I'm just checking in here to say that this is a very rich and rewarding book - it's full of fascinating discussions, and I've gotta marvel at the enormous amount of material that Steven Pinker has pulled together to advance his (complicated) thesis.
I've just been reading his take on the Flynn Effect: the increasingly high IQs of each cohort over the years, since intelligence tests were invented. Or, rather, the increasing difficulty in performing well on IQ tests: IQ testing is continually updated to keep the average IQ at 100. An "average" person today, measured by her score in an intelligence test, would obtain a score markedly above 100 if sent back in a time machine to be tested, say, 70 years ago. An average person from 70 years ago (whisked forward in the same time machine) would achieve a very low score if measured by a modern intelligence test.
Why might that be so? Average people in the World War II era were not incompetent at managing their daily lives. They were not lacking in the ability to express themselves and get along. They did not falter when confronted by simple arithmetic. Someone from that era who might score, say, 80 on a modern intelligence test would probably seem very different from a contemporary person who gets that score on a modern intelligence test - someone who probably struggles in a lot of ways.
Pinker doesn't put it like this, but it may look as if intelligence tests measure the relative "intelligence" of people within a cohort - i.e. they compare something, or a cluster of "somethings", among these people. However, so it may appear, they only work to compare people of more or less the same generation. You can't straightforwardly compare the results of people from different generations on the same test. (This may also apply to people from different geographic localities, and perhaps different cultures, sub-cultures, etc.)
Is that right? Is it the whole story? Or is there some sense in which people really are getting smarter? If so, what are the implications?
I won't go into Pinker's answers today, except to say that his take on it is eye-opening if he's correct and that, to me, a lay person in this area, it seems plausible. Perhaps he's wrong, and this may come out as reviews of the book accumulate (some will be written by people with expertise in the area), but perhaps not.
His discussion of the issue, as he lays out the conundrum, zeroes in on an explanation ... and draws some conclusions with dramatic implications if they are correct ... is not merely adroit, although it certainly is that. It is positively exciting.
Again, this is how a non-fiction book should be written if it aims to entertain and involve - as well as instruct - a broad educated audience. Pinker provides a model for us all, not necessarily one we can match, or one that will suit every topic without modification, but definitely one we can aspire to. I'm loving it.