If I had to winnow the book to only one chapter, it would be the fifth, on the market for irrationality. Caplan’s claim in this chapter - if I read and remember correctly - is that the demand for irrationality increases as the price of irrational behavior (e.g. the consequences) decreases. So in the situation which Taleb proposed in The Black Swan, in which an ancestor crosses paths with a lion (or lets say a similar but less speedy predator), the rational choice is to flee (Taleb uses this situation to illustrate the cost of thinking). The cost of choosing irrationally and trying to pet the predator would be death or severe maiming. Now if you are located somewhere inaccessible from the lion, the cost of behaving irrationally, perhaps dancing and telling knock knock jokes to the cat, would be close to zero.