A Gentle Introduction to Fallacies

Esperanto ▪ English
May 1, 2016
Last updated: March 9, 2019

Learning is not compulsory; neither is survival.
―W. Edwards Deming


Table of contents


Fallacies are errors in reasoning, made in the construction of arguments. Some are committed intentionally to manipulate and deceive, while some are committed unintentionally due to ignorance and recklessness. Fallacies are divided into two kinds—formal and informal. Formal fallacies, also called logical fallacies, are expressed in a system like propositional logic. Informal fallacies are errors in the content of the premises.

In this post I’ll briefly go through some of the common fallacies encountered in our daily lives. Some are hidden in plain sight while some creep into the corners and require a closer examination.

Post hoc ergo propter hoc

After X, Y happened. Therefore, X caused Y. When an event happened after another event, it is presumed that what happened before it must have caused it.

“After Juana communed to Jibbers Crabst, her father recovered from his illness. Praise Jibbers Crabst!”

This is fallacious because she ignores the possibility that it may have been the medications given to her father, that made him well.

Cum hoc ergo propter hoc

During X, Y happened. Therefore, X is related Y. When an event happened together with another event, it is presumed that what happened with it must be relevant.

“Oh my! Did you know that when I was moving here to New York, Cubao, Pedro was doing so, too! Our minds must be connected by astral forces!”

This is fallacious because she doesn’t consider other factors like Pedro moving to that city because of his own volition, and not due to magic.

Ad hominem

This happens when instead of presenting a case against an argument, person A is instead attacked personally, by person B. This is done to discredit the person A, based on who he is, and not the argument that he holds.

After Maria presented a compelling evidence on the failures of democracy, Juan objected that we shouldn’t believe anything from a woman who isn’t married, doesn’t have kids, and listens to weird music.

Maria’s personal status doesn’t not have any bearing on the validity her claims. Juan’s statements are irrelevant. What should be attacked is Maria’s argument, and not her personal standings.

Tu quoque

This is committed when a person’s argument are claimed to be false because that person is inconsistent with his words. This fallacy is also known as the “You, too” fallacy.

Doctor: “Quit smoking because it is harmful to your health.”
Patient: “You, yourself smoke, so I can’t follow your advice.”

The patient rendered the doctor’s statement to be invalid, because the doctor smokes, too. If the patient presented an objection that smoking is not harmful to the health, then it would have been a better position.

Loaded question

This happens when a presumption is made beforehand, and that an answer is forced from constrained choices, like “yes” or “no”.

“Juan, have you stopped cheating on your wife?”

This is fallacious because the speaker assumes that Juan has cheated, at least once on his wife. If Juan answers “Yes.”, then he has cheated on his wife before, and that he has already stopped. If Juan answers “No.”, then he has cheated before, and still continues to cheat on her.

False dichotomy

This is committed when a person is forced to choose a position, or answer a question, with coerced limits. This is also called the black-and-white, or the either-or fallacy.

“Either you’re with me or you’re against me.”

This is fallacious because it presents extreme positions, even if there are other positions aside from those presented. In this case, the person being asked may be indifferent to the positions of the speaker.

False compromise

This is committed when a gray area is forced, even if there are clear choices. This is usually observed in journalism to provide an “equal” and “unbiased” coverage.

“Everyone in this table is bound to their individual opinions. Nobody is necessarily right or wrong.”

The speaker avoids the discussion and the determination of the plausibility that one or more arguments may be the solution to the problem. This is done to commit “fence sitting” and to “play it safe.”

Hasty generalization

This is committed when it is assumed that a part composes the whole. It is made when a conclusion is drawn from a sample that is not large enough.

“I was molested in childhood by a homosexual. Thus, homosexuals are vile creatures, and they must be punished!”

The speaker assumed that just because he experienced one such incident in his life before, he concluded that all homosexuals are despicable, and that they must be treated with contempt and disgust.

Sweeping generalization

This is committed when a majority is assumed to compose the whole. It is made when a significant percentage is applied to the entire composition.

“In all of the stores that I’ve gone to, there’s not a single one that sells a blue-tipped Super Panda pen. That means, I won’t be able to find such a pen in the whole country.”

The speaker has given up the possibility that such a pen may exist, in one or more of the stores that he hasn’t visited, yet.

Burden of proof

This is committed when the responsibility to provide proof does not lie with person A, the one making claims, but with person B, to disprove the claims of person A.

“Since you can’t prove the inexistence of a large cockroach that defecates stars and lives exactly 100,000 light-years away from where I’m facing right now, it must exist.”

Instead of providing evidence to his own claims, person A shifts the burden of providing proof to person B. Since there are no physical ways for person B to prove that the claims of person A is invalid, person A presumes that his claims must be true.

Slippery slope

This is committed when something is presumed to happen next, due to another factor. That, if you allow X to happen, Y will follow suit. Therefore, X should not happen.

“If we ban the use of firearms for civilians, then crime rate will increase because there’ll be nothing that civilians can use to protect themselves.”

This fails to consider that majority of gun-related accidents happen in the homes of their own owners. This also assumes that civilians who own guns are responsible enough to wield such weapons.

Red herring

This is committed when an irrelevant topic is introduced to divert attention from the original argument. The “red herring” is injected, under the pretense that it is relevant to the original topic.

Reporter: “How do you plan addressing the issues about corruption?”
Candidate: “I’m going to give everyone a job, and I’m going to lower income taxes.”

The goal is to abandon the original topic, to distract the listener. This is frequently observed in political interviews and discussions.

Straw man

This is committed when person B presents a distorted, weaker version of the argument that person A holds. Person B then attacks this weaker version, and if triumphant, concludes that person A’s argument is defeated.

Juan: “Alcohol ads should be banned from mass media, because it indirectly encourages underage drinking.”
Pedro: “People have been drinking alcohol for a long time. They will continue to do so.”

Pedro misrepresents the position of Juan as: “People should give up drinking alcohol.” That is not what Juan said.

Appeal to age

This is committed when it is argued that very old or very young arguments are superior. This is frequently seen in marketing and advertising.

“Our new and improved Super Bubbly Detergent Zet washes stain off better than the leading products.”

This fails to address why their products are superior to the others. Just because something is old or new, doesn’t make it better.

Appeal to seniority

This is committed when a person’s age is used to support the validity of his claims. This is usually applied against someone who is younger.

“I’ve been in the business for 30 years. You’re only 30, what do you know about programming language design?”

It is assumed here, that just because someone is younger than him, makes him less qualified for the things that are being discussed.

Appeal to authority

This is committed when the actions, choices, and words of a person of authority, or expertise, is used to disprove the claims of another person.

“The theory of evolution is wrong, because Kulas, who is a scientist, said that he doesn’t believe in it.”

Just because someone is a scientist, doesn’t mean that he supports the theory of evolution. It is likely that even if he is a scientist, he doesn’t understand the said theory.

Appeal to anonymous authority

This is committed when an appeal to authority is made, but the authority is not named. This makes it very difficult to verify the validity of the claims.

“Experts agree that drinking a glass of Meh Juice everyday will make you healthier.”

This fails because of the failure to specify who these so-called experts are. When asked to specify who these experts are, he will resort to tactics to elude the question.

Appeal to false authority

This is committed when an appeal to authority is made, but the authority in question is outside the scope of his expertise.

“Pedro extensively studied and reviewed the efficacy of Kidneyaid Capsules, and asserted that they indeed improve kidney health.”

Pedro, however, is not qualified professional to study and review health products, nor does he have any substantial experience prior to conducting such a study.

Appeal to popularity

This fallacy states that if most people—relative to the speaker—chooses a specific position, then that position must be true. The basic idea is that a claim must be accepted as true on the grounds that people are favorable towards that claim.

“The survey shows that most people are going to vote Juan for president. Their choice must be correct. I’m going to vote for him, too.”

This happens when a person believes a claim on superficial bases. This usually happens due to biases. A choice is made not due to technical merits, but due to prejudices.

Appeal to nature

This fallacy is committed when it is argued that just because something is “natural” means it is ideal or good.

“Juana claims that if a product is not labeled ‘organic’ or ‘natural’, then it is not ideal for consumption.”

Cultivated tobacco (Nicotiana tabacum) is a naturally-occuring plant that is responsible for more than five million deaths per year, around the world. Cyanide, one of the most toxic substances, occurs naturally.

Appeal to emotion

This fallacy is committed when emotions are used to elicit a fallacious response from the target. The basic idea is that emotional tactics are used to persuade a person into believing that the argument being presented is valid.

“Pedro, eat your broccoli. Think about all the poor, starving, and homeless children around the world.”

Pedro’s parent wants to make him eat the broccoli, by using emotional ploy, instead of providing substantial reasons for Pedro to eat the broccoli.

Appeal to force

This fallacy is committed when the threat of force or violence is used to coerce a person to accept a claim to be true. This fallacy is very common in religious circles.

“If you don’t listen to the words of Jibbers Crabst, you’ll burn in the torturous flames of Kell.”

Instead of providing a reason why someone should listen to Jibbers Crabst, threats of violence are instead used to force someone to follow blindly.

Appeal to tradition

This fallacy is committed when it is argued that just because something is traditional, or the norm, then it must be followed. This is found in religion and cultures.

“It is customary for us to participate annually in the Kabobohan March. You should join us, too.”

This fails to state why one should join the said event. Instead it is argued that it should be done on the grounds that it is traditional.

Appeal to origins

This is committed when it is assumed that an argument or a speaker, of a particular origin has more bearing or significance. This is usually observed in social classes, biological lineage, and cultures.

“Given that Pancho comes from a poor family, when he gets elected as the president, I’m sure he’ll be able to help the poor like us.”

This presumes that since Pancho originates from less fortunate social standings, he will favor the ones who are also poor, just like he was before.

Appeal to the future

This is committed when a person uses the uncertainty of the future, to support his argument. He asserts that in the future, his claims will eventually become true.

“Nobody does it yet, but I’m sure in the future, everyone will.”

There are no known ways at the moment, to verify his claims, since it is impossible to see or experience the future.

Appeal to complexity

This is committed when a person will assert that just because he doesn’t understand something, then it means that most people doesn’t, too.

“I still can’t understand lambda calculus after all these years. Heh. Chances are, nobody really can.”

The speaker applies his personal limitations to everyone, since he himself can’t do it. This is similar to hasty generalizations.

Appeal to balance

This is committed when the idea of balance is used when it is not appropriate. The word “balance” in these contexts is ill-defined, and may have multiple ambiguous interpretations.

“There must be chaos and discord to create balance in the universe.”

It is unclear what kind of balance does the speaker speak of. When asked, he fails to explain why such is necessary. He further argues that since wars and terrorism are inevitable, then they must exist to create balance. This is faulty reasoning—just because you can’t eliminate the undesirable, doesn’t mean that its existence is necessary.

Begging the question

This fallacy is committed when the thing to be proved is used as one of the premises. It is an example of circular reasoning.

“The divine words of Jibbers Crabst are pure, splendid, and impeccable because it says so in The Eternal and Transcendent Book of Crabst.”

This blatantly assumes the validity of the existence of such an entity, and to prove it means to assume that that entity exists, first. X because X.

Selective observation

This is committed when a conclusion is made from narrow and limited views. This is also called the cherry picking fallacy. Mass and social media is notorious of this.

“Juana is living a blissful and satisfying life because I frequently see her posts on socia reto that she is happy.”

The observer ignores the possibility that what he sees may not be true because Juana only posts what she wants people to see and believe.

No true Scotsman

This is committed when an argument is made by asserting that a behavior is only acceptable within the confines of certain standards.

“Why don’t you eat with your bare hands? A true Kilikilimo should eat with his bare hands!”

This is a form of false purity. It asserts that there is only one acceptable way for a Kilikilimo to eat. This is similar to appeal to tradition.

Not invented here

This is committed when something that is foreign or local, is deemed worse or better. This is observed in social classes, cultures, traditions, race, and gender.

“What does Juan know about feminism? He’s a man!”

This argues that just because Juan is a man, means that he doesn’t know how to support the ideologies of feminism. This is also frequently observed with imported products, claiming that they’re superior over the local ones just because they’re “imported.”


This is committed when an idea is rejected but it is not explained why. This is usually done when a person doesn’t like an idea, and he will resort to forceful dismissal of an argument.

“Since you openly object to democracy, you better leave the country and find one that fits your tastes!”

The speaker doesn’t state and explain his objections, and uses a shallow verse for giving such a statement. He is uncomfortable with the objections, and a way for him to get around this discomfort is to remove the originator of such objections.

Bad analogy

This is committed when the speaker argues that since two things are similar in some characteristics, then it follows that they must share other characteristics.

“When you mix coffee, sugar, and milk with a spoon, it spins, and it creates something new—a tasty drink. The solar system spins, too. If the celestial bodies around the Sun spin fast enough, something like that must be created, too.”

The speaker convolutes something that is directly observable, to something that is inobservable, and draws conclusions based on false comparisons.

Diminished claim

This is committed when a speaker asserts something, but retracts it later by providing contradictory statements. This is also called “Having your cake.”

“Look son, I don’t believe in ghosts. Last night, however, when I was alone in my room, I heard tapping sounds on the night stand. I’m sure it wasn’t me. It must be those unseen astral beings.”

The speaker makes a bold statement about not believing in the paranormal existence of ghosts, but he backs out later and claims that some “astral” beings must be the source of the tapping. He claims X but states the anti-X, later.

Least plausible hypothesis

This is committed when a person blatantly ignores compelling and sound evidence, in favor of a convoluted one that raises even more questions.

“The statue of virgin Mary in the hills of Idyay cried tears of blood. She must be weeping because of all the sins that mankind is creating.”

The spectators were very willing to accept the idea that that statue was indeed weeping what they thought was “divine” blood. It was later discovered that a tube was connected, via a conduit, and cow blood was pumped through it.

Moving the goalpost

This is committed when person B changes his position after person A successfully attacks the initial position of person B. The goal is to move the goalpost so that it will then be difficult for person A to attack the new, shifted post.

Pedro claimed that it is due to his daily intake of Kidneyaid capsules that makes his kidney healthy. When he was diagnosed with kidney stones, he stated that it could have been worse, had it not been for his Kidneyaid capsules.

The speaker adjusted his position when his initial claims were jeopardized. When the situation has changed, the speaker changed his position, too.

Poisoning the well

This is committed when person B objects that one or all of the sources of person A is invalid and unusable, thus rendering the argument of person A unacceptable.

“One of the sources of your paper is a report made by a well-known plagiarist. This renders your proposals invalid and we’re not going to accept it.”

Presuming that the source information is indeed invalid, it doesn’t render the argument that person A is presenting to be invalid, too. This is related to appeal to origins.

Closing remarks

I hope that with this post, I was able to add more thinking clarity.

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