Answering those questions could mean finding out that some women are already having more children than they wish, because they can’t access contraceptive or abortion services. Douthat doesn’t mention that having one of the highest teen pregnancy rates in the developed world has contributed to the U.S. having “more babies to the competition,” though that number, too, is in decline. The anxiety about U.S. demographic dominance over “the competition” (occasionally known as our allies) was a mostly unspoken subtext to the battles over reproductive rights, this year as before.

And it could also mean that as soon as women can have control over their fertility, they’re choosing to have fewer children than before. That’s evident among those immigrants that Douthat blithely claims the U.S. has a “willingness to welcome” (as long as they don’t demand citizenship, apparently, and for some of his conservative brethren, don’t have too many of the wrong kind of babies). The same Pew study to which Douthat pegs his argument found that among U.S.-born women, the birthrate declined by 6 percent between 2007 and 2010. For foreign-born women, it declined 14 percent; for Mexican immigrant women, it declined 23 percent.

But asking this question also means asking why some families that want to have more children than they do cannot — and why women, for whom childbearing is still a huge physical, social and financial cost, are choosing to have fewer children as soon as they have the tools. (Half of the pregnancies in the U.S. every year are still unintended, according to Guttmacher, but the women with the most resources to exert control over their pregnancies — “higher-income white women” — have an unintended pregnancy rate “at one third the national rate.”

Europe, where population hand-wringing is more familiar, offers plenty of data. (Its example also includes an entire body of literature, much of it written by conservatives on this side of the Atlantic, in terms less diplomatic than Douthat’s —  from Pat Buchanan’s pronouncement that “the rise of feminism spells the death of the nation and the end of the West,” to Mark Steyn’s assertion that parts of Europe were “too self-absorbed to breed,” to open fear of Muslim takeover.) As Michelle Goldberg notes in her excellent book, “The Means of Reproduction,” in Europe, too, liberal social values were blamed for the erosion of traditional family structures.

But, in fact, looking across countries, “a great body of research … shows that after a certain point of development, liberalism,” including legalized abortion, no-fault divorce, and laws meant to bolster gender equality, “doesn’t cause population decline — conservatism does.” That is to say, women look at what having more children will cost them, in financial but also professional and social terms, and make a rational decision to have fewer.

When countries like Sweden and France enacted such policies, plus generous family leave and daycare, these calculations weren’t simply based on feminist values (if they included them at all). Instead, they were keenly aware of rebuilding the population after the second World War, or meeting a shortage of workers without relying too heavily on immigration. As a result of those policies, Goldberg points out, they have higher birthrates than fellow European countries where women can control their fertility but that still have very sexist family structures — where, she says, some women may be on “birth strike” because they don’t want to be wholly consigned to traditional roles without help from partners or the state.  In  2003, Conservative British MP David Willetts came to the same conclusion, noticing that in Italy and Spain, “traditional family structure now leads to very low birth rates,” and remarked, “Feminism is the new natalism.”

We are very, very far from the Swedish example, and as rhetoric about exploding “entitlements” gets ratcheted up, probably getting further. Most conservatives would like to keep the demographic conversation tied to individual choices and as far away as possible from government policy, because it conflicts with other, more pressing goals. Just look at the nominal standard-bearer of the party this year, Mitt Romney, who proved sympathetic to the demographic decline argument at a speech at CPAC in 2008. ”Europe is facing a demographic disaster,” he warned. “That’s the inevitable product of weakened faith in the Creator, failed families, disrespect for the sanctity of human life and eroded morality.”

Douthat has correctly noted on his blog that Swedish social policies might be difficult to replicate here because Sweden is a small, wealthy and still homogenous country. Another way of looking at it is that in this country, even the most moderate social policies of inclusion are sneeringly called “gifts” to the presumed undeserving — women, people of color, immigrants — by the Republican nominee. Romney, with his five sons, enormous wealth and stay-at-home wife, hasn’t made the connection between one’s stable position in society and one’s desire to bring more people into it — but plenty of women already have.