How to Recognize a Logical Fallacy — Part 1

Reasoned, civil discourse is increasingly a thing of the past. Rather than analyze disagreements through some rational filter, social media seems to encourage the debate strategy of screaming loud enough to drown out any competing view.

One of the most common methods of debate is the use of a logical fallacy. A logical fallacy is a hiccup in reasoning where the conclusion may seem convincing, but the basis for the conclusion took a wrong turn. The best way to guard against being led astray by logical fallacies is to recognize them.

In an effort to restore some civility in our discourse and to combat pervasive ignorance, we offer Part One of this quick primer on how to recognize the most common logical fallacies.

Ad Hominem

“Ad hominem” is Latin for “against the man.” It is the strategy of trying to win an argument by attacking the person who holds the opposing view in a way that has nothing to do with the truth of the matter being asserted.

It looks something like this:

  • Person A: “We know that the world is not flat because its shape can clearly be seen from space, the physics of orbital dynamics would not work to keep satellites aloft if the earth were flat, and people have travelled around the world many times, but no one has ever seen the edge of a flat disc-shaped world.”
  • Person B: “Your reasoning is fundamentally flawed because anyone with a mother as ugly as yours has to be an idiot of cosmic proportions.”

More than just an insult, an ad hominem attempts to sidestep the merits of a claim by refocusing attention on a person’s personality, appearance, fashion sense, or any other irrelevant feature.

Appeal to Authority (argumentum ad verecundiam)

When trying to prove your point, it is good to cite authorities that support your position. This is different from the fallacy of appealing to authority. An appeal to authority is basically a reliance on an improper authority or avoidance of a reliable but inconvenient authority.

This can be a difficult one to identify. If a debater quotes Dr. Phil in support of a position, it may be a valid point if it is within the area of Dr. Phil’s expertise (clinical psychology). If Dr. Phil’s comments are intended to bolster a position relating to quantum physics, it probably constitutes the fallacy of appeal to authority.

Elmo testifies before Congress in 2002.

It can also occur when a person intentionally steers away from reliable authorities. Congressional hearings are notorious for inviting noted Hollywood celebrities to bring testimony about a particular issue. Most of the time, the extent of the celebrity’s expertise comes from having starred in a movie in which the subject matter under discussion was featured. Because of that individual’s celebrity status, undue attention and weight is placed upon that person’s opinion, instead of someone who is truly an expert. In 2002, for example, the Muppet Elmo testified before the House Education Appropriations Subcommittee to urge more funding for music research and music education in schools. While the committee heard from others in support of this measure, few witnesses remember anyone other than Elmo.

An appeal to authority is, at its essence, a request to simply take someone’s word for it on the basis of their fame. If there is nothing other than name recognition to bolster an “authority’s” assertion, his or her opinion should be treated as irrelevant.

It should be noted that appeal to authority is the basis for almost all celebrity endorsements. When a professional athlete appears on an advertisement in support of a product, the unstated assumption is that if a big celebrity like that uses a product, then the product must be good. This might be true if the celebrity is Chef Gordon Ramsey and the product is a fancy line of cutlery. In the case of actor Brad Pitt endorsing Lenovo computers, however, his expertise in this particular field has yet to be universally accepted.

Appeal to Ignorance (argumentum ad ignorantiam)

On its face, using ignorance as the major premise to bolster an argument should negate the validity of the argument. In practice, an appeal to ignorance is used successfully on a regular basis to sway opinion.

An appeal to ignorance is the practice of pointing to the absence of proof as proof of the premise. It not only is a bad basis for proof, but the same principle of ignorance can be used to “prove” conflicting premises. For example:

  • “No one has ever been able to prove that Big Foot does not exist, therefore he must be real.”
  • “No one has ever been able to prove that Big Foot does not exist, therefore he must not be real.”

If the same argument strategy can support mutually exclusive claims, then it’s not a good argument strategy. All that it accomplishes, after all, establishing that the individual doesn’t know something. That’s a far cry from proving anything else.

Appeal to Pity (argumentum ad misericordiam)

“Argumentum ad misericordiam” is Latin for “argument to compassion.” It attempts to bypass relevant matters by tugging on the heartstrings of the hearer. It is a blatant attempt at emotional manipulation.

Consider, for example, a debate regarding the health benefits or lack thereof of eating meat. In support of the vegetarian position, an individual shows a picture of a young lamb and says, “Look how cute and cuddly this little guy is. How can you even consider killing such an adorable creature just so you can have a quick bite to eat?”

Strictly in terms of whether meat is good or bad for human health, that argument is irrelevant. Its sole purpose is to get the listener to pay attention with the heart, rather than the head.

This is the same strategy often employed by criminal defense attorneys. They make sure their clients are well groomed when appearing in court, and they will appeal to the sympathy of the jurors by talking about the difficulties the defendant has faced in life. While this may have value in terms of a sentencing hearing, it is rarely relevant in determining whether the person actually committed the crime.

Bandwagon Fallacy (ad populum)

The bandwagon fallacy may be one of the first ones any of us used. It likely happened when you pushed back against one of your parents’ rules by saying, “But all of my friends are doing it!” In all likelihood, the flaw in this argument was thrown back at you with the response, “If all you friends jumped off the top of the Empire State Building, would you do that, too?”

The basis for this argument assumes something is true or meritorious because other people agree with it or are doing it. It appeals to “herd mentality,” which is the tendency of people to adhere their beliefs and/or actions to what they perceive to be the consensus of those around them.

The fallacy draws its name from the political campaign practice of parading through the streets, attempting to draw a crowd. Those who supported the candidate were invited to jump on the bandwagon.

The biggest problem with the bandwagon fallacy is that broad consensus is not necessarily an indication of the validity of a position. For example, nearly every scientific breakthrough has defied the consensus of the scientific community. The fact that a majority of scientific minds had reached a particular conclusion did nothing to change facts that were ultimately discovered.

As St. Augustine famously said, “Right is right even if no one is doing it; wrong is wrong even if everyone is doing it.”

Causal Fallacy — False Cause (non causa pro causa)

There are two primary causal fallacies. The first is the false cause or non causa pro causa (“not the-cause for a cause”) fallacy. The is when you reach a conclusion about the cause of something without evidence to back it up. An example would be if you saw a guy wearing a leather jacket and thereby concluded that he must be a fan of the leather jacket-wearing character Fonzie on the television show “Happy Days.” That person may or may not be a fan of the show; the evidence is insufficient to draw that conclusion, however.

Causal Fallacy — Post Hoc (post hoc ergo propter hoc)

The other primary causal fallacy is known as post hoc. This is short for post hoc ergo propter hoc (“after this, therefore because of this”). This fallacy attributes one thing to be the cause of another simply because the one happened before the second.

The post hoc reasoning is used when you have a bad day and then conclude that everything bad that happened to you is because you chose to wear red shoes. Assuming, of course, that you can’t point to anything directly connected to your choice of footwear, it is wrong to jump to the conclusion that your misfortune is the result of what you have on your feet.

Circular Argument (petitio principii)

A circular argument occurs when the conclusion is simply a repeat of the premise. “My distinguished opponent is lying because he is a liar.” It does not arrive at any new conclusion and uses itself as the authority. It is essentially the same as citing yourself in a research paper or insisting that your position must be accurate because it is your position — something this writer most definitely did NOT do when he was editor of his undergraduate student newspaper.

Equivocation (ambiguity)

Equivocation happens when a word, phrase, or sentence is used deliberately to confuse, deceive, or mislead by sounding like it’s saying one thing but actually saying something else. Equivocation comes from the roots “equal” and “voice” and refers to two voices; a single word can “say” two different things. Another word for this is ambiguity.

Sir Humphrey Appleby uses equivocation in an episode of Yes, Prime Minister.

If someone employs this for comedic or creative purposes, it is called a “play on words.” When it is used during a debate, it serves the purpose of misdirecting the audience. When it’s poetic or comical, we call it a “play on words.” But when it’s done in a political speech, an ethics debate, or in an economics report, for example, and it’s done to make the audience think you’re saying something you’re not, that’s when it becomes a fallacy.

The use of equivocation was employed masterfully by Sir Humphrey Appleby in the television series Yes, Minister and Yes, Prime Minister. In one episode he justifies the Prime Minister’s flip-flopping on an issue with this convoluted explanation: “It is characteristic of all committee discussions and decisions that every member has a vivid recollection of them and that every member’s recollection of them differs violently from every other member’s recollection. Consequently we accept the convention that the official decisions are those and only those which have officially recorded in the minutes by the officials, from which it emerges with an elegant inevitability that any decision which has been officially reached will have been officially recorded in the minutes by the officials and any decision which is not recorded in the minutes has not been officially reached even if one or more members believe they can recollect it, so in this particular case if the decision had been officially reached it would have been officially recorded in the minutes by the officials. And it isn’t so it wasn’t.” (See the adjacent video.)

Sometimes, this is shows up not as a fallacy but as miscommunication. It becomes a fallacy, however, when it is intended to deceive. The deception is sometimes softened with euphemisms, replacing unpleasant words with “nicer” terminology. For example, a euphemism might be replacing “lying” with the phrase “ creative license, ” or replacing my “criminal background” with my “youthful indiscretions,” or replacing “fired from my job” with “taking early retirement.” When these replacement words are used to mislead people they become an equivocation fallacy.

Be sure to come back to Commonplace Fun Facts for the second part of this guide to logic.

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