I am interested in the philosophical implications of the two competing views of the Equal Protection Clause of the 14th Amendment.
It is often contended that an "individualist" view of what equal protection requires can't explain why only classifications based on race or sex require "heightened scrutiny," instead of the ordinary rational basis test. In some sense, this objection seems dead on. If what equal protection prohibits is the use of morally invidious classifications by state actors then certainly race and sex can't be the only two that we ought to be concerned about.
On the other hand, it seems like the "hierarchical" view is fraught with similarly serious problems. Who counts, nowadays, as a "discrete, insular minority" that equal protection ought to help? Does the fact that women are a majority mean that they should not benefit from heightened scrutiny, but men should? Or, if "discrete, insular minority" is just short-hand for politically handi-capped, how do we know how politically handi...
While it doesn't address the Equal Protection clause specifically, Tom Nagel's "A Defense of Affirmative Action" comes to mind here. It isn't so much the "minority" as the "insular" that calls for heightened scrutiny or preferential treatment. Nagel argues that a pervasive, deeply-rooted perception of the minority as an inferior social caste is the relevant factor. Thus when Nagel wrote in the 70s, African-Americans would be entitled to preference, but not women or, say, Asians. But in the 1930s, women would have been. Now, it might be Hispanics in the "lower caste" position. While a general perception of caste is about as vague as political handicap for use as a standard for interpreting a Constitutional clause, it seems to me that an important feature of both is the tendency to self-perpetuate in the absence of preference or at least heightened scrutiny.