I'm not normally a fan of Krugman but I give him props for pulling Khaldun out. The entire passage beginning with: > "This implies that the new rulers are at

I'm not normally a fan of Krugman but I give him props for pulling Khaldun out. The entire passage beginning with: > "This implies that the new rulers are at first considered “barbarians” by comparison to the old ones..." was also expounded upon at length by Toynbee in "A Study of History". The 'creative minority' that is the heart and soul of most economic/political efforts (such as building out of the American industrial base in the 19th-20th centuries) later becomes the 'dominant minority' that is more interested in holding the power given to them by previous generations rather than building out the company/corporation/empire. As the dominant minority lose their grip and their power, a new generation of 'barbarians' or outsiders (as viewed by the decaying powerbase) fills the vacuum left by the old elites. It's a dynamic we see time and again in smaller and larger spheres of human activity.