The original US income tax was a flat one of 3% for earnings over today's dollars of about 17k.
I wouldn't have a problem with that.
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The first income tax might have been on 1918 dollars starting at $17,000, but it was definitely not $17K in terms of 2008 dollars.
Adam Smith thought that wealthy people should pay more in taxes, at a higher rate.
There is no reason why they should not do this.
Every year, the wealthiest 1% owns a larger portion of money and property. The maldistribution of wealth in the US resembles that of Portugal and Mexico, and it is getting worse with each passing year. It is unhealthy for this country that a tiny minority own so much. It is even worse that this share is growing.
Taxation is the simplest way to deal with this problem. Obama simply wants to return to the taxation of the Clinton period.