How to Think by Alan Jacobs is a work of nonfiction arguing for the importance of critical thinking in our increasingly polarized society. Jacobs references many important thinkers of the past, contemporary pundits and journalists, and public and political figures.

René Descartes

René Descartes (31 March 1596 – 11 February 1650) was a French philosopher and mathematician. In philosophy, he is known for his famous statement "cogito ergo sum" (I think therefore I am) and his notion of what has come to be called "Cartesian meditation," a process by which one empties one's mind of preconceptions simply reflected on what one can know with certainty by reflecting on one's own cognitive process. Jacobs objects to the solitary model of Cartesian meditation and emphasizes the importance of collective wisdom in thinking.

Daniel Kahneman

Daniel Kahneman (born March 5, 1934) is an Israeli American psychologist and economist known for his work on behavioral economics and studies of how people make decisions. He is especially known for "prospect theory," which shows that people react asymmetrically to the future possible prospects of gains and losses, with the risk of loss having a greater psychological impact than desire for gain. In other words, people will often act in a way to avoid small losses even at the cost of missing out on potentially larger gains.

Jonathan Haidt

Jonathan Haidt (born October 19, 1963) is a cultural psychologist whose work is cited by Jacobs. Haidt identifies as an obstacle to good thinking and a source of polarization in society the way people tend to make judgments based on intuition and then rationalize those intuitions rather than thinking rationally in many circumstances.

David Dunning and Justin Kruger

David Dunning and Justin Kruger are contemporary psychologists known for having jointly written about what is called the "Dunning–Kruger effect." This is a form of cognitive bias in which people make mistakes in estimating their own abilities. Interestingly, the most skilled people at a certain task slightly underestimate their own relative skill compared to others, whereas the least skilled and least knowledgeable tend to dramatically overestimate their own abilities. Jacobs talks about the "Dunning–Kruger effect" as an obstacle to thinking well.