This book describes aspects of consciousness in ways that are often, but not consistently, clear and informative. His ideas are not revolutionary, but will clarify our understanding.

I didn’t find his tunnel metaphor very helpful.

I like his claim that “conscious information is exactly that information that must be made available for every single one of your cognitive capacities at the same time”. That may be an exaggeration, but it describes an important function of consciousness.

He makes surprisingly clear and convincing arguments that there are degrees of consciousness, so that some other species probably have some but not all of what we think of as human consciousness. He gives interesting examples of ways that humans can be partially conscious, e.g. people with Cotard’s Syndrome can deny their own existence.

His discussion of ethical implications of neuroscience points out some important issues to consider, but I’m unimpressed with his conclusion that we shouldn’t create conscious machines. He relies on something resembling the Precautionary Principle that says we should never risk causing suffering in an artificial entity. As far as I can tell, the same reasoning would imply that having children is unethical because they might suffer.

This book uses an understanding of the limits to human rationality to explain how it’s sometimes possible to make valuable behavioral changes, mostly in large institutions, with relatively little effort.

The book presents many anecdotes about people making valuable changes, often demonstrating unusually creative thought. The theories about why the changes worked are not very original, but are presented better than in most other books.

Some of the successes are sufficiently impressive that I wonder whether they cherry-picked too much and made it look too easy. One interesting example that is a partial exception to this pattern is a comparison of two hospitals that tried to implement the same change, with one succeeding and the other failing. Even with a good understanding of the book’s ideas, few people looking at the differences between the hospitals would notice the importance of whether small teams met for afternoon rounds at patients’ bedsides or in a lounge where other doctors overheard the discussions.

They aren’t very thoughtful about whether the goals are wise. This mostly doesn’t matter, although it is strange to read on page 55 about a company that succeeded by focusing on short-term benefits to the exclusion of long-term benefits, and then on page 83 to read about a plan to get businesses to adopt a longer term focus.

This broad and mediocre survey of psychology of people who stand out in history probably contains a fair number of good ideas, but it’s hard to separate them from the many ideas that are questionable guesses. He’s inconsistent about distinguishing his guesses from claims backed by good evidence.

One of the clearest examples is his assertion that childhood adversity builds character. He presents evidence that eminent figures were unusually likely to have had a parent die early, and describes this as the “most impressive proof” of his claim. He ignores the possibility those people come from families with a pattern of taking sufficiently unusual risks to explain that evidence.

In other places, he makes mistakes which seemed reasonable when the book was published, such as “Mendelian laws of inheritance are blind to whether an individual is first-born or later-born” (parental age has a measurable effect on mutation rates).

He avoids some of the worst mistakes that a psychology of history could make, such as trying to psychoanalyze individuals without having enough information about them.

He mentions some approaches to analyzing presidential addresses and corporate letters to stockholders, which have some potential to be used in predicting whether leaders have the appropriate personality for their jobs. I wonder what would happen if many voters/stockholders demanded that leaders pass tests of this nature (I’m assuming the tests can be scored objectively, but that may be shaky assumption). I’m confident that we’d get leaders with rhetoric that passes those tests. Would that simply mean the leaders change their rhetoric, or would it be hard enough to maintain a mismatch between rhetoric and thought patterns that we’d get leaders with better thought patterns?