376. The Conjunction Fallacy

0:00Have you ever wondered how two people could look at the exact same thing and come away with two very different opinions on what it means? Or have you been baffled how someone could believe something that, to you, is obviously untrue? This kind of thing happens all the time. But how can you be sure you're the one seeing things accurately? Hi, I'm Kathy, a homeschool mom, passionate about teaching critical thinking to the next generation, so they're propaganda proof and impossible to fool with bad arguments. And I like to have fun doing it. Welcome to the Filter Through a Brain Cell Podcast. Hey, what is up thinkers? Okay, let's start off today's episode by reviewing a bias that we covered earlier in season two called the cheerleader effect. Okay, do you want to hit pause and see if you can remember what the cheerleader effect is? So the cheerleader effect is a cognitive bias where individual people seem to appear to be more attractive when they are seen in a group of people than maybe they appear to be when they are viewed alone.

1:00And this phenomenon occurs because our brains tend to average the attractiveness of multiple faces in a group that kind of smooths out unique features and enhances the overall appeal of each individual person. It's like when you see a group of people, everybody just seems to look like they look a little bit better than they might in real life. So if you want to review or hear more about this bias, you can go back and check out episode 297. Okay, so let's dive into today's new bias as we are slowly actually kind of quickly now checking off the biases that we're going to be covering in this season. But today's is called the conjunction fallacy bias. I know I'm calling it two names. Does that sound confusing? Well, this one is actually both a logical fallacy and a cognitive bias because it's an error in thinking and it's just a shortcut that our brain does. So let's define the word conjunction. A conjunction is when two or more things are joined together and therefore must all be true at the same time.

2:00If you remember from your English, one of the, you know, conjunctions are words that join things together like and or but or if, right? So the conjunction fallacy bias is a mistake in reasoning that happens because our brains are biased toward stories that seem like they fit together. So the conjunction fallacy occurs when we believe that a combination of events is statistically more likely than just one of those events happening by itself, even though that's mathematically impossible. It's mathematically way more possible for just one thing to be true than for two things to both be true at the same time. So let me explain kind of what this means. So here's a few simple examples of what this can sound like. So imagine your friend loves animals. They volunteer to shelter and dream of becoming a veterinarian, which seems more likely that she'll become a veterinarian or that she'll become a veterinarian and own three rescue dogs.

3:01Well, most people will pick the second option because it sounds like a better story. But it can't be more likely than simply becoming a veterinarian. So statistically, it's so much easier to only get one thing to be true than to get two things to be true. Okay, here's another example. Or maybe let's say your brother loves video games and computers. So which is more likely that he'll work with computers someday or that he'll work with computers and become a famous video game designer. So again, the more detailed story feels to us like it's more believable, even though statistically, it's actually less likely to have two things both end up being true. Or let's imagine that someone says Sarah loves baking and helping people. Okay, which is more likely that Sarah will own a bakery or that she'll own a bakery and donate bread to homeless shelters every Saturday. Well, the second description feels more complete. However, when you add extra conditions, it always makes something less likely, not more

4:05likely. And if this feels like your brain is saying, what? How is this possible? Well, that's because this is what our brains do. So why? Well, our brains commit this bias because we love stories that seem to make sense. And when extra details fit the picture and kind of color in the picture a little more clearly that we've already formed in our minds, the story starts to feel more believable. And we mistake that feeling for statistical probability. So in other words, we are judging how realistic the story sounds instead of actually basing it on logic. And there was a famous demonstration of this that came from a study that the psychologist did in this time. It was the 1980s, but it was called the Linda problem. Okay, so it's all about Linda. In this study, participants read about a woman named Linda who is described as being deeply concerned about social justice and discrimination. And then they were asked which was more likely that Linda was a bank teller or that she was

5:06a bank teller and also active in the feminist movement. Well, most people chose the second option because it matched Linda's description better, even though the first option had to be more statistically likely. And again, here's why it's statistically more likely that Linda was just one thing, it's a bank teller because every time you add an end, you're adding another condition that also has to be true, making the combined event less likely than either event alone. So this study actually became one of the most famous demonstrations of how our intuitions about probability can kind of mislead us to make us think about things wrong. So the conjunction fallacy often appears in weather forecasting, like let's say for instance, after Hurricane is predicted to make landfall, people know it's coming, okay, the news has been talked about this hurricane. Well, people will frequently judge a forecast like the hurricane will make landfall as less likely than the more detailed prediction that sounds like the hurricane will make landfall

6:08in Florida. It's going to knock out power for more than 1 million homes and cause severe flooding in these rivers. Okay, the second forecast feels more believable to our brains because it's vivid and it tells a complete story. But statistically, it has to be less likely because every additional end adds another event that must also happen. And meteorologists often discuss probabilities for individual events separately for this very reason. And then they'll add specific conditions that might make a forecast sound more realistic, but it also makes the entire prediction less probable. Isn't that interesting? I know when we talk about statistics, it can get a little bit confusing, but hopefully you got the idea of what this bias is. So what about you? Have you ever found your brain experiencing the conjunction fallacy bias? And if so, when? And if you do, the question to ask yourself is this, what evidence supports each part of this claim?

7:08Let's say it again, what evidence supports each part of this claim because you have to look at each part of the claim separately. All right, y'all, that's it for today. For, biases happen automatically and will affect your ability to discern the truth. You can slow down your thinking by asking, what am I not seeing and how could my view be incomplete?