The actual justification isn't to redistribute like Robin Hood. It is for the simple fact as one earns more the slower they spend it. A grandma in the projects spends quickly and locally. The wealthy spend slowly and often elsewhere much later. It's about economic growth, when the tax code was progressive the economy grew faster. I majored in Economics, the spending by economic quintiles is vastly different. The bottom 40% have an income multiplier of nearly 11 times more in 12 months. The top 20% spend so slowly on average, that their spending multiplies by less than once more overall over 12 months past their earning. Art, luxury items, far away investments and so on. We've been cutting taxes for them the last 40 years and economic growth has stagnated and with their extra loot they have circumvented campaign finance limits. This isn't about taking from one individual to give to another, that isn't going to sell, as too many foolishly expect to become rich. This has to be sold to fuel economic growth to regrow and expand the middle class.