The human brain is the most complex machine known to man; understanding its workings is a task that we have barely started. In this book, Steven Pinker - one of my favourite scientists, and one of the most brilliant around - brings his formidable analytic strengths to bear on a host of issues in cognitive science, and deals with them all in thought-provoking (and often droll) ways.

Something that appeals to me about the book is his willingness to admit where explanations are currently beyond the ambit of cognitive science. I have in mind consciousness, which has been the subject of many abortive attempts at explanation; although some of the mechanisms which give rise to consciousness have been explained, in my opinion writers such as Daniel Dennett have been mistaken in claiming that we now understand why consciousness should arise from these mechanisms.

One of the few places where I disagree with Pinker is where he brackets free will with consciousness as something which may not be understood in the foreseeable future. As I argue elsewhere on the site, I actually don't think that free will exists. In a nutshell, there is nothing outside the interaction between genes and environment; although we are obviously capable of many choices, the ultimate determinant of what sort of person we will be is the interaction between these forces, neither of which is a matter of choice.

He is extremely illuminating when it comes to many of the strange activities of modern societies:

"Our minds are adapted to the small foraging bands in which our [species] spent ninety-nine percent of its existence, not to the topsy-turvy contingencies we have created since the agricultural and industrial revolutions. Before there was photography, it was adaptive to receive visual images of attractive members of the opposite sex, because those images arose only from light reflecting off fertile bodies. Before opiates came in syringes, they were synthesized in the brain as natural analgesics. Before there were movies, it was adaptive to witness people's emotional struggles, because the only struggles you could witness were among people you had to psych out every day. Before there was contraception, children were unpostponable, and status and wealth could be converted into more children and healthier ones. Before there was a sugar bowl, salt shaker, and butter dish on every table, and when lean years were never far away, one could never get too much sweet, salty, and fatty food. People do not divine what is adaptive for them or their genes; their genes give them thoughts and feelings that were adaptive in the environment in which the genes were selected."

There is much controversy about which of our thoughts and feelings have been influenced by our genes; the respected science commentator John Maddox opines that sociobiology (the application of evolutionary theory to the understanding of human psychology and society) has come too early, because we don't understand enough about the brain. He goes on: "the speculations of evolutionary psychology are so manifestly lacking an empirical foundation that they trivialise the reputation of science". It is certainly true that we are only beginning to sketch out the relationship between brain and behaviour; it is also obvious that there are many silly hypotheses about why particular human traits arose. But I think Maddox misses the fact that we can carry out empirical research (i.e. research based on lots of carefully-controlled observations) on the constants of the human mind - for example, by examining identical twins separated at birth, comparing very different societies, using control groups, etc. And empirical research is the bedrock of science.

Pinker recounts some remarkable findings which strongly challenge many views on character formation:

"Much of the variation in personality - about fifty percent - has genetic causes. Identical twins separated at birth are alike; biological siblings raised together are more alike than adopted siblings. That means that the other fifty percent must come from the parents and the home, right? Wrong! Being brought up in one home versus another accounts, at most, for five percent of the differences among people in personality. Identical twins separated at birth are not only similar; they are virtually as similar as identical twins raised together."

He deals with a vast range of subject matter, and as such is likely to make some mistakes; however, the scope, empirical grounding , and acuity of the book are hugely impressive. Of all the scientists whose work I have understood, his mind strikes me as the most brilliantly penetrating.

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