How you can avoid committing the "conjunction fallacy"
Here is a logic puzzle created by psychologists Daniel Kahneman and Amos Tversky.
"Linda is single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with the issue of discrimination and social justice, and also participated in demonstrations. Which of the following is more probable: Linda is a bank teller or Linda is a bank teller AND is active in the feminist movement?"
In studies, when asked this question, more than 80 percent of people chose number two. Most people said it was more probably that Linda is a bank teller AND active in the feminist movement, but that's wrong. Can you tell why?
This thinking mistake is an example of the subject of this episode - the conjunction fallacy. Listen as three experts in logic and reasoning explain why people get this question wrong, why it is wrong, and how you can avoid committing the conjunction fallacy in other situations.
This episode of the You Are Not So Smart Podcast is the ninth in a full season of episodes exploring logical fallacies. The first episode is here.
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Bob Blaskiewicz is an assistant professor who teaches, among other subjects, critical thinking at Stockton University. He also writes about logic and reasoning at skepticalhumanities.com, and is a regular guest on the YouTube show The Virtual Skeptics.
Julie Galef is the president and co-founder of the Center for Applied Rationality, a non-profit devoted to training people to be better at reasoning and decision-making. She is also the host of the Rationally Speaking Podcast and writes for publications like Slate, Science, Scientific American, and Popular Science. This is her website.
Vanessa Hill is an Australian science writer and stop-motion animator who hosts BrainCraft, a PBS series exploring psychology, neuroscience and human behavior. She previously worked for Australia's national science agency, as a science reporter for ScienceAlert, and has appeared in TIME,The Huffington Post,Scientific American, and Brain Pickings. Her Twitter page is here.
In every episode, after I read a bit of self delusion news, I taste a cookie baked from a recipe sent in by a listener/reader. That listener/reader wins a signed copy of my new book, "You Are Now Less Dumb," and I post the recipe on the YANSS Pinterest page. This episode's winner is Justin Near who sent in a recipe for Monster Cookies. Send your own recipes to david {at} youarenotsosmart.com.
Links and Sources
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Center for Applied Rationality
Extensional versus intuitive reasoning: The conjunction fallacy in probability judgment.
Looking at "Linda": Is the Conjunction Fallacy Really a Fallacy?
The Conjunction Fallacy at Bias123