Book review: What is intelligence?

What is Intelligence?  Beyond the Flynn Effect
by James Flynn (2007)

Two paradoxes:

  • Studies of separated twins prove that genes are much more important than environment for IQ.  The fact that the population’s IQ is increasing at a rate of 0.3 points per year proves that environment must be more important than genes.  Which is it?
  • If the “Flynn effect” is taken seriously, our grandparents are retarded and our grandchildren are geniuses (both compared to us).  Why don’t we notice this?

What does The Man Himself have to say?  First, that environment can amplify small genetic differences.  Those with higher aptitude tend to be put in (and to enjoy and hence seek out) more stimulating and challenging environments.  Thus, environmental effects may be very potent while genes still predict IQ within a single generation / social context.  Second, we prioritize abstract over concrete thought much more now than in the past, and IQ and other psychometric tests tend to take abstract thought as normative.  Third, IQ gains are not even across all subtests; nor do the gains match the g-loading of each subtest as determined at one moment in time.  Our grandparents had roughly as good vocabulary as us, and hence comparable ability to appreciate literature.  On the other hand, they may not be as good at solving meaningless abstract puzzles, such as the Raven’s Progressive Matrices.

On the other hand, they might be.  Although I don’t recall seeing it suggested in the book, if socially-evolving environmental forces are as potent as Professor Flynn believes, perhaps our grandparents’ IQs have been drifting upward with the population as a whole.  Flynn also does not consider that there might be some downside to over-reliance on abstract thought, which would also complicate the supposed superiority of our time.

Professor Flynn is fond of sports analogies.  One can become a better runner by training, although we each have different natural aptitude, and most of us don’t have the potential to be Olympic athletes.  So he believes it is with intelligence as well.  I have suggested before that low intelligence people like me must learn to be careful how we allocate our cognitive effort, but perhaps avoiding too many challenges is one of the things that is keeping us dumb.


5 Responses

  1. Of course, nature and nurture can be functions of each other.

    Take the condition that used to be called cretinism and was believed to be genetic. It was characterised by severe learning difficulties.

    It is now called Phenylketonuria, since research into the aetiology of the condition has shown that the associated brain damage is caused by phenylalanine in the diet; an environmental factor. But the inability to metabolise phenylalanine is a genetic condition.

  2. Recent genetic studies suggest that western countries are losing about 1 IQ point per generation:

  3. Bruce Charlton has co-written a very plausible e-book that, to me, contradicts and counters Flynn’s narrative of increasing intelligence.

    Charlton et al take the example of the decline of instances of genius in the last two centuries, taking examples such as music, literature and science. They explain it as being due to reduced childhood mortality, enabling the survival of more human beings inflicted with degradative mutation (recent discoveries indicate that, contrary to the neo-Darwinists, these are the only kind) which, by the nature of things are most likely to affect, and inflict the most severe damage to, the central nervous system.

  4. When an instrument drifts out of calibration, this proves that the underlying phenomena it is designed to measure are part of a pseudoscience. Everyone know that.

  5. […] fact, there was a precedent for this from back in my day. In What is Intelligence, James Flynn cites increased complexity of television shows as evidence of increasing intelligence […]

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