On the Fall of Empires

I am watching the classic movie Ben Hur (1959) tonight.  In it, there is a scene were Judah Ben Hur confronts his Roman friend, Messala, about the Roman Empire.  He says, "Rome is an affront to God!  It is strangling my people, my country and the whole Earth.  But not forever and I tell you the day Rome falls, there will be a shout of freedom such as the world has never heard before!"  

There are many around the world, who for a wide variety of often contradictory reasons, would agree with replacing "Rome" with "America" in that statement.  Muslim fundamentalists, secular nationalists of various stripes and from various countries (outside the US of course where the nationalists would never say such a thing about America), many varieties of secular leftists from Marxists to environmentalist radicals to anarchists have invoked this kind of statement about the United States.  

This all raises two obvious questions.  First, is the United States declining as a super power/world hegemon?  Second, what happens when hegemons lose their position?

As for the first question, I think the evidence is mixed.  Certainly the US cannot impose its will on other countries without limits.  But then it never really could so pointing to that as evidence of decline isn't really fair.  It is also true that there are other countries in the world increasing in global influence both economically and militarily.  I'm thinking of countries like China, India and the EU (at least in the economic sphere).  But is power necessarily zero sum?  Does the rise in capabilities of some countries necessarily mean the decline of others?  I think that's a question that is very much open to debate and the answer depends on how you define power - a concept that is notoriously slippery.  If power is the ability to do x y or z, it is not necessarily zero sum so long as no other country can prevent their doing it.  Nuclear weapons place limits on what countries can do but also on what countries be prevented from doing.  The US can't invade a country that has nukes but because the US also has nukes, even a great power like China or Russia can't reasonably expect to prevent the US from invading Iraq for example short of their willingness to threaten nuclear war over the matter.  

As for what happens when hegemons decline, there are a variety of possibilities.  When Rome collapsed, there was no great shout of freedom.  Instead there was widespread suffering followed by hundreds of years ignorance, poverty, war and disease.  Indeed, the Roman empire, for all its flaws, was almost certainly preferable to the petty tyrannies that rose from its ashes.  The world would be far worse off if a hypothetical American decline took the form of the Roman collapse.  

The decline of the British and French Empires of the 19th century provide another example.  The British Empire in particular didn't so much collapse as fade away.  For hundreds of years after the fall of the western Roman Empire, the city of Rome decayed and was little more than a ruin with a big church and village built in its midsts. But for Britain and France the loss of their empires led to a relative brief and moderate decline in prosperity lasting no more than a couple of decades.  British hegemony was replaced by American hegemony with little loss to Britain.  

Why did the British lose their empire without losing their shirts (or houses)?  A big part of the answer is that the US governments pursued very similar policies to the British.  Trade and freedom of the sea lanes along with the expansion of stability and the rule of law were priorities of the British governments at the turn of the 20th century just as they are of the US governments at the turn of the 21st.  A big reason for that is that the rise of American power was in large part due to its taking advantage of the global system set up by the British (and to some extent the French).  

So assuming the US is in decline (an assumption with which I do not necessarily agree), there still remains the question of how it will lose its position?  Will it lose its position like Rome did - with an ugly collapse followed by global despair?  Or will it pass the torch to a like-minded rising power that owes its improving position to same global system that American power sustained?  

Anyway, I think these are interesting questions.  I'd especially like to hear from our old friend Dr. Von Brawn about this - come on, Dude, I know you're check in from time to time.  Chime in.