Most of you know that Europe (like Japan and South Korea) has very low fertility; below replacement even. One of the main explanations is that with the decline in religiosity it naturally follows that fertility will decline (the psychological or sociological proximate models vary). Atheism kills with its pessimism. On first blush I think this is plausible because I’ve heard so many post-religious individuals who simply assert that they could never have children because of the state of this world. That is, with various catastrophes on the horizon they would simply be perpetuating suffering. But think more closely on this…this isn’t a very novel or new perspective, it has cropped up among anti-worldly religious movements many times. Cathars were simply an extreme manifestation of this tendency. Additionally, when I surveyed data from the 2005 Eurobarometer the correlation between fertility and belief in god was weak. This makes sense when you consider that relatively religious nations such as Greece and Italy have lower fertilities than Sweden and France. That being said, the secular do generally have fewer offspring in the United States, and within population variation is a necessary complement to observations of between population variation.
So with all this in mind that I was interested to stumble upon a paper, Religion, religiousness and fertility in the U.S. and in Europe. The authors observe that the United States is much more religious than Europe as a whole, and the average American woman is much more fertile than the average European woman. From this many intellectuals have adduced that these two characters exhibit a causal relationship so that the greater fertility of American women can be attributed to their greater religiosity.
The authors note that one major problem with these analyses is that they aggregate Europe into a whole, when the reality is that there is a great deal of variation between nations. Specifically, fertility in southern and eastern Europe is far lower than in western and northern Europe. Additionally, they note in their analysis of the data that there is a different between period fertility and cohort fertility; it is the former where Americans have much higher values than Europeans. All this means is that American and European women tend to have around the same number of children (with Americans more), but American generation times are shorter, while European women enter into childbearing later.
General religiosity does correlate positively with fertility across Western nations. But, it does not seem to be fertility differences can be reduced as outcomes of differences in religiosity. From the paper:
For Europe as a whole, the estimate is that the fertility of women 18-44 would theoretically be 14 percent higher than its current level if church attendance were the same and 13 percent higher if the same importance were attached to religion. The theoretical increases are lowest for the North and highest for the West. The general picture is approximately the same for women 35-44 but only in the West is a substantial increase suggested (of 30 percent). The effects in different countries are a function of the differences in religiousness compared with the U.S., differences in current fertility and in the strength of the association between religiousness and fertility.
These are not trivial effects, but they point to more complex dynamics than the verbal treatments we find in the media. The variation on evidence within the data they analyze is to a great extent the most interesting aspect of the paper, because this is a paper which simply falsifies a general hypothesis. Instead of further comment, I will leave with you some important tables from this paper.
Note: Odds ratios are not complicated.
Addendum: The working paper can be downloaded in full at the link above.