It is a well known fact that in the United States that opposition to abortion tends to be concentrated among the most religious segment of the population. It is also a fact that the more secular nations tend to be more accepting of abortion than the religious ones. But what about the trends within nations? Yesterday on Gene Expression I posted a chart which shows that the proportion of Catholics who oppose abortion is strongly correlated with the proportion of the other major religious group who oppose abortion. All things equal there was an international tendency for Catholics to be somewhat more anti-abortion than non-Catholics, but a far better predictor of attitudes was not religion but nationality. In other words Catholic Germans resembled Protestant Germans while Catholic Chileans resembled Protestant Chileans.
But what about religion and irreligion more generally on the international level? That is, do religious and irreligious people within a nation tend to correlate in their attitudes toward abortion? Do atheists in Germany resemble religious people in Germany more than they do atheists in Nigeria? I used the same methodology is in the Gene Expression post. I used The World Values Survey. I looked at Wave 5 and Waves 3 & 4 separately, so the latter are aggregated. This means some nations show up twice in the data set. Additionally I discarded any nation where the sample size for atheists was 10 or less. There is a variable which asks people to rate their attitude toward abortion on a 0 to 10 scale in terms of if it is justifiable, 0 = “never justifiable.” That is the proportion in the data, abortion is never justifiable. Additionally for each nation there is a breakdown into three categories, “religious person,” “not a religious person” and “convinced atheist.” So the raw data below you see rows which have nations, and three columns for each category. All the numbers are percentages of those who believe that abortion is never justifiable.
Below are two scatterplots. Each data point represents a nation.
1) It is clear that religion correlate with opposition to abortion in the vast majority of nations.
2) But, the attitudes of religious people and non-religious people track each other so that the irreligious in nation X may oppose abortion much more than the religious in nation Y.
3) The small sample sizes for “convinced atheists” was probably the reason that you see more of a residual in that plot than in the one which included those who were “not religious.”
Raw data below the fold.