I think natrius was saying your definition of 'left' is skewed right. Progressive taxation enjoys broad support and so is by definition centrist and not left.

This is a definition of left/right that depends on public opinion and not who controls the discourse. You could definitely argue that progressive taxation as defined by popular discourse in America is left. But that would be ceding too much power to the minority which controls political discourse in America, IMHO.

I think many people would think of progressivism as two sheep and a wolf voting on what to have for dinner.