How Economic Inequality Harms Societies
In this Ted Talk from 2011 Richard Wilkinson, Wilkinson describes the correlation between income inequality and social problems.
A common misperception is that the richer a country is, the better-off the citizens of that country are. Wilkinson disproves this notion and shows that there is no correlation between life expectancy and the average income of a country.
Instead, he shows that there is a strong correlation between income inequality and a number of social problem that he and his team combined and called the "Index of Health and Social Problems". This correlation is true for each of the social problems he mentions: life expectancy, math & literacy, infant mortality, homicides, imprisonment, teenage births, trust, obesity, mental illness - including drug and alcohol addiction and social mobility. He finds that "the more unequal countries are doing worse on social problems."
Wilkinson takes his analysis a step further and looks at the American states. The conclusion remains the same - the more unequal the state, the worse it performs on the social measures.
He concludes with the notion that "We can improve the quality of human life by reducing the differences in income between us."