don’t forget!*

Share

Missing the Point

(Ignoratio Elenchi)
This fallacy occurs when the premises of an argument support one particular conclusion, but then a different conclusion, often vaguely related to the correct conclusion, is drawn.*

Examples
  • “Abuse of the welfare system is rampant nowadays. Our only alternative is to abolish the system altogether.”
  • “Mr. Rhodes is suffering from amnesia and has no recollection whatever of the events of the past two weeks. We can only conclude that he did not commit the crime of murdering his wife a week ago, as he has been accused of doing.”

Share

Red Herring

The red herring fallacy is committed when the arguer diverts the attention of the reader or listener by changing the subject to a different but sometimes subtly related one.*

Examples
  • “You say that our animal shelter’s ad campaign is offensive, but you forget that our shelter has saved thousands of animals and has protected the health of the general public for decades.”*
  • “There is a good deal of talk these days about the need to eliminate pesticides from our fruits and vegetables. But many of these foods are essential to our health. Carrots are an excellent source of vitamin A, broccoli is rich in iron, and oranges and grapefruit have lots of vitamin C.”*

Share

Straw Man

The straw man fallacy is committed when an arguer distorts an opponent’s argument for the purpose of more easily attacking it, demolishes the distorted argument, and then concludes that the opponent’s real argument has been demolished.*

Examples
  • “Senator Barrow advocates increased Social Security benefits for the poor. It is regrettable that the senator finds it necessary to advocate socialism. Socialism defeats initiative, takes away promised rewards, and leads directly to inefficiency and big government. It was tried for years in Eastern Europe, and it failed miserably. Clearly, socialism is no good.”

Share


Fallacies of Weak Induction

This fallacy occurs not because the premises are logically irrelevant to the conclusion, as is the case with the eight fallacies of relevance, but because the connection between premises and conclusion is not strong enough to support the conclusion.*
Share

Appeal to Unqualified Authority

(Argumentum ad Verecundiam)
This fallacy is a variety of the argument from authority and occurs when the cited authority or witness lacks credibility.*

Examples
  • “Steve Jobs said that George W. Bush was one of the greatest painters of all time, so Bush really must be great.”
  • “Tiger Woods says that Preparation H is the best hemorrhoid cream, so it must be true.”

Share

Appeal to Ignorance

(Argumentum ad Ignorantiam)
This fallacy is committed when the premises of an argument state that nothing has been proved one way or the other about something, and the conclusion then makes a definite assertion about that thing.*

Examples
  • “People have been trying for centuries to provide conclusive evidence for the claims of astrology, and no one has ever succeeded. Therefore, we must conclude that astrology is a lot of nonsense.”
  • “People have been trying for centuries to disprove the claims of astrology, and no one has ever succeeded. Therefore, we must conclude that the claims of astrology are true.”

Share

Hasty Generalization

This fallacy occurs when there is a reasonable likelihood that the sample is not representative of the group. Such a likelihood may arise if the sample is either too small or not randomly selected.* Note: This fallacy is very similar to the fallacy of composition.

Examples
  • “Bernie Madoff was a crook; therefore, all financial managers are crooks.”
  • “It is wrong to kill; therefore, war can never be just because people are killed during war.”
  • “Some conservatives wish to ban gay marriage, discredit climate change, and deny evolution. Therefore all conservatives are homophobic, anti-environmental creationists.”
  • “Several recent terrorist attacks have been carried out by radical Islamic groups. Therefore all Muslims are terrorists.”
  • Anecdotal Evidence: “Yeah, I’ve read the health warnings on those cigarette packs and I know about all that health research, but my brother smokes, and he says he’s never been sick a day in his life, so I know smoking can’t really hurt you.”*

Share

False Cause

This fallacy occurs whenever the link between premises and conclusion depends on some imagined causal connection that probably does not exist.*

Examples
  • “My dirty underwear are lucky. I’ve worn them every day for the past year and the sun has continued to rise.”
  • “If vaccines don’t cause autism, why do so many kids get autism after getting vaccinated?”

Share

Perfectionist Fallacy

This fallacy is committed when one says that a proposal or claim should be rejected solely because it doesn’t solve the problem perfectly, in cases where perfection isn’t really required.

Examples
  • “You said hiring a house cleaner would solve our cleaning problems because we both have full-time jobs. Now, look what happened: every week, after cleaning the toaster oven, our house cleaner leaves it unplugged. I should never have listened to you about hiring a house cleaner.”*
  • “What’s the point of campaigns against drunk driving? People are going to do it no matter what.”
  • “World leaders’ plans to reduce carbon emissions by 20% by a certain date won’t solve climate issues completely. Therefore, we should reject such proposals completely.”*

Share

Slippery Slope

This fallacy is a variety of the false cause fallacy. It occurs when the conclusion of an argument rests on an alleged chain reaction and there is not sufficient reason to think that the chain reaction will actually take place.*

Examples
  • “The legalization of drugs will eventually lead to the total collapse of civilization.”
  • “The legalization of prostitution will eventually lead to the total collapse of civilization”

Share

Weak Analogy

The fallacy of weak analogy is committed when the analogy is not strong enough to support the conclusion that is drawn.*

Examples
  • “Guns are like hammers—they’re both tools with metal parts that could be used to kill someone. And yet it would be ridiculous to restrict the purchase of hammers—so restrictions on purchasing guns are equally ridiculous.”*
  • “People who have to have a cup of coffee every morning before they can function have no less a problem than alcoholics who have to have their alcohol each day to sustain them.”*

Share


Fallacies of Presumption

These fallacies arise not because the premises are irrelevant to the conclusion or provide insufficient reason for believing the conclusion but because the premises presume what they purport to prove.*

Begging the Question

(petitio principii)
This fallacy is committed whenever the arguer creates the illusion that inadequate premises provide adequate support for the conclusion by leaving out a possibly false (shaky) key premise, by restating a possibly false premise as the conclusion, or by reasoning in a circle.*

Examples
  • “I know the Bible is divinely inspired because 2 Timothy 3:16 says, ‘All Scripture is inspired by God.’ ”*
  • “Celibacy is an unnatural and unhealthy practice, since it is neither natural nor healthy to exclude sexual activity from one’s life.”*

Share

Complex Question

This fallacy is committed when two (or more) questions are asked in the guise of a single question and a single answer is then given to both of them.*

Examples
  • “Have you stopped cheating on your spouse?”
  • “How long do I have to put up with your bad behavior?”

Share

False Dichotomy

This fallacy is committed when a disjunctive (“either/or”) premise presents two unlikely alternatives as if they were the only ones available, and the arguer then eliminates the undesirable alternative, leaving the desirable one as the conclusion.*

Examples
  • “America: Love it or leave it.”*
  • “Since there is nothing good on TV tonight, I will just have to get drunk.”*

Share

Suppressed Evidence

This fallacy is committed when an inductive argument ignores some important piece of evidence.*

Examples
  • “Most dogs are friendly and pose no threat to people who pet them; therefore, it would be safe to pet the little dog that is approaching us now which is foaming at the mouth.”
  • “The Patriot missile is an excellent weapon. Tests show that in 98% of firings, the missile successfully left the launch pad.”
    (This is technically true. However, this omits the fact that, after leaving the launch pad successfully, a majority of the missiles either blew up in mid-air or failed to hit the targets.)*

Share


Fallacies of Ambiguity

Equivocation

The fallacy of equivocation occurs when the conclusion of an argument depends on the fact that a word or phrase is used, either explicitly or implicitly, in two different senses in the argument.*

Examples
  • “If we were going to push for an election, then we should have made sure that we did something to determine who was going to win.” (It’s unclear if the speaker wanted to intervene in the election process or simply study the election process.)
  • “The laws imply lawgivers. There are laws in nature. Therefore, there must be a cosmic lawgiver.”

Share

Amphibole

The fallacy of amphiboly occurs when the arguer misinterprets an ambiguous statement and then draws a conclusion based on this faulty interpretation.*

Examples
  • “Don’t kill yourself; let the church help.”
  • “Her parents watered the flowers, yet they died.”

Share


Fallacies of Grammatical Analogy

Composition

The fallacy of composition is committed when the conclusion of an argument depends on the erroneous transference of an attribute from the parts of something onto the whole.* This fallacy is so similar to the hasty generalization that I’m not sure the distinction matters. If you want to explore the distinction more, I recommend this.

Examples
  • “My new car has a great engine; therefore, it’s a great car.”
  • “Each player on this basketball team is an excellent athlete; therefore, the team as a whole is excellent.”

Share

Division

The fallacy is committed when the conclusion of an argument depends on the erroneous transference of an attribute from a whole (or a class) onto its parts (or members).* Note: This fallacy is similar to the fallacy of accident.

Examples
  • “Salt is a nonpoisonous compound; therefore, its component elements, sodium and chlorine, are nonpoisonous.”
  • “This airplane was made in Seattle; therefore, every component part of this airplane was made in Seattle.”
  • The average American family has 2.5 children. The Jones family is an average American family. Therefore, the Jones family has 2.5 children.”*

Share