Earlier quoted context omitted.
I like the implied reasoning saying that "Other governments are willing to take a bigger slice of the fruits of your labor, so you have no grounds to complain." Except I don't, actually.
That's not the logic I'm employing, though I see why you think it is. I'd rather point out that those 26 other countries do not appear to suffer a deficit of academics like Mankiw, despite a much stronger incentive for them not to take similar speaking engagements. Of course, the bigger flaw with Mankiw's argument is that it evades the point of those taxes, which is that they buy things that our society has deemed wo…
Again, it may very well be more than the claimed 90% tax rate. I also realize the professor has a vested interest (for several reasons) in knocking the tax cut expiration. But the United States tax system is complex beyond belief and I think any comparison with other countries is never simple.
Edit: Or higher than the 'real' tax rate if the professor is pushing the numbers in his favor (likely).