A month ago, the polymath looked at changes in the religious composition of the two major US political parties over time. The short version is that Catholics are becoming a relatively smaller piece of the Democratic party, while Protestants are taking it in the chin in both parties to make room for those who lack any religious affiliation.
As someone whose firsthand memory of politics extends back only to the 2000 Presidential election, I'm interested in how partisan positions on major social issues have shifted over the last several decades. The accusation is commonly made by libertarian types and those on the 'religious left' that the Religious Right has steadily moved to overtake the GOP. Implicit in this charge is the insinuation that the socially conservative positions these theocons hold have come to be shared by a greater percentage of Republican voters than before the hijacking. Conversely, National Defense Democrats of a pious disposition, like Zell Miller, are said to have been abandoned by an increasingly secular, progressive Democratic party.
The social positions of the two parties feel pretty static to me, but that's a result of my limited frame of reference. I realize history didn't start yesterday, or even the turn of the last millenium. Fortunately, the GSS is a useful tool for helping me fill myself in. The change over time in positions on five major social issues can be tracked back to the seventies. The following graphs depict those changes among self-identified Republicans, Democrats, and indepedents* over the last 35 years.
Other than on the issue of school prayer, the partisan divide has increased modestly over time, lending some truth to the oft-repeated claim that the US is becoming increasingly polarized along political lines, though things do not appear to have changed that much. Partisan alignments on four major social issues have remained pretty stagnant over the last few decades.
The issue of abortion, by contrast, has undergone some shifting along partisan lines. Up to the end of the eighties, there was scarcely a distinguishable difference between Republicans and Democrats on the question, with Republicans actually tending to be slightly more supportive of the right to an abortion for rape victims than Democrats were. That has changed over the last couple of decades, to the extent that one in three Republicans now support granting human rights to the developing fetus of a woman impregnated via rape (and in my view imprudently serving up the rapist with a Darwinian success he shouldn't be permitted to enjoy).
Support for marijuana legalization has crept up across the board from its lows during the crack epidemic of the eighties and early nineties. Independents are generally more supportive of legalization than even Democrats are. Views on capital punishment and wealth redistribution** have reliably retained their partisan alignments, and the distance between Republican and Democratic positions on them have increased. Opposition to the 1963 US Supreme Court ruling in favor of Schempp has declined a bit for each group but the slight partisan divide has held fairly steadily.
GSS variables used: YEAR, PARTYID(0-1)(2-4)(5-6), GRASS, ABRAPE, CAPPUN, EQWLTH, PRAYER
* Respondents are asked to describe their party affiliation by choosing among eight possible options. "Other party" is ignored for the purposes of this post. I've elected to include "Independent, near Republican" and "Independent, near Democrat" in the independent category, with "Not strong Republican/Democrat" and "Strong Republican/Democrat" the two potential choices earning inclusion under the Republican/Democrat classifications. This yields a 36% Democrat, 25% Republican, and 36% indepdent split, which seems preferable to only classifying unadultered independents (15%) as, well, independents. And the respondents are, after all, self-describing as independents leaning toward one party or the other, not partisans leaning toward the center.
** The representation is computed from responses on an inverted (to facilitate viewing the graph) seven-point scale, with a 7 representing the highest level of support for the government reducing income differences and a 1 representing the lowest level of support for it. Annual responses are averaged by year for each political classifcation.