I just finished How We Decide by Johan Lehrer.

How We Decide is one in a raft of pop sci books that use behavioural research to discuss how human behaviour departs from the theoretical rational "economic man" model.

A lot of the research discussed is actually old and I've been exposed to it in various other books, but the new twist is the Malcolm Gladwell-esque narrative pop sci spin put on it.  Not much new to see, but presented in a palatable format.

There are a number of places where Lehrer over-extends the meaning of these results.  For a start, he uses a naive view of reason, mentioning Plato's views of reason opposing emotions, and then takes that as the standard in all of western civilization.  But, as he points out himself, Plato's pupil Aristotle had a more nuanced view that held that the true reasonable man knows that both reason and emotion have their places and the struggle is to find where they should be applied.

An example of this naive view of reason can be seen in his discussion of the ultimatum game, where one party is allowed divides a reward and the other party can choose to accept the division or both parties get nothing.  Naive theories of reason like those used in basic game theory lead to the conclusion that the offerer should make a very minimal offer and that the receiver should accept it, because it is still better than nothing.  In contrast, in the real world most offerers make a much closer to even distribution and most receivers will reject the offer if it is not closer to even.  This is taken as evidence of irrationality, but it is only irrational in that it shows most people can not isolate their thinking into such an artificial context on demand.  In real world behaviour, demanding a more even split will result in better payoffs for the receiver over time, and making more even splits will result in better payoffs for the offerer over time, since they know that receivers will demand higher payoffs.  At this higher, more realistic level, the outcome is completely rational.

On the other hand, he also discusses framing effects, where the identical problem elicits a different response depending on how it is presented, clearly a sign of inconsistent and irrational behaviour.

Another weak part of the book is the section on morality.  He connects morality and emotions in a strong way, postulating that morality is based on emotional reactions to and sympathy with other people.  He lists  psychopaths as examples, since they lack emotional affect and behave in an immoral fashion.  But he doesn't give any explanation for the observed variation in morality across cultures and across time, or for the lack of serious immoral behaviour among autistics, another group that lacks emotional affect and sympathy.

There are better books on the same subject.  This one is OK if it is your first introduction to the subject.