Most of those other countries have pretty dismal mathematical output. Not only that, but the country with the best mathematical output of the ones you listed is the UK, which I think has the most "American" tax code. Whenever anyone produces a good mathematician, that mathematician seems to always come to the US. There's a reason Terrence Tao didn't stay in Australia. I'm not actually saying that this is because of our lower tax rate, I'm just pointing out what you likely already knew but disregarded to make a point.
Mankiw isn't a mathematician; he's an economist. Ranked by impact factor, Europe's universities are indeed outclassed by those of the US (attempt to control that by population and by the radically different systems those institutions operate under). I don't think you can really defend the claim that Europe's academic output is "dismal" compared to, like, the Earth, though.
No, but it is dismal compared to America's, which is what I said. And you said "academics like Mankiw", not "economists like Mankiw." Also, stipulating "by impact factor" seems like a sneaky way of suggesting that that's not a legitimate way to rank. That's fine; it's still true when you rank by "quality of output factor."
I chose impact factor because it's easy to look up. I suspect any other reasonable metric will produce similar results. I object only to the emotional word "dismal" here. Europe simply isn't a wasteland of academic economic thought.
