Those are all good answers, but for a slightly different argument. What I thought was novel about the argument in the article, was that it attacks the issue of taxing the rich from another position. It somewhat sidesteps or anticipates our usual counterarguments and argues that the volatility of a tax base that relies on the income of the wealthy is problematic, not so much that taxing the wealthy in and of itself stifles the economy (though there are hints to that in the article).
Bryan
^^^^^ CB: The rich tax base might be "volatile" but for every rich person who loses their fortune isn't there a new rich person to tax, by and large. The size of the rich population stays the same, or does the proportion of wealth held by the rich stay the same or grow in recent years ?