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This article is an excerpt from the Shortform book guide to "Rationality" by Steven Pinker. Shortform has the world's best summaries and analyses of books you should be reading.

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Which do you value more—the truth or fitting in? Do you allow your group’s beliefs to trump your better judgment?

Most people agree on the importance of rational thinking and behavior. Still, irrationality is rampant. Steven Pinker explores why people hold irrational beliefs such as paranormal phenomena or conspiracy theories in his book Rationality. He identifies myside bias as one of the culprits.

Read more to learn about this all-too-common tendency that impacts individuals and society as a whole.

Myside Bias

Pinker notes that social media has allowed people to express their irrational beliefs loudly, which makes it seem that irrational thought is a growing and recent phenomenon. But, he argues that people have believed these types of ideas for millennia. Pinker discusses one of the causes of such human irrationality in the modern world: myside bias.

(Shortform note: Myside bias is a recent example of a phenomenon dating back to ancient times. For thousands of years, for example, people have believed in shadowy groups controlling the world, right back to the ancient Egyptians complaining of Grecian priests who held secret knowledge and the 18th-century belief in the Order of the Illuminati. Still, despite scientific studies showing that conspiracy beliefs have not become more common in recent years, many people feel, as Pinker points out, that they have increased in frequency—an example, ironically, of more irrational thinking, in this case, based on the availability heuristic: What people notice today, they assume is more likely.)

Myside bias is the tendency to irrationally favor information or conclusions that support your group. It’s largely driven by our desire to be part of a collective, and, in this way, is rational. If your goal is to be respected and valued by your peers, it makes sense to express opinions and even see things in a way that earns this respect. But, the result is that you’ll likely think and behave irrationally, overlooking the logical flaws of arguments that support your own side while fixating on the flaws of the other side.

Pinker writes that virtually everyone is susceptible to myside bias no matter their political affiliation, race, class, gender, education level, or awareness of cognitive biases and fallacies, and that myside bias is driving the heated political climate of recent years. He points to studies that show liberals and conservatives will accept or refute a conclusion or scientific evidence based on whether or not it supports their predetermined notions (not based on whether or not it’s well-argued or supported). Additionally, if an invalid logical statement supports a liberal idea, a conservative will be more likely to spot the fallacy, and vice versa.

(Shortform note: Though it’s important to be aware of your myside bias and to try to minimize it to avoid irrational thinking, scientists suggest that tribal bias is human nature and is thus impossible to eradicate entirely. Humans are tribal because we evolved as members of small groups in intense competition with each other—to survive, group loyalty was a must. Because this group dynamic has been so important to human survival, we’ve evolved to favor people who support our group’s thinking and behaviors, and thus people who align with a group’s values often have a higher social status within that group. This underpins the instinct to—sometimes blindly—support or parrot a group’s thinking.)

Exercise: Examine Your Myside Bias

Consider how myside bias might be affecting your beliefs or your interactions with others.

  1. How closely do you consider your political beliefs to align with the people closest to you? Do you associate with people at work or in your personal life who hold significantly different views than you?
  2. Think of a belief you hold that people close to you—friends, family, or coworkers—might not. Would you be hesitant to share this belief? Why or why not?
  3. Think of a time you’ve had a conversation with someone who has different beliefs than you. How might you have dismissed some of their ideas before properly considering them? Are there any aspects of their ideas you might accept if you thought through them more neutrally?
  4. Consider how you might converse with someone you disagree with the next time the subject of your disagreement comes up. How might you respond to some of their arguments, keeping in mind the goal to not irrationally dismiss facts or thoughts that don’t fit your worldview?
How Myside Bias Fuels Irrationality & an “Us vs. Them” Mentality

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Like what you just read? Read the rest of the world's best book summary and analysis of Steven Pinker's "Rationality" at Shortform.

Here's what you'll find in our full Rationality summary:

  • Why rationality and reason are essential for improving our world and society
  • How you can be more rational and make better decisions
  • How to avoid the logical fallacies people often fall victim to

Elizabeth Whitworth

Elizabeth has a lifelong love of books. She devours nonfiction, especially in the areas of history, theology, and philosophy. A switch to audiobooks has kindled her enjoyment of well-narrated fiction, particularly Victorian and early 20th-century works. She appreciates idea-driven books—and a classic murder mystery now and then. Elizabeth has a blog and is writing a book about the beginning and the end of suffering.

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