Taken together, they provide much more material to digest as we think about how robust the "cultural" basis of a pluralistic society has to be. Dutch multiculturalism, for example, used to be based on "shared and nonnegotiable understandings of three things: language, history, and law." Radical Islam rejects all three. And in Rotterdam, for example, Muslim immigrants constitute nearly half the population and more than 60% of the school-age popupulation. My dads old neighborhood, in Rijswijk, a suburb of the Hague, has become a Muslim enclave, essentially foreign to someone who lived there for 20 years and visited for another 20.