Science vs. Pseudoscience: In an interesting article in The New Republic, USC/NYU professor Nathaniel Frank discusses scientific findings on gay marriage and debunks the shoddy social science one often hears activists invoke. Unfortunately the article is subscription-only; here are some key points:

Perhaps the most prominent scholarly argument against same-sex marriage comes courtesy of Stanley Kurtz, a research fellow at the Hoover Institution. Since February, Kurtz has taken to the pages of The Weekly Standard, National Review Online, San Francisco Chronicle, and The Boston Globe to argue that evidence from Scandinavia shows that recognizing same-sex unions has nearly destroyed the institution of marriage there. The "evidence is in," Kurtz concludes. "Marriage is dying in Scandinavia," where "de facto same-sex marriage" has existed for over a decade.

Kurtz offers statistics showing that rising proportions of children in Sweden, Norway, and Denmark are now born out of wedlock. Although he concedes that many factors have contributed to this development, he insists that the creation of "same-sex registered partnerships" has "locked in and reinforced the separation between the ideas of marriage and parenthood, thereby accelerating marital decline" by weakening the cultural imperative to wed before giving birth. Kurtz's argument is not that gay marriages would prompt existing straight couples to end their marriages, just that the symbolic damage done to the institution by letting gays join it would deter younger couples from bothering to wed: "By getting Americans used to a strong separation between marriage and parenthood, gay marriage would draw out these trends and put us firmly on the path to the Scandinavian system."

Alas, Kurtz's conclusions are suspect on their face--for the simple reason that Scandinavia does not have gay marriage, merely a marriage alternative available only to gays. (Kurtz clearly knows this, because at times he correctly calls them "registered partnerships." But, then, inexplicably and inaccurately, he slips into calling them gay marriages.) That complication aside, he offers zero evidence suggesting that gay partnerships have driven down marriage rates among heterosexuals in Scandinavia. At best, Kurtz struggles to show a correlation, much less a causative effect, between gay partnerships and the "disappearance" of marriage. Co-habitation and out-of-wedlock births, we are told, "closely track the movement for [what Kurtz calls] gay marriage." In one liberal county in Norway where "gay marriage has achieved a high degree of acceptance" (never mind that it remains illegal), marriage rates are in decline.

But to suggest these correlations prove that recognizing gay unions has hurt marriage is simply shoddy social science. If gays are to blame for Scandinavia's marital decline, how do we explain another trend closer to home: In the United States, the number of unmarried, co-habiting couples increased tenfold from 1960 to 2000. And all of this with no gay marriage, no registered partnerships, not even civil unions, which only came into existence in a handful of states after the 40 years of data in question. If anything, the emergence in the West of both registered partnerships for gays and the possibility of gay marriage itself are more likely a result, not a cause, of liberalizing attitudes toward marriage, themselves a product of evolving views toward women, divorce, and contraception, along with a host of social issues (including a vibrant social safety net) that have made being single a more attractive option. But, however you feel about that proposition, Kurtz's claim that he can now "answer the key empirical question underlying the gay marriage debate" is utter nonsense.

Worse, Kurtz's conflation of gay partnerships and gay marriages is hardly a trivial mistake. Kurtz begins from the premise that co-habitation undermines marriage by offering an alternative arrangement for child-rearing, thus removing the social stigma of out-of-wedlock birth and severing the link between marriage and parenthood. He then argues that "gay marriage" further erodes the link between marriage and parenthood, making a bad situation even worse: "Scandinavian gay marriage," we are told, has sent the message that "virtually any family form, including out-of-wedlock parenthood, is acceptable."

But, once again, there is no gay marriage in Scandinavia, only registered partnerships. And these arrangements by definition sever the link between marriage and parenthood, not because gays don't have children--they do--but because they are denied the right to marry and are thus consigned to co-habitation. If they have kids, this means they're sentenced to unmarried parenthood. By contrast, if gays could marry, many of the children living with out-of-wedlock gay parents would instead be living in married households, and the link between marriage and parenthood would be restored. The only thing Kurtz's data really show is that formalizing a new arrangement of co-habitation is correlated with increased co-habitation rates.

I've always been surprised how many people repeated the claims about Scandinavia, apparently assuming that correlation=causation.

[a study by USC professors Stacey and Biblarz] decisively rebuts the idea that growing up with gay parents is harmful: Such children "display no differences from heterosexual counterparts in psychological well-being or cognitive functioning," they write. In addition, Stacey and Biblarz find that gay parenting "has no measurable effect on the quality of parent-child relationships or on children's mental health or social adjustment." This, as it happens, was also the determination of the American Psychological Association (APA) after an extensive 1995 review of the literature on gay families. Children raised by gay parents, the APA concluded, are not "disadvantaged in any significant respect relative to the children of heterosexual parents." The American Academy of Child and Adolescent Psychiatry echoed this finding in its 1999 statement opposing discrimination against gay parents. Ditto the American Academy of Pediatrics in a 2002 policy statement, saying children of gay parents have "the same advantages and the same expectations for health, adjustment, and development" as those of heterosexual parents. Indeed, not a single reputable study shows any harm whatsoever to children living in same-sex-headed households.