If it is not known how much social class is due to genetic and how much to other factors, then it cannot be assumed that intervention will move things towards a ‘fairer’ position. This may explain the reactions of writers such as Stephen Jay Gould to The Bell Curve.*
One of the central arguments of The Bell Curve is that America’s upper class is an elite with relatively high average IQ, which has arisen because intelligence is partly heritable. Gould asserts that this argument requires
the validity of four shaky premises, [i.e. intelligence] must be depictable as a single number, capable of ranking people in linear order, genetically based, and effectively immutable. If any of these premises are false, the entire argument collapses.**The validity of The Bell Curve’s explanation of class does not depend on intelligence being ‘immutable’. Gould seems to be confusing questions of fact with questions of policy.
Nor does the explanation depend on intelligence being depictable as a single number. Whether intelligence, or ability in general, is heritable is a separate question from how well a single variable, such as IQ, is capable of measuring it.
* Richard Herrnstein and Charles Murray, The Bell Curve, Free Press 1994.
** Stephen Jay Gould, The Mismeasure of Man, Penguin 1997, p.368.