Last week, The National Interest (Online) published a critique of U.S. grand strategy in Asia by my friend and colleague John Glaser. Harry Kazianis, a former editor at TNI who now divides his time between the Potomac Foundation and the Center for the National Interest, posted a rejoinder and Glaser has since responded here.

Together, the pieces reveal a useful debate over primacy, writ large, and all three are worth a careful read.

Calling Glaser’s idea “Unthinkable,” Kazianis asked:

And what’s so bad about America’s so-called primacy in Asia in the first place? Glaser, at least in my view, makes it sound like the Asia-Pacific is some large American vassal state that it should relinquish control of. It should be clear for anyone to see that Washington is the provider of many important net public goods—like those all-important security alliances, nuclear umbrellas and protected sea lanes that allow trade to thrive.

His clinching argument, it seems, is that we should continue with our present grand strategy in Asia (and elsewhere, implicitly) because it’s the strategy that we have, and it’s worked fairly well. Why change now?

Kazianis quotes former Under Secretary of Defense for Policy Eric Edelman who, in 2010, offered up this fairly typical defense of U.S. grand strategy. “The concept of Primacy,” Edelman wrote, in a paper (.pdf) for the Center for Strategic and Budgetary Assessments:

has underpinned U.S. grand strategy since the end of the Cold War because no other nation was able to provide the collective public goods that have upheld the security of the international system and enabled a period of dramatically increased global economic activity and prosperity. Both the United States and the global system have benefitted from that circumstance.

I would take issue with two of Edelman’s claims, and, by extension, those of Kazianis and other of primacy’s defenders:

1) Correlation is not causation. While it is true that the long peace has coincided with U.S. primacy, that does not prove that U.S. primacy was the sole (or even main) cause of it. Some attempt should be made to account for the other possible explanations for the absence of great power war since 1945, e.g. nuclear weapons, economic interdependence, and the end of formal empires.

2) Circumstances change. Even if it were true that U.S. primacy was the main factor explaining the security of the international system during the last quarter century, to describe what we have done for the roughly 25 years since the end of the Cold War does not, by itself, justify what we should do for the next 25 years, or more. The U.S. share of global economic output has fallen sharply since the end of the Cold War. When looking at GDP by Purchasing Power Parity in the IMF’s most recent data set, for example, the U.S. share stood at 22.5 percent in 1989; the estimate for 2015 is 15.9 percent. Whatever statistic one chooses to use, it is clear that the burden is growing heavier on a single country. And those trends are unlikely to reverse themselves. The U.S. share is expected to dip below 15 percent by 2020.

I will stipulate that no single country could have done what the United States did in terms of providing global public goods in 1995 — or 1975 or 1955, for that matter. I doubt that a single country — including the United States — can do it forever. Forever is a long time.

It may be true that some number of countries — be it 5 or 10 or 50 — might be able to collectively muster comparable capabilities in the future to ensure that the burdens of global governance don’t fall exclusively on the shoulders of American troops and American taxpayers.

We are unlikely to reach that possible alternative future of greater burden sharing, however, if the United States clings to its present grand strategy and continues to discourage other countries from defending themselves and their core interests.