I’ve been enjoying the back and forth between Stephen Walt and Dan Drezner over whether America’s position is waxing or waning in terms of its ability to influence world affairs (Andrew Sullivan has been helpful enough to collect the links; start here and work your way back). I’m inclined to agree with Stephen Walt’s overall assessment that to ask whether America is “in decline” or “still number one” is to ask the wrong question. But I think the specifics of his retort to Drezner are somewhat lacking.

In 1950, the United States was the overwhelming leader of the West, and accounted for the overwhelming preponderance of global GDP. The world was bi-polar, with the United States confronting the Soviet Union and its allies across the globe. In that competition, the United States was decidedly at an advantage. China, in 1950, was a dirt-poor country only intermittently able to feed itself. But in 1950, America and China fought in Korea, and the Chinese were repeatedly able to inflict substantial reverses on the American and allied armed forces in a war that was ultimately fought not to victory but to a stalemate.

There’s very little question today that, if war came again to the Korean peninsula, the result would be a rapid and overwhelming victory for the American-allied South – albeit at a horrific cost in civilian life. There is no country on earth remotely capable of inflicting the kind of damage that we suffered in Korea. But the United States just fought a war in Iraq, and are still fighting a war in Afghanistan. And it is difficult to articulate any set of substantial war aims that have been achieved by our activities. (Iraq remains unstable, and inclines toward hostile Iran; Afghanistan remains downright chaotic, and the most likely endgame there is a return to some measure of power by the regime we fought to overthrow. We did eliminate Bin Laden – a vital war aim – but that operation was executed in Pakistan.)

From 1950 to 1980, America’s relative share of global GDP declined steadily, while the relative share of America’s former adversaries, Germany and Japan, grew steadily. By 1980, fears had been voiced for some time that America was in decline, and that these rival economic powers were in ascendance. The German economic model retains many admirers, and Japan has actually been rather more prosperous over the past twenty years than the aggregate GDP statistics would suggest. But on a relative basis there’s no question that the United States has outpaced Japan economically over the past twenty five years. Meanwhile, though, China, India, Brazil and other countries have risen to new prominence. For America to retain its relative economic position over the next twenty-five years would require truly extraordinary growth on America’s part or the tragic failure of economic development in much of the rest of the world.

The obstacles facing other powers in any attempt to rival America globally are much more substantial than the obstacles facing America in trying to retain its position of relative supremacy. China, for one, faces a brutal demographic crunch in the next couple of decades, while India’s social and economic development still lags very far behind China’s, to say nothing of the developed world. But to say that other major countries are unlikely to be in any position simply to scorn the United States is not to say that they are going to be obliged to bow to our interests. And even when our interests are broadly aligned, we can’t necessarily make other countries do what we want. The biggest economic risk to the United States right now is the unraveling of the Euro, which is the currency used by a collection of American allies, and there’s not really anything we can do about it. Patting ourselves on the back for doing “better” than Europe in handling the financial crisis doesn’t make me feel any better when we – inevitably – suffer for their failures just as they do for ours. The salient fact is: we are no longer big and dominant enough to be indifferent.

And then there’s the question of the “zone of chaos.” Among the nice things about the contemporary world are included: that there are no large, powerful revisionist powers (China is neither powerful enough nor following a radical revisionist strategy comparable to the Soviet Union or the Axis powers, and Iran is not ever going to be in that league in any conceivable world); that most of the other highly developed countries are our formal allies; and that the cost/benefit ratio for aggressive war for a developed power is about as negative as it’s ever been. These days, the only conceivably profitable wars for resources are being fought in extremely underdeveloped places like central Africa. The nasty thing about the contemporary world is: there are a lot of people in underdeveloped places – a lot more than there used to be. From a military perspective, a great deal of what being a “global hegemon” might mean is having the privilege of being expected to manage these zones of chaos as best we can. We might seek – or reject – that job for moral reasons, but unlike our relations with relatively stable states it’s very unclear how, in this area, maintaining our hegemonic position produces a positive feedback that, in turn, enhances that position.

What all this means is: even if – as is likely – America stays “number one,” this doesn’t mean what the enthusiasts for hegemony want it to mean. Which, I think, is Walt’s fundamental point. If we want to be the leader in providing genuine public goods through power projection – freedom of the seas, for example – we are very capable of can easily afford to continue doing that. If we define our interests somewhat narrowly, that also puts us in a good position – if we want it – to be the sponsor of regional security arrangements, such as might wind up obtaining in Southeast Asia depending on how China behaves. When other powers trust our intentions more than those of a regional threat, and we have the power in reserve to balance effectively, of course other powers will seek good relations with us. What we’re not in a position to do is injudiciously throw our weight around and expect the world to simply accept it, which is precisely the way the previous Administration talked on a regular basis, and the way it behaved in Iraq, and how this Administration talks (and behaves) at least some of the time. Walt’s “balance of threat” thesis applies to us as well as to other powers. Under these circumstances, if we want to maximize the long-term value of our position of preeminence, it might not be wise to continue to assert our rights to the purple of global hegemony.

We may well remain the biggest kid in the sandbox for a very long time, but the sandbox is much more crowded than it used to be.