Five ways to identify when arguments take an illogical turn

Have you ever been in a conversation with someone, reading a news story, or watching a sitcom in which someone said something that just didn’t make any sense—but you couldn’t really put your finger on why?

Normal, healthy communication is built on a structure of internal logic. Much of this structure is innate—something we learn and follow subconsciously. Built from a lifetime of reading good books and thinking critically about what we hear and say, our ability to follow a logical argument is crucial for understanding debates, news stories, and even conversations with our friends.

However, it’s easy to get lost in illogical stories and confusing rhetoric, and it’s important to learn how to sift through arguments and know which hold water and which don’t. Logic reduces bias—and where logic is abandoned, impartiality may also be left by the wayside. It’s likely obvious that campaign season—and the social media debates it generates—make now as good a time as ever to learn to recognize errors in logic.

Let’s look at five of the most common (and most sneaky!) ways in which arguments can take an illogical turn. A twist, turn, or manipulation of logic is often referred to as a fallacy, or a “failure in reasoning which renders an argument invalid.” Recognizing some common fallacies can help us figure out what to believe and how to respond to all the stories we encounter every day.

01. The red herring argument

This fallacy takes it name from literature. In a classic whodunit, for example, before the ultimate reveal of the guilty party, there will usually be lots of fake or misleading clues thrown into the story so that the reader can be led down a false trail—and so it’s not obvious how the story will end from the beginning. This fallacy can take many forms out in the wild, but one of its subspecies is referred to as ignoratio elenchi, or, more simply, missing the point. In order to avoid one argument, someone diverts the conversation into left field, and the original idea is abandoned. Here’s the idea:

“These apples are delicious. Apples are a good source of vitamin C, too, right?”

“Bananas have more potassium.”

How to recognize: If people are asking lots of confusing or vague follow-up questions instead of providing answers, or they redirect the conversation in a way that doesn’t answer the original point, that may be a red herring.

02. Argument from omniscience or authority

This one’s got an easy red flag to watch for: when someone in a hot seat or difficult position starts throwing around claims that “everyone knows that ...” (implying that whatever his or her opponent is arguing is silly, because obviously), it’s an argument from omniscience. It’s effective because no one wants to feel like they’re not in the know; and the “everyone knows that” statement psychologically slides into our brains, taps on our pride, and forces us to reconsider what we think we know. It takes courage to counter such a statement—so, often, this fallacy is more effective than it should be. Here’s a simple example:

“Apples are also really high in fiber.”

“That’s silly. Everyone knows that there are better ways to get your fiber.”

How to recognize: Whenever anyone states a very general fact for which a citation is definitely needed but not provided, that’s a clue that they may be arguing from omniscience.

03. Circular reasoning/circular definition

Imagine you’re holding a dictionary. Flip it open because—say—you want the Merriam-Webster definition for “circular definition.” When you find the entry, though, and you squint at the fine print, all that the dictionary has seen fit to say is that a “circular definition” is “a definition that is circular.” Not the most helpful, right? This is an example of a circular definition. Circular reasoning is very similar: it asks us to accept as a premise for an argument … what the argument itself is trying to prove. For example:

“It’s healthy to eat a lot of colorful fruits and vegetables for dinner.”

“Why do their colors matter?”

“Oh—well, because if you’re healthy, you’re probably eating a variety of colorful fruits and vegetables for dinner.”

How to recognize: Circular reasoning by definition doesn’t really go anywhere. If an argument is just saying the same thing over and over again, it’s probably stuck in a logical spiral. Circular reasoning is most effective when the argument in question is being made to people who already believe the argument—they just want to hear it restated in a new light.

04. Ad hominem

This is hands-down the most common logical fallacy that is seen at events like political debates. The Latin name for the fallacy means literally “toward the man,” and, aptly so: the ad hominem argument seeks merely to shoot the messenger. Instead of answering the argument posed, when using this fallacy, the speaker will try only to discredit his opponent so that whatever is said afterward is much less believable. It isn’t a very polite or chivalrous tactic, but it works as a combination red-herring and authority-argument approach:

“The vendor at the farmers market told me that tomatoes are best if you don’t refrigerate them, because the cold does something to its cellular structure.”

“That's nonsense. He can’t even grow a halfway decent tomato.”

How to recognize: If an argument veers quickly from facts to insults, it’s likely going into ad hominem territory. It’s also easy to do this if there is some acknowledged bias against the target of the argument. Always remember that who a person is and what he is saying are two different things.

05. Straw man argument

The straw man argument is another combination fallacy, basing itself on the red herring approach mixed with a little of the ad hominem attack. This fallacy concerns itself with answering an argument from the opposing side that was never posed in the first place. Often this takes the form of answering a position that is more extreme than the one held. For example:

“At any rate, I’d rather have an apple pie than a tomato pie, wouldn’t you?”

“All you eat are apples! You do know that they’re not an adequate source of protein, right? You want us all to be sick from protein deficiencies?”

How to recognize: This one is especially insidious because the second “answering” statement often takes the form of something that no one would ever disagree with. Consider the above scenario, for example: no one on the planet thinks that we should eat an all-apple diet, and most people agree that protein is very important in a balanced diet. But by the time that the second argument has landed, it’s very easy for an audience or a reader to forget what the original argument was in the first place. The best remedy for this one is simply a good sense of focus. Also, if you notice that loads of accusations have been tossed into an argument, watch out: there’s a good chance that a battalion of straw men has been called in for an opponent to shoot down one at a time, distracting us all from the original point.

If we’re well-equipped with the tools of logic, we can become better communicators—both in choosing what to say and in interpreting what others say to us. And in a time when genuine, respectful dialogue on controversial topics can be hard to find, we show respect for ourselves, our argument, and our audience when we take a moment to make sure that what we’re saying makes sense.