Simply put, liberals have a big baby problem: They're not having enough of them, they haven't for a long time, and their pool of potential new voters is suffering as a result. According to the 2004 General Social Survey, if you picked 100 unrelated politically liberal adults at random, you would find that they had, between them, 147 children. If you picked 100 conservatives, you would find 208 kids. That's a "fertility gap" of 41%. Given that about 80% of people with an identifiable party preference grow up to vote the same way as their parents, this gap translates into lots more little Republicans than little Democrats to vote in future elections. Over the past 30 years this gap has not been below 20%--explaining, to a large extent, the current ineffectiveness of liberal youth voter campaigns today.Of course, Brooks is ignoring the potential impact of immigration on the American body politic. I suspect that both parties are not, though. Expect both immigration and low liberal birth rates to become high priorities for Democrats in the near future.
Alarmingly for the Democrats, the gap is widening at a bit more than half a percentage point per year, meaning that today's problem is nothing compared to what the future will most likely hold. Consider future presidential elections in a swing state (like Ohio), and assume that the current patterns in fertility continue. A state that was split 50-50 between left and right in 2004 will tilt right by 2012, 54% to 46%. By 2020, it will be certifiably right-wing, 59% to 41%. A state that is currently 55-45 in favor of liberals (like California) will be 54-46 in favor of conservatives by 2020--and all for no other reason than babies.
The fertility gap doesn't budge when we correct for factors like age, income, education, sex, race--or even religion. Indeed, if a conservative and a liberal are identical in all these ways, the liberal will still be 19 percentage points more likely to be childless than the conservative. Some believe the gap reflects an authentic cultural difference between left and right in America today. As one liberal columnist in a major paper graphically put it, "Maybe the scales are tipping to the neoconservative, homogenous right in our culture simply because they tend not to give much of a damn for the ramifications of wanton breeding and environmental destruction and pious sanctimony, whereas those on the left actually seem to give a whit for the health of the planet and the dire effects of overpopulation." It would appear liberals have been quite successful controlling overpopulation--in the Democratic Party.
Brooks's essay is instructive in one point, though, it dispels the myth that young people of today are not "turning more conservative." They're being born this way instead. If the GOP wants to keep them voting that way, they'll need to keep their rhetoric more futuristic libertarian conservative (or my preferred term "liberal conservative") and less traditionalistic conservative.