Charlton is Right …¶
… on this question, at least. The sole real puzzle is the precise quantity of dysgenic deterioration that has taken place in Western societies over the last 150 years, or more. Charlton estimates a one SD decline over this period in the UK, which seems entirely credible. Due to the small sample size, his argument from mathematical excellence has an inevitable anecdotal quality, but it would be hard to contest its general direction.
A fascinating paper by Michael A. Woodley (via @intelligenceres) is able to be more comprehensively persuasive. Its second table describes the innovation rate per capita across a sample of European countries falling by almost three-quarters over the period 1845-2005, and roughly halving from 1945-2005. (Great Stagnation anyone?)
It shouldn’t need adding that it’s impossible to read this often enough (it’s always there in my ‘Resources’ roll).
Two more, somewhat more distantly related links.
(We’re so screwed.)
ADDED: More on this topic at Charlton’s place.
ADDED: Gregory Cochran’s ‘outliers’ argument against this thesis has as its core: “In another application – if the average genetic IQ potential had decreased by a standard deviation since Victorian times, the number of individuals with the ability to develop new, difficult, and interesting results in higher mathematics would have crashed, bring such developments to a screeching halt. Of course that has not happened.”
I would have found it profoundly confidence-crushing if Cochran had simply said: the collapse of a complex trait on this scale, in this time-span, is inconsistent with everything we know about population genetics. The argument he relies upon instead, while far more elegant, is also much less persuasive (see the excellent comment thread at his site). As Dave Chamberlin notes, the parallel increase in assortative mating over the period in question means that assuming a stable standard distribution (variance) might not be safe. An increasingly heterogeneous population would to some degree shield its outliers from averaging effects.
Compared to the evidence mustered in support of the IQ collapse thesis, it is hard to be impressed by the rather impressionistic claim “Of course that has not happened.” Up to the mid-20th century — the era of Gödel, Von Neumann, and Turing — this might indeed have been irresistible, but today? Charlton’s counter-argument seems by no means risible. How sure are we that mathematics has not “collapsed” — at least down to the level of ‘normal’ (rather than ‘revolutionary’) science? What was the last mathematical break-through that mattered dazzlingly to the world?
ADDED: Mangan adds a significant complication.