T. M. Scanlon, Professor at Harvard University, describes the biggest four reasons why INEQUALITY is bad for society (Ideas.Ted.Com) 

1. Economic inequality can give wealthier people an unacceptable degree of control over the lives of others.

2. Economic inequality can undermine the fairness of political institutions.

3. Economic inequality undermines the fairness of the economic system itself.

4. Workers, as participants in a scheme of cooperation that produces national income, have a claim to a fair share of what they have helped to produce.

He highlights that- ”A justification for reducing inequality through non-voluntary means, such as taxation, needs to explain why redistribution of this kind is not just robbery.” and that is why he says ”No one has reason to accept a scheme of cooperation that places their lives under the control of others.” Visit Ideas.ted. com