Progressive is regressive in that it punishes performance and rewards mediocrity and laziness. There is no reason for a progressive tax. It is theft.
I get so annoyed over the way that term "progressive" is misused by leftist demagogues. It refers, of course, to rates that become progressively higher at higher income levels. It is not meant to imply that those that favor such rates are forward thinking, unlike the Neanderthals who favor a regressive rate structure. I know you know this but I had to rant. :)
It seems to me that a "flat tax" would be every man paying the same amount. Everyone pays $3,000. per year, for example. A flat tax rate, on the other hand, seems seems quite effective at soaking the rich, if that is one's goal. At 10%, the man making $10,000 pays $1,000, and the man making $10,000,000 pays $1,000,000, a thousand time more! Where is it written in stone that fairness demands progressive rates?