Bregman describes how in 1954, a psychologist named Leon Festinger investigated a Chicago doomsday cult that predicted that they would be rescued by flying saucers late that year while the rest of the world be destroyed. When the end did not come, the believers devised rationalizations that reinforced their preexisting beliefs rather than confronting an obvious, if unpleasant, truth. Core beliefs are powerful, and when something challenges them, people become highly resistant to persuasion—and education can make them better skilled at defending those opinions rather than questioning them in the light of new evidence. Bregman confesses to treating information contrary to own convictions as an adversary to be bested rather than a chance to revise his beliefs. This raises the question of how ideas can change the world; they obviously have, since ideas have changed the world in countless and extraordinary ways over time, yet worldviews at any given time resist even minor challenges. Group pressure can be highly effective in maintaining beliefs, even patently false ones, but loud dissent can also encourage people to trust their own perceptions. Massive shocks should make people more amenable to changing their minds, but after the financial crisis of 2008, all attempts at serious reform to Wall Street failed, and