By already knowing who they are and their general views on the subject. Kamin will say environment, Pinker will say genes, Gould will say environment, and Sesardic, I have learned, will say genes. And if in doubt, the publisher's blurb will tell me all I need to know if I'm not going to do my own extensive research.

In fact, the situation is even worse: to have a real view of my own, not only would I have to acquire expertise sufficient to write my own book, I would have to achieve substantially greater expertise than all of the people whose conclusions I ended up disagreeing with, in order to have reasonable grounds to think that I was right and they were wrong.

Who has the time?