In this paper, the relation between the equality of income distribution and sustainable development is discussed. This issue is elaborated using theories of justice of John Stuart Mill, John Roemer, John Rawls and Amartya Sen.

The majority of the world's poor, by income poverty and multi-dimensional poverty, now live in countries officially classified by the World Bank as middle-income countries. Of course nothing happens when a country crosses a (somewhat) arbitrary threshold in per capita income but it does matter...