Common Logical Fallacies

Over two-thousand years ago, Aristotle taught us that in order to be persuasive, we need to resonate with people on three levels: 

• 1. ethos -- they need to trust us or sense that we have authority

  2. pathos -- they need to feel something (anger, delight, sadness, despair, outrage, etc.)

  3. logos -- they need to see that our argument is logical or reasonable

When we do something along these three lines that works, we call it an appeal. For example, if I say, "I know what I'm talking about because I have a Ph.D. in rhetoric," and that makes you want to believe me, then that's an ethical appeal. That's why ethos, pathos, and logos are often referred to as rhetorical appeals, audience appeals, or Aristotle's appeals. 

When we do something along these three lines that doesn't work, we call it a fallacy. The words fallacy and fail have the same roots: a fallacy is a failure in our argument. So going back to my original example, if I say, "I know what I'm talking about because I have a Ph.D. in physics," and that makes you question my authority (what does a physicist know about rhetoric?), then it would be an ethical fallacy. 

This is important, so I'll reiterate: If it works, it's an appeal. If it doesn't work, it's a fallacy. And one-person's appeal could be another-person's fallacy. If I tell you a sad story in the hopes you give me money, and you find yourself pulling out some cash, then that would be considered a pathetic appeal. My sad story worked on you! If, however, you just roll your eyes and don't reach for your wallet, then it's a pathetic fallacy. Not only did my sad story not work, but it probably made you even less likely to give me cash. 

Whether it's an ethical, pathetic, or logical blunder we make, we usually just refer to them as logical fallacies. Here is a list of common logical fallacies. Sometimes people commit these fallacies on purpose, hoping no one notices (for example, when a politician tries to change the subject to get the attention off a tough question, we call that a red herring fallacy). But usually people commit these fallacies by mistake, and it can make their argument weak and easy to pick apart. It's important to understand these fallacies so that you can avoid making them in your own arguments, and so that you can point them out in other-people's arguments. 

As you read through these, you'll probably notice that these are familiar. We often understand bad logic at an instinctual level from a very young age. Rhetoricians have simply given a name to these things. What's important isn't that you memorize the proper name for each fallacy, but that you can recognize them when you see them. 

Note: Some of these examples are real (from conversations, articles, the radio, etc.), and some are made up. Don't get caught up in the details of where it came from or who said it. What's important is the logic undergirding each example and how it falls apart. 

Hasty Generalization: Making a claim about a whole group based on too-few examples.

“Californians are jerks. While I was driving to Disney Land, I got cut off by three people with California plates, and one of them even flipped me off.”

There are a few things wrong with this statement. First, it assumes that the drivers are actually from California, and there is no way to know that just from their plate. Second, if that many people are cutting you off and giving you the middle finger, then that tells me more about you as a driver than them. And third--this is where "hasty generalization" comes in--there are nearly 40 million people living in California. You can't conclude that all or most of them are jerks based on the actions of only three. 

“The iPhone 13 is terrible. I bought one last month and the screen cracked within a week.”

That's unfortunate, but how many millions more are out there without a cracked screen? If you can show me that the same thing happened to 150,000 other customers (which would be just 1 percent of the 15 million iPhone 13's that were sold), then I would be inclined to agree there is a problem. But I'm not convinced based on your one bad experience. (And, same as above, your cracked screen tells me more about you than the product.) 

This is also known as anecdotal evidence or anecdotal fallacy. If you refuse to go to Burger King ever again because one of the cashiers was mean to you, that doesn't mean that all Burger King employees are mean or that the company has a policy that encourages employees to be rude. Employees are human. They have bad days. You're bound to run into a grouchy cashier at any burger joint. So your boycott of Burger King is founded on the logical fallacy of hasty generalization or anecdotal evidence.

"But," you say, "my brother went to the other Burger King downtown and had a similar experience!" 

Well, no. There are over 18,000 Burger Kings in the world with 34,000 employees. Two bad experiences isn't enough to convince me to get my burger fix somewhere else.

Missing the Point: While your evidence is good, your conclusion is absurd or irrelevant. 

“Since most burglaries are committed by males after nightfall, the police department should institute a strict curfew for all males.”

The first part of the sentence is fine. It's absolutely true. Research shows that most burglaries, indeed, are committed by young men after nightfall. The last half of the sentence--the conclusion--is the problem. There are other more-reasonable conclusions to come to based on the data: the local police could increase night patrols, communities could organize neighborhood-watch associations, people could turn on porch lights and lock doors or invest in alarm systems. But instituting a curfew would just punish innocent young men and probably do nothing to deter the actual criminals. Good evidence--silly conclusion. 

“College students shouldn’t waste their time attending class. A 2019 PEW survey revealed that 52 percent of professors in the USA don’t even take attendance.” 

Even if it's true that most professors don't take attendance, there are other reasons to attend class--first of which would be so that you can actually learn something. Again: the facts might be sound, but the conclusion misses the point. 

False Cause (aka Post Hoc Ergo Propter Hoc):  Mistaking correlation for causation. Suggesting that two unrelated things are actually related and that one caused the other. 

“Isn’t it interesting how less than a year after Obama became president, Greece’s economy started to collapse?”

No. Not really. I heard this on the radio in 2009, but Greece's economic woes began decades before Obama became president. What could he really have done so early in his presidency to impact Greece's economy? Maybe if this radio host had made this claim a few years later, or if he pointed to specific policies or sanctions that the Whitehouse had instituted, then he might have had a reasonable argument. But that's not what the radio host was doing. He simply didn't like Obama and wanted to blame him for things well beyond his control. But that was common during those years. Car won't start? "Thanks, Obama." Girlfriend dumped you? "Thanks, Obama." Can't remember your Netflix password? "Thanks, Obama." 

This one seems too silly to even address because it's not likely anyone would believe there is any connection between dinosaurs and pizza. The claim is obviously a joke. It is common for people to purposely use a logical fallacy for comedic affect. This is what's known as a satirical argument.  

Chances are, you will dedicate a lot of time in college and your career trying to prove causation or correct people who are mistaking correlation for causation.  Scientists, lawyers, business analysts, and police officers (just to name a few) are in the business of proving causation. So it's important to know the difference between the two. 

Correlation: When two things happen that don't have anything to do with each other. They are coincidental. The Niners didn't lose the game because your brother wore the wrong shirt that day. And your mom didn't break her back because you accidentally stepped on a crack. Those are correlative relationships. Corporate lawyers representing an oil company might dedicate a lot of time and money trying to show that rising global temperatures and the burning of fossil fuels have nothing to do with each other. They hope to convince people it's a correlative relationship. Most scientists, on the other hand, are trying to prove that it's a causative relationship. 

Causation: When two things happen, and one was directly affected by the other. If I drop a book on the ground and one of my students immediately falls out of her chair and breaks her arm, my lawyer will argue that my dropping the book had nothing to do with the student's clumsiness. It's a correlative relationship. It was coincidence. Her lawyer, on the other hand, will try to show a causative relationship. It wasn't coincidence, and her client would not be injured had I not dropped the book and startled her. (Good thing I use an online textbook in real life...)

Slippery slope: The writer claims that doing one small thing will assuredly lead to some huge (and usually ridiculous) thing.

“If we make marijuana legal, then before we know it all street drugs will become legal and the whole country will be addicted.”

Nope. As far as I can tell, there hasn't been an uptick in crack usage in states that have legalized marijuana. If you have ever called out someone for exaggerating or being ridiculous, chances are they were using a slippery-slope fallacy. I suppose it could also be called the "well, that escalated quickly" fallacy. 

Remember the funny DirecTV commercials that suggested if you got regular cable, you would end up in a roadside ditch? Like the Woody's Pizza sign, they purposely committed a logical fallacy--in this case, slippery slope--for comedic affect. They knew that you knew it was a fallacy (no one really believed you would end up in a roadside ditch). You were in on the joke. That's what made it a satirical argument rather than a weak argument. 

Weak analogy: Trying to illustrate a point by comparing it to something completely dissimilar. Comparing apples to oranges.

“Parents would never let their toddlers play with a loaded gun, so why would they let them eat refined sugar and other processed substances that lead to obesity and diabetes?”

I have been in a room full of toddlers eating cookies. It was messy. But I've never been in a room full of toddlers holding handguns. I imagine it's not the same. 

"The new Microsoft Surface Pro is way better than a MacBook. It has a detachable keyboard and a touchscreen. The MacBook doesn't." 

This might be true, but the Surface Pro is a tablet, not a laptop. They should be comparing it to the iPad Pro. 

Ethical Fallacy (aka Appeal to Authority): Trying to get readers to agree with you simply by impressing them with a famous name or by appealing to a supposed authority who really isn't much of an expert.

“Reagan would never stand for the middle-grounding of today’s Republican Party.”

There are a few problems with this statement, but let's focus on the ethical fallacy at play: Reagan is dead, and we don't know what he would say. Invoking his name to postulate that he would approve or disapprove isn't sufficient to win the argument. If you could find a quote from Reagan about middle-grounding and show how it applies to what is happening today, then perhaps it would be an ethical appeal. But saying he would never stand for it is similar to saying "he would be rolling over in his grave," which just isn't as effective of an argument as some people might think. 

“Obesity affects more teens today than ever before. According to Ellen Degeneres, if we don’t discourage our children from eating fast food now, they’ll have major health problems as adults.” 

It would be an ethical appeal to cite Ellen on the topic of how to host a daytime talk show, or how to make it as a standup comedian, or a dozen of other great topics, but she isn't an expert on nutrition and obesity. I assume here she is paraphrasing a guest who was on her show--a doctor or nutritionist. It would be better to quote or paraphrase that expert--something like, "Dr. Cho, a nutritionist who specializes in childhood obesity, spoke with Ellen Degeneres recently about..." Or something. Cite the expert, not the person who had them on the show. 

Red Herring (aka changing the subject): Partway through an argument, the arguer goes off on a tangent, raising a side issue that distracts the audience from what's really at stake. Often, the arguer never returns to the original issue.

Red herring is a common political strategy (but still a logical fallacy), most often found when someone does something other than answer the question that was actually asked.  If you hear a politician say, "Great question," and then go off in a different direction, you've just been red-herringed. 

In Victoria England, hunters would attempt to spice up the sport, as well as identify which of their Beagle hounds were superior, by having someone drag a stinky fish across the trail. A good Beagle would keep pursuing the fox, while a less-effective Beagle would follow the fish smell and lose the fox altogether. Politicians, and anyone who throws you a red herring, wants you to do just the same—get lost long enough to forget what you were originally after!

Donald Trump is the master of the red herring. Early in his presidency, someone accused him of violating the emoluments act. That evening, this is what Trump tweeted. What do you think people were talking about the next morning? (Hint: it wasn't the emoluments act...) 

“Nobody should be allowed to burn the American flag - if they do, there must be consequences - perhaps loss of citizenship or year in jail!”

Band Wagon (aka Ad Populum): Appealing to the idea that if everyone agrees on something, it must be true. Also, appealing to the idea that the reader wants to be like everyone else.

“Since nearly half of the American population believes God created humans, creationism deserves equal attention in science textbooks. It can’t all be about Darwin and his monkeys.”

Regardless of how you feel about God or monkeys, the fallacy here is that a lot of people believing in something doesn't make it true. This happens a lot with surveys. People will often make a band-wagon fallacy when discussing the results. If I survey 100 students and 60 of them claim that I'm doing a great job as a professor, I haven't proven that I'm a great professor. I've simply shown that the majority of students think I'm doing a good job. But the university administration might have very different metrics (that my students don't know about) for evaluating my job performance. 

“Do you really want to be the only person in the office who opposes the new mandatory-overtime policy? It’s going to be approved no matter what, so you’re just going to make a fool of yourself. Why draw that kind of attention from the manager? You’re just painting a bullseye on your back.” 

This person's whole argument hinges on the band-wagon fallacy of "safety in numbers." In this sense, it kind of serves as a pathetic appeal as well: playing on people's fear of being singled out or not being supported by the group. 

Attack on the Person (aka Ad Hominem): Focusing on a person's looks or character rather than the issue at hand.  

“Why should we support a health bill endorsed by Senator Thompson, who is morbidly obese and chain smokes?”

I would want to actually read the health bill before making any conclusions. The senator's appearance and habits tell me nothing about what's in the actual bill, so pointing them out is just meanspirited. Also, perhaps Senator Thompson is motivated by his obesity and smoking habit to write a bill that would have helped him avoid those things in the first place. You can't judge a book by it's cover, nor can you judge a bill by the appearance of the senator who wrote it.  

“Governor Lee is an embarrassment to this state. Is that who we want representing us—some snaggle-toothed hillbilly who looks like he just got back from a possum hunt?"

Ouch. Makes me wonder what my students have to say about my long beard and love of flannel shirts. 

Trump to reporters after Hillary excused herself to use the restroom: "I know where she went, it's disgusting, I don't want to talk about it…No, it's too disgusting. Don't say it, it's disgusting."

Really? 

Pathetic Fallacy (aka Appeal to Pity): Relying too heavily on pathos (emotion) to make your argument.

“I know I missed a lot of assignments, but if you don’t give me an A in this class, I’ll be kicked off the team and lose my scholarship.”

Cue the violins. 

“Commissioner Wolfram has unsuccessfully run for the senate seven times in the last three decades. Isn’t it time we give him a break?”

Nope. There's probably a reason why he keeps losing. Let's focus on that. 

Appeal to Ignorance: Arguing that since there’s no conclusive evidence, the reader might as well accept your claim.

“How could we possibly know the inner-thoughts of our elected officials? Who is to say some of them aren’t secretly communists? Until each one submits to a lie-detector test, we must assume there are communists occupying our highest offices.”

Guilty until proven innocent? That's bleak. 

“I am calling for a complete and total shutdown of Muslims entering the United States until our country's representatives can figure out what the hell is going on.” 

It might feel like I'm picking on Trump, but I'm not. He just happened to be president when I wrote this chapter. If I had written it a few years earlier, it would be full of Obama quotes. But this quote is a great example of appealing to ignorance. Since we don't know who the terrorists are, let's assume everyone who is Muslim or foreign or seeking asylum is a terrorist and go from there. Like the example above, it proposes a guilty-until-proven-innocent approach.  

Strawman: Setting up and then knocking down a very weak-version of your opponent's argument.

Argument Against Anderson: “Senator Anderson wants to eliminate police departments and funnel that money into after-school art programs for illegal aliens.”

Anderson’s Original Quote: “The state police already has more armored vehicles than they can use. For the price of one of those trucks, we could fund every afterschool program across the state for a year.”

If you only read the first quote, you might agree that Senator Anderson is a threat and shouldn't be elected. But when you read what she actually said, you realize that she was misquoted and misrepresented. 

Hillary Clinton did this when giving a stump speech. Bernie Sanders had made a comment about the need for stricter laws that would force candidates to disclose where they got their campaign contributions. So Hillary said, “There is this attack that Sanders is putting forth that anybody who ever took donations or speaking fees from any interest group has been bought!" People cheered. But I doubt many were Googling it to find out what Bernie really said. 

As a parent and a school administrator, I have learned to wait to get both sides of the story before acting on someone's complaint. It's human nature to misrepresent events in our favor. We conveniently leave out important information or exaggerate innocuous details. This doesn't make us bad people. It's a survival strategy we learn at a young age. But another important survival strategy is to learn how not to react until you have verified information, checked the facts, and gotten the whole story. Don't be manipulated by someone else's strawman fallacies. 

False Dichotomy (aka False Binary or Either-Or Fallacy): Setting up an argument to look like there are only two choices (and ignoring all the other possibilities).

“If you’re not with us, you’re against us.”

George W. Bush said this in response to the French government declining to assist the US in invading Afghanistan after 9/11. The president's words upset the French people, and a lot of Americans too, because the reality was that there were other possibilities. The French were very much "with us," they just weren't in a position to invade another country. France couldn't be the "ride or die" buddy we needed in the moment, but the county was still our ally and on our side. For a couple of years after this, by the way, many businesses in the US replaced French fries with "freedom fries." I'm not sure how France ever recovered. 

“If St. George citizens want better public schools, they’ll need to pay higher property taxes. If they refuse to pay more taxes, then they’ll never have better schools.” 

There are other ways to improve schools beyond simply raising property taxes (grants, bonds, donations, training, redistricting, change in leadership, etc.). 

Issues are rarely black-and-white, this-or-that, cut-and-dry. Offering only two options creates a lot of problems and creates a difficult premise to defend. 

Equivocation: Sliding between different meanings of an important word or phrase.

“Washington Elementary needs to hire a paraprofessional to help students with dyslexia. Studies show that students with behavioral issues do better when there is a teacher's aid in the classroom.”

Writers and readers hate redundancy, so it's natural to use synonyms to keep our writing lively. If you find yourself using the word college ten times in a paragraph, you probably want to replace it a few times with words like university, higher education, institution, and school. Be careful, though, that you don't use a word that means something different--that's when equivocation occurs. In the example above, the student used behavioral issue in place of dyslexia, and dyslexia is not a behavioral issue (thus making the argument weak and easy to attack). 

Another way to avoid equivocation is to use specific terms. General terms make your argument easier to attack. If you write an argument about the need for the government to ban drugs, it will be too general and flimsy. Your reader will be confused. Which government do you mean--federal, state, or local? And what types of drugs are you talking about--over the counter, marijuana, opioids, opiates, schedule 1, meth, children's Tylenol? 

*Bonus* Godwin's Law of Nazi Analogies: Making Lame Comparisons to Hitler, Nazis, or the Holocaust to Win an Argument 

In the 90s, a lawyer named Mike Godwin noticed that if an online discussion or debate went on long enough, someone would resort to making ridiculous comparisons to Hitler, Nazis, and the Holocaust. Often, people will compare their opponent or someone they don't like to Hitler, or they compare people who disagree with them to Nazis, or---more abhorrently--they compare their situation or their own suffering to the Holocaust. 

These comparisons rely on multiple logical fallacies, such as false analogy, ad hominem, straw man, appeal to pity, slippery slope, and red herring. 

No matter which fallacy they use, they are in poor taste and should be avoided. 

Intentional and Unintentional Use of Fallacies

For the most part, you want to avoid using logical fallacies in your writing. The less fallacies you have, the stronger your argument. But there are times when you might want to purposely use a fallacy. Almost three-hundred years ago, Johnathan Swift, the Irish author of Gulliver's Travels, wrote an argument that was published in several newspapers called, "A Modest Proposal." In the essay, he took a sincere tone as he suggested that there was a simple solution to the famine and the economic problems of the day: poor people could sell their babies to nobility. He went on to explain how delicious a roasted infant could be and how eating children would be a win-win for everyone. Most people realized that he was exaggerating--that he was purposely using logical fallacies to make his point. A few people, however, thought he was sincere and were outraged by the letter. Now days, some people still feel equally outraged when they watch the cast of Saturday Night Live poke fun at the president, or when the author of "The Borrowitz Report" in The New Yorker suggests that we would all benefit from Trump getting a hand-enlargement procedure. Satire as a form of argument doesn't work for everyone, and that's because in order for it to be persuasive, you have to realize it's a joke. You have to recognize that logical fallacies are being used purposely and ironically. 

As I mentioned above, DirecTV understands the power of satire as an argument. They built an entire ad campaign on humorously engaging in the slippery-slope fallacy, suggesting that if you don't sign up for DirecTV, something terrible will happen to you (such as ending up in a roadside ditch): 

(If the embedded video doesn't work, try this link: https://youtu.be/kIv3m2gMgUU)

The marketing team for Direct TV knows they are using a logical fallacy, and they know that you, the viewer, knows it's a fallacy. They want you to know. They aren't trying to be subtle or manipulative. The power of the commercial is that you are in on the joke. You laugh. You get it. It's funny. 

Sometimes, though, marketers purposely engage in logical fallacies hoping that you don't notice. Recently, Microsoft launched an ad campaign for their Surface Pro, a tablet with a detachable keyboard. In a light, jaunty commercial, they compare the Surface Pro to a MacBook Air, humorously pointing out that the MacBook doesn't have a touch screen, that its keyboard doesn't detach, and so on. What they are hoping you don't notice is that they are committing the logical fallacy of weak analogy. If you compare the Surface Pro to the MacBook Air, then of course you're going to find a whole host of differences. But the wise viewer will recognize this fallacy and call foul, just as my thirteen-year-old son did when he saw the commercial. "The Surface Pro is like an iPad Pro," he said. "So why are they comparing it to a MacBook? They're not even the same thing." I was proud of his astuteness and a little embarrassed that I hadn't caught it myself. We weren't in on the joke like with the DirecTV commercial. They were trying to trick us--trying to sneak the logical fallacy by in the hopes we wouldn't notice. In short, they were trying to manipulate us. I don't know about you, but I would rather not be manipulated, which is why I do my best to notice logical fallacies. 

(If the embedded video doesn't work, try this link: https://youtu.be/7GuCJGRj33c)

In the following graphic, I illustrate how using or avoiding logical fallacies--and whether or not the reader is supposed to realize there are logical fallacies--can determine just what kind of argument you are making: a strong argument, a weak argument, a manipulative argument, or a satirical argument. To put it simply, if you want to make a strong argument, then do your best to avoid logical fallacies. If you want to make a weak argument, then riddle it with fallacies. If you want to make a manipulative argument, then purposely use fallacies, but try to hide them (you don't want the reader to realize what you're doing). And if you want to make a satirical argument (which I would argue is another type of strong argument), then purposely use logical fallacies, but do so in a way that your readers will realize that there are fallacies (let them in on the joke).