A great post titled "Terrorism and the Assumptions of Classical Liberalism" from Randall Parker on whether we've stretched the bounds of liberalism to the breaking point.   The classical liberal assumes that everyone values their own lives at some generally equivalent level.   Hence the Ring 0 / Root of order is the reciprocal threat of loss of life if you violate the social contract.   However, terrorist tactics -- particularly suicidal ones -- directly target this conceit.

Too many modern liberals (and I include leftist liberals, libertarian liberals and even some neoconservative liberals) have so internalized the need for everyone to accept the existence of everyone else that they have a hard time accepting the consequences of the idea that others do not share their beliefs.

...The problem for classical liberalism today is that technological advances are making it easier to create conditions in Western societies that are outside the range of allowable conditions needed for a liberal society to survive.

This is normally an inflammatory topic (it very quickly leads to questions about what is Americanism?  how we can enforce it? what types of immigration can/should be allowed? etc.) but Parker does a good job of coolly rationalizing and explaining his point of view.