We are often told that ethnic diversity is a strength. Given this, we should expect that diverse countries are, in various ways, better than homogenous ones. Let’s take a look at how accurate this expectation is.
To look at this question empirically, I used data on life expectancy, life satisfaction, and national wealth from the 2016 World Happiness Report and data on ethnic diversity from Alesina et al. (2003). Conceptually, ethnic diversity is defined as the probability that two people randomly selected from a nation will not be of the same ethnic group.
As it turns out, the more ethnically diverse a nation is the less happy its population tends to be. Across 129 nations, the correlation between diversity and national life satisfaction is -.40 which is a moderately strong negative correlation by conventional standards.
Ethnically diverse nations also tend to be poorer. The correlation between diversity and national wealth across 129 is -.55 which is a strong negative correlation by conventional standards.
Finally, we have health. The more diverse a nation is the lower its life expectancy tends to be. Across 130 nations, the correlation between diversity and life expectancy is -.66 which is a very strong negative correlation. (There was life expectancy data for one more country than there was for life satisfaction or wealth).
Diverse nations tend to be less healthy, less happy, and less wealthy, than homogenous ones. Of course, these are just correlations, but correlations are evidence (though not proof) of a causal relation. Here is a brief account of one plausible hypothesis about why these variables are related which has supporting evidence from various studies:
Experimental, longitudinal, and correlational, evidence shows that ethnic diversity damages how well people get along with one another. A person’s social life, in turn, is thought to be a key determinant of how happy they are. This may be why ethnic diversity negatively correlates with national life satisfaction.
Experimental and correlational evidence also shows that group productivity is damaged by ethnic diversity. Correlational evidence further shows that distrust in others, which ethnic diversity creates, increases the degree to which people favor government control over the economy. These are both plausible mechanisms by which diversity might hamper national wealth.
This decrease in national wealth could, in turn, also cause a further decrease in national life satisfaction.
We don’t need to posit anything more to explain life expectancy. National poverty and unhappiness are not good for a person’s health, and this may explain why diversity negatively correlates with life expectancy.
Advocates of diversity must argue that these correlations are in some way misleading and present a more compelling explanation for them than I have here in order to make a convincing case for allowing our nation (or your nation) to become more diverse.
Of course, they won’t. Instead, they will try to silence rational debate with cries of racism. But facts don’t care if liberals call them racist, and the fact of the matter is that diversity looks a lot more like a national weakness than a national strength.