Grant tackles the difficulties of trying to change in an interpersonal context the more firmly entrenched varieties of people’s beliefs, such as those underlined by prejudice or those governed by conspiratorial thinking. In chapter 6, he examines the longstanding animosity between Red Sox fans and Yankees fans in order to analyze the nature of rivalries and to test the effectiveness of different interventions at softening people’s prejudicial thinking.

Through a number of experiments and interviews, it was discovered that fans regularly prioritized their hatred for a rival team more than support for their own. At one point, when asked what it would take to consider rooting for the other team, some people replied maybe if the rival team was playing against terrorists. Rivalries are thus characterized by a strong desire to see the other person lose or even suffer. These rivalries tended to form even when the subject matter or reasons were trivial. All it required was a feeling of identification with one social group, and the practices and beliefs of the group were then passed down as a part of heritage or tradition.

In addition to this, the researchers found that beliefs progressed to extremes for various reasons. One reason is that because beliefs are a fundamental part of our worldview and how we process reality, challenges to it can feel disorienting. As such, people are often invested in aggressively defending and affirming their beliefs. Another reason is the phenomenon known as group polarization—when people with similar extreme beliefs deliberate in a group context, their interactions significantly augment their beliefs because they only really push each other in the same direction.

After testing several approaches of how to best counteract stereotypes, the researchers found that bringing someone to contemplate the arbitrariness of their views is the most effective. Grant suggests exercising someone’s counterfactual thinking: “How would things be different if you were born into a different demographic?” The chapter ends with the story of Darryl Davis, a Black American musician who is well-known for his record of leading white supremacists to reconsider their worldviews through conversation. He seems to change their minds by evoking and entertaining their curiosity and imagination.