Here is another perspective on the social justice/equal opportunity issue. It is not the premise of social justice that *all* students have the same potential - it is that the *distribution* of potential is the same among different subgroups of the population. Take, for example, socioeconomic status as a variable.
Consider the following logic:
(1) Intelligence is positively correlated with income and other measures that comprise SES.
(2) Intelligence is highly heritable. One finds estimates of about 75% in the U.S.
(3) Given (1) and (2), the children of high-SES parents are ON AVERAGE more intelligent than those of low-SES parents.
The idea that all subgroups have the same average potential is theoretically implausible, and it does not appear to be empirically true, either. There is an interesting graph
at
http://yglesias.thinkprogress.org/2011/03/edunihilism-and-early-childhood/ in a post "Edunihilism and Early Childhood" by Matt Yglesias . Achievement test gaps between children of less-educated and more-educated mothers are largely in place by age 3. That does not prove the gaps are largely genetic, but it is suggestive.
