Michael Mandelbaum's "The Ideas that Conquered the World" (2002) showed how
the fundamental USA principles of democracy and free market have come to
be considered by everybody (even most of the USA's enemies) as cornerstones
of the human civilization. Even dictators now claim to hold democratic
Michael Mandelbaum's new theory is that a) the USA is de facto the government of the world, and b) this is good for the world, regardless of the fact that sometimes the USA may make the wrong decision.
The second point is easier to defend. Wars in western Europe ended in 1945 after at least 15 centuries of continuous warfare. It can't be a coincidence. Ditto for the Far East, where Japan has become the most peaceful country in the world. Furthermore, countless international crises have been defused thanks to the fact that the USA took one side of the crisis (not necessarily the right one, but the fact that the superpower was supporting one side of the crisis helped avoid a full-fledged war). Basically, having a police officer is better than not having one, as long as the police officer behaves a bit better than the criminals, and even if the police officer is not perfect.
The first point, instead, is debatable at best. The USA is too absent minded and detached to be considered a world government. Not only are there too many countries (even close allies like Germany) that openly disagree with the USA and get away with it, but there are also countless occasions in which the USA simply refuses to rule the world. Actually, the USA has exhibited a pattern over the last 50 years of trying to stay away from crises and withdrawing as son as possible, a behavior that is the exact opposite of the behavior of most empires of the past.
Economically, the USA controls the world as much as the world controls the USA. The USA is a powerful machine to create business around the world, but it then depends on precisely the business that it has created. There are countless lobbies in the USA that are run by foreigners and funded by foreign entities. The USA is far less monolithic than its critics claim: the USA often behaves like a loose aggregate of capitalists, not like one monolithic imperial power. These and other factors make it difficult to claim that the USA is the world's government.