If more financially homogeneous (i.e., less wealth skew) societies are happier, would you expect more culturally homogeneous (i.e., shared norms/history) societies to be happier?
Maybe we are measuring happiness incorrectly. Instead of most people being happy, what if we made a small number of people REALLY happy? Maybe the 0.1% are so happy that it balances out the sadness of everyone else?
As sarcastic as this is, you still end up with the same just less intensity. If statistics and estimation are involved, this proposed happiness index will leave some behind and end up with everybody the same.
If you used the median then only actions which affected the utility of someone in the top 50% and bottom 50% would have any moral impact. e.g. two miserable people torturing each other or helping each other would be neither good nor bad, since the median would not change.
Neither of those seem that important at the country level as long as it's true at some level somewhere.
If you're in a small country richer people in the neighboring country seem about as likely to have the same effect. On the other hand, if you're in a large country and they live in a different city you're not running into them.
An issue with nationalism is that nations are in some ways very real and in some ways fake.
I would expect this to be true to some degree, with declining marginal returns to homogeneity after some point maybe even tipping negative with too much homogeneity.
There seems to be a lot of countries that are culturally homogenious, and yet they are poor and miserable. So it does not seem to check out.
It is also not clear how one should calculate this - for example you could have white americans of german dissent violently disagreeing in issues of Trump, or hell, this about civil war. You could have people of different background hold very similar opinions.
My general hypothesis is that most people are happier when they feel typical or normal (even when they claim to value being different). This seems to be the essence of lots of advertising. To increase their own happiness, most people want to "normalize" everyone around them (levels of wealth, values, etc).
Perhaps national happiness (since that is the level of society being discussed) is a joint function of cultural AND financial homogeneity? Many poor countries with high cultural homogeneity have tremendous financial heterogeneity (e.g., wealthy strongmen and their lackeys), which leads to unhappiness.
There are more ways that people want to be normal than just cultural and financial. For example, I would also posit that people with more common personality traits are probably happier. However, money and culture seem to cover a large fraction of how people perceive normality.
