Mind & Body

Presenting Too Much Evidence Could Make You Lose an Argument

Let's say you're debating something on Facebook or Reddit. Most of the replies in the comments are a sentence or two long and it's easy to quickly see what everyone has to say. Then, one person posts a wall of text. We're talking 10-15 bullet points or more, with links to everything from scientific studies to national news stories. Pretty persuasive, right? Well, science says you're actually more likely to reject that argument, thanks to the overkill backfire effect.

Overkill? More Like Killtastrophe

We've already talked about the backfire effect, which says that when you hear contradictory evidence, your beliefs actually get stronger. It's like the flipside of confirmation bias, which makes you seek out information that agrees with your preexisting beliefs. These are just a couple of many psychological quirks in your brain that can impact how you receive and process information, whether you're an average person or a scientist performing an experiment.

The overkill backfire effect is a little different than the plain-old vanilla backfire effect. In both cases, you're being presented with information that contradicts your views or an argument that you're already predisposed to disagree with. But in this case, you're rejecting the argument for a specific cognitive reason: It's harder to process a more complicated argument. Even when the argument is science-based, like trying to convince someone that vaccines are safe, science says that it's crucial to present just a few facts when making your case, not dozens.

Multiple studies have demonstrated that people are more confident in their judgments when information is easy to recall, and it's easier to remember information that was easy to process in the first place. How easy? One study showed that when reading a printed statement, people were more likely to accept the statement as true when the researchers increased the color contrast of the font it was printed on, thus making it easier to read. Yes, that easy.


Writers and philosophers get it. In the 14th century, Franciscan Friar William of Ockham wrote that the simplest explanation is usually the right one — a concept now known as Occam's Razor. A few hundred years later, Shakespeare famously wrote in Hamlet that "brevity is the soul of wit." And whether he came up with it or he simply made it popular, it's a policy that's been adopted by writers, politicians, and speakers for centuries. And that's just the tip of the iceberg: Adages like "less is more," "short and sweet," and "keep it simple" aren't hard to find.

There are a lot of benefits to keeping your case simple. Obviously, you'll save time coming up with a sentence or two to defend your position rather than feeling like you have to research and cite a dozen sources to make your case. You'll also make your argument stronger because a concise case means fewer opportunities for someone to hit you with an argumentum ad logicam, or argument from fallacy. That's a logical fallacy someone can use to argue that your entire point has no value because it contains one mistake in its laundry list of facts.

At the end of the day, though, the best part of presenting a simple case is that you can always add more evidence later. By presenting a simple idea, you're more likely to get someone's attention in the first place, which can lead to further dialogue. And isn't that the whole point of arguing?

Just remember that you, too, are likely to be a victim of your own brain and fall prey to the overkill backfire effect. So when someone goes TMI on you, throw them a bone and ask them to simplify the point they're trying to make. It'll save you some time if they're willing to rewrite their argument, and you might even learn something in the process.

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For more persuasion tips and tricks, check out "Thank You for Arguing, Third Edition: What Aristotle, Lincoln, and Homer Simpson Can Teach Us About the Art of Persuasion" by Jay Heinrichs. The audiobook is free with an Audible trial. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Cody Gough June 15, 2018

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