Zenpundit has a great post continuing the grand strategy debate. I'd in particular like to blockquote these parts:
"In considering grand strategy, historically, except for the Romans during their golden age, state actors, even vast empires like the Soviet Union or Great Britain, never approximated a closed system that could operate without reference to rivals who could potentially present an existential threat, singly or in combination. While the Pax Romana represents the rare outcome of a successful grand strategy, most great powers wrestled with imposing their will on both their rivals - but also on the geopolitical environment or “system” in which they operated.
What do I mean by the “system”? The explicit and implicit cultural and diplomatic rule-sets; the ”rules of the game” by which powers interacted; the geoeconomic structures and patterns that were larger than any particular political entity and imposed constraints upon them, even the chance-based variables of natural resources and technological level which had a determining effect upon formulation of policy and strategy. The relationship between the architect of a grand strategy, his rivals and the world in which all were forced to operate consisted of a multiple variable feedback loop, not a diktat with a binary set of possible results."
In the context of the United States, this can be viewed one of two ways. One interpretation, which is increasingly popular, is that the US introduction into the international system in World War II set it on a path that corrupted it far beyond its original "innocence" and grand strategy that mirrored dominance of the continent of North America with offshore balancing elsewhere. The problem with this interpretation is that it does not fit the historical record. In his chapter in The Making of Strategy, Eliot Cohen points out that the US's grand strategy in the early 20th century was far from a classical offshore element. And Robert Kagan's recent study of US foreign policy, Dangerous Nation shows something quite at odds with the "innocence" interpretation.
But we should also turn this on its head. So what if the US has been changed by its experiences in World War II and the Cold War? World affairs, technology, and geopolitics hardly remain static. Just because a certain grand strategy was valid for a hundred years does not mean that was a religious document and deviation from it is an original sin for which we should bear penitence.
A second way to way co-evolution is the way that Zenpundit sets out. We are changed by our friends, adversaries, and the greater world-system that we inhabit just as we seek to influence it. That does not mean that there isn't something essential about our own nation and its culture(s) that we ought to preserve, but that such qualities are much more fluid than they often appear in books like these.