A question I often hear people ask is: Why should we care about a country’s total gross domestic product? After all, India has a total GDP many times that of the Netherlands, but the Netherlands has a much higher standard of living. Shouldn’t we concern ourselves only with per capita GDP -- or some other more accurate measure like median per capita income?
This isn't just an academic question -- it's important for policy. Japan’s falling population won’t be catastrophic for its per capita GDP, but it will drastically decrease the total. Should Japan be trying to boost population size, by increasing fertility and letting in immigrants? If you think that only living standards matter, then maybe this just isn’t important.