And yet to say such things in public is to invite shock and ridicule. The educational romantics will pummel you with four objections: 1) When children are below average, we can raise their ability; 2) the schools are so bad that children at all levels of ability can learn much more than they are learning now; 3) the rising test scores of the past decade prove that major improvements are possible; and 4) there's no reason why the high educational achievement of children of the professional classes of ability cannot be achieved by all classes.

First, a bit of housekeeping. When talking about ability to succeed in the academic track, two of Gardner's abilities, linguistic and logical-mathematical - the two abilities that dominate IQ scores - are crucial. Rather than referring to them separately, from now on I will refer to the combination of the two as academic ability. This is not to say that those two are the only abilities relevant to success in school. Intra-personal ability in the form of self-discipline and perseverance is also important. But all the self-discipline and perseverance in the world won't help if enough underlying academic ability isn't there.

Think of the relationship of academic ability to academic success as you think of the relationship of height to success as a centre in a professional basketball team. Height isn't the most important factor - for people who are at least 6ft 10in (just over 2 metres) to begin with.

Now to the first issue: do we know how to raise academic ability through interventions? Since the most intensive experimental efforts to raise academic ability have been undertaken in the United States, and by now we have accumulated 40 years of evaluations of their success, I will use American data for the answer: the best we can do is nudge academic ability by a small increment, and even that much is difficult and uncertain.