Something has been going wrong on many college campuses in the last few years. Speakers are shouted down. Students and professors say they are walking on eggshells and are afraid to speak honestly. Rates of anxiety, depression, and suicide are rising—on campus as well as nationally. How did this happen?

First Amendment expert Greg Lukianoff and social psychologist Jonathan Haidt show how the new problems on campus have their origins in three terrible ideas that have become increasingly woven into American childhood and education: What doesn’t kill you makes you weaker; always trust your feelings; and life is a battle between good people and evil people.