Q95. "Why has the Constitution endured the last two hundred years when many other countries' don't?"
A. There are lots of reasons, not the least of which being that the Constitution established a government that has served the people well and has protected the rights of the people. If either of these two goals had not been met, the Constitution we have today would have been replaced a long time ago.
Now, obviously, our government has a lot of room for improvement, and there are lots of issues that we face, such as Presidential power and campaign finances. And the rights of the people are not absolute, in law or in practice. Over time, many changes have been suggested, though in the end, few actual changes in the Constitution have become amendments. But when you look at the revolutions in nations since our own, it is clear that the people of America have led a relatively quiet existence with a relatively benign government. There have been times of unrest, to be sure, such as the Civil War, Reconstruction, the Depression, the Red Scares, Desegregation, etc., But even so, there has been no reason to drastically change the Constitution.
The brothers Collier, in Decision in Philadelphia (available on my Books Page) say the following are the reasons the Constitution has survived: it reflects the ideals of the American spirit; it recognizes human nature; it establishes a strong government; the rights of minorities are protected; and finally, it is not reflective of any particularly radical ideal or viewpoint, but rather a melding of many opinions and philosophies.