A NY Times opinion piece from Harvard law professor Noah Feldman makes this argument: “The decline of the Protestant elite is actually its greatest triumph.” Feldman explores the changes in the Supreme Court (the appointment of Kagan would make it 6 Catholics, 3 Jews) and Princeton (“As late as 1958, the year of the “dirty bicker” in which Jews were conspicuously excluded from its eating clubs, Princeton could fairly have been seen as a redoubt of all-male Protestant privilege).
So what changed? Feldman provides some reasons: “the anti-aristocratic ideals of the Constitution,” education was an important defining trait for WASPs so opening up universities was a big step, and the American value of fair play. The result:
Together, these social beliefs in equality undercut the impulse toward exclusive privilege that every successful group indulges on occasion. A handful of exceptions for admission to societies, clubs and colleges — trivial in and of themselves — helped break down barriers more broadly. This was not just a case of an elite looking outside itself for rejuvenation: the inclusiveness of the last 50 years has been the product of sincerely held ideals put into action.
These may be accurate reasons. But they seem to ignore the historical context: something happened in the 1960s that changed institutions like Ivy League schools and led to a very different looking Supreme Court. In that decade, the Civil Rights Movement plus an explosion in higher education for the burgeoning US population plus higher rates of immigration from non-European locales plus cultural change (rock ‘n’ roll, television, more open questioning of authority, etc.), changed, or at least began to change, the socioeconomic status of WASPs.