The WORDSUM variable in the General Social Survey has a correlation of 0.71 with general intelligence. That is, IQ. As you can see in the figure above the distribution isn’t quite normal, though those with at least a college degree are skewed toward having higher scores. A 10 out of 10 means getting the definition of all 10 vocabulary words on the test correct. A 0 out of 10 means the converse.

It’s often illuminating to see how WORDSUM tracks social views. My rule of thumb is that if an overwhelming skew of the intelligent is toward one particular opinion, that will determine social policy. To me that explains why Creationism has had only spotty traction in this country’s public schools despite relatively broad avowed support for “equal time” in the classrooms in the interests of fairness. While the liberal elites are uniformly opposed to this, the conservative elites are divided.

Looking at attitudes toward abortion by intelligence also sheds some light why this political debate seems to be an eternal feature of the American landscape since the 1970s. I took WORDSUM and combined 0 to 4, 5 to 7, and 8 to 10. You can think of these as the “dumb,” “average”, and “smart.” Then I compared them to the ABANY variable in the 1980s and 2000s. This asks whether respondents think a pregnant woman should be allowed to have an abortion for any reason. The results are below.

As you can see, there is almost no change over the past generation.

Now what about gay marriage? You can probably guess where I’m going with this. No matter what intellectual Christians say I believe that this generation will come to pass such that the vast majority of Christians will accept gay marriage and their faith as compatible. More precisely, I believe that by the year 2100 the majority of the world’s Christian population is likely to be accepting of gay marriage.

Personally it has been interesting to see how attitudes have changed. In my own family individuals who were opposed to gay marriage ten years ago have now put a rainbow filter on their Facebook profile. More starkly, there are those I know from my adolescent years who are excited about gay marriage now. I grew up in a very conservative area (the county routinely votes 70 percent Republican), and remember debates in classrooms about ballot measures which we all termed “anti-gay”. Now some of those children who argued in favor of these measures are putting rainbow filters on their Facebook profiles!

So how have things changed? The GSS has a variable, MARHOMO, which asks if “Homosexual couples should have the right to marry one another.” It was asked in 1988, and then every few years from 2004 on. I combined those who strongly agree and agree that homosexual couples should have the right to marry. Below is a contrast between 1988, and the 2000s and 2010s, by WORDSUM.

So what’s next? Some liberals are now opening the debate about polygamy in the interests of fairness and justice (and more broadly construed polyamory). But as you can see from the map to the left polygamy is already legal in much of the world. This experiment has been done. The satirical slogans write themselves: “In the 7th century love for old rich men for many young women won! Back to the future.” A few years ago I put up a post, Monogamous Societies Superior to Polygamous Societies. That’s obviously a judgment that varies by where you stand. If you are the median human, it seems reasonable to me. Polygamous societies have been around for thousands of years. Almost always polygamous means polygynous, not polyandrous or polyamorous. We know the score. Yes, if you take a narrow liberal and liberal hedonic perspective about individual human flourishing it does seem unjust that those who love more than one individual can’t enter into legally binding relationships with those individuals. But the big picture is not so pretty.

Perhaps this time it will be different. But we have a track record of who enters into polygamous relationships, and who benefits. Polygamy allows extremely powerful and wealthy males to gain access to many women simultaneously. Of course serial monogamy and lack of fidelity show that this isn’t a very tight fix for the perceived problem. But the de jure laws which constrain elite individuals to one official marriage partner serves as a check on this phenomenon.

To put it more plainly, gay marriage has a huge impact on gays, and not much impact on straights (at least non-psychically). Gay marriage is basically an extension of a social-legal apparatus operative among straights to gays. Polygamy is different, in that it tinkers with major parameters of the machinery of the marriage, not simply who can partake. Polygamy does impact straight people, usually in situations where young males must scramble to accrue enough resources to be one of the fortunate men be able to have a wife, and perhaps a few to spare. From the perspective of women they have to consider the option of being a secondary wife of a rich man, as opposed to being the primary wife of a poor man. Enforced monogamy might be a behavioral strategy to dampen status competition and maintain social cohesion for both sexes (in the hunter-gatherer world a sort of serial monogamy was probably the norm). The basic thesis is that mass agricultural society allowed for the evolution of radical inequality, and the social norms of the ethical religions evolved precisely to bring the system back into balance.