David Runciman reviews The Spirit Level: Why More Equal Societies Almost Always Do Better by Richard Wilkinson and Kate Pickett, in the London Review of Books:
The argument of this fascinating and deeply provoking book is easy to summarise: among rich countries, the more unequal ones do worse according to almost every quality of life indicator you can imagine. They do worse even if they are richer overall, so that per capita GDP turns out to be much less significant for general wellbeing than the size of the gap between the richest and poorest 20 per cent of the population (the basic measure of inequality the authors use). The evidence that Wilkinson and Pickett supply to make their case is overwhelming. Whether the test is life expectancy, infant mortality, obesity levels, crime rates, literacy scores, even the amount of rubbish that gets recycled, the more equal the society the better the performance invariably is. In graph after graph measuring various welfare functions, the authors show that the best predictor of how countries will rank is not the differences in wealth between them (which would result in the US coming top, with the Scandinavian countries and the UK not too far behind, and poorer European nations like Greece and Portugal bringing up the rear) but the differences in wealth within them (so the US, as the most unequal society, comes last on many measures, followed by Portugal and the UK, both places where the gap between rich and poor is relatively large, with Spain and Greece somewhere in the middle, and the Scandinavian countries invariably out in front, along with Japan). Just as significantly, this pattern holds inside the US as well, where states with high levels of income inequality also tend to have the greatest social problems.
More here.