Jonah — As the author of the piece referenced by Ross in his column and blog post to which you link, I should make clear that they concern a relative decline in power for the U.S. This is not speculative, but – as I describe in the piece, and have described earlier in NR — is historical fact. The U.S. position in September of 1945 was incomparably better than it is now. Even as late as 1965, though relative decline was underway, this was still true.
By the 1970s, the reindustrialization of Europe and Japan, plus changes such as the oil shocks, meant that U.S. relative power began to decline precipitously. The feeling of crisis at that time was not illusory. I believe that despite the rhetoric and popular perception, part of Regan’s genius was recognizing this, and finding a creative way to deal with it. Most forecasters in 1980, as per Reihan’s post, were predicting convergence between the U.S. and Europe, but our productivity revolution and population growth has allowed us to maintain our share of global GDP since 1980, while Europe’s has collapsed.
In some ways our relative decline is a return to the status quo ante prior to WWII. The huge difference, of course, is the transition of so much economic (and ultimately cultural and military) power to Asia. America is increasingly a nation among nations, and the “sole superpower” mythology represents an inflated sense of our position that, like all misperceptions, is likely to lead to preventable error.