You can't force muslims to adopt a one-child policy without the rest of society also doing so. Any segment that is forced to curtail its procreation will allege future demographic disequilibration, that cannot be perceived as either Constitutional, just or humane in any part of the world. There are three ways I can think of to correct the imbalance: 1) offer native residents, irrespective of race or religion, incentives to have more children: since the greater proportion of native European residents are non-Muslim, a marginal or significant correction of medium-run demographics, depending on the incentive, might be possible; 2) have an immigration policy that is sub rosa discriminatory against Muslims or to entrants from Muslim nations; and 3) implement a universal one-child policy for all residents. The first suggestion might be possible only in better economic conditions and the third might be considered contradictory to a democratic ethos. But the second is certainly implementable, if Sweden (and other Nordic countries) is (are) content with a dip in immigrant numbers and a slight alteration in the financial profiles of its immigrants. What usually tends to happen, is that the Muslims who migrate to Western Europe and the Nordic countries tend to be more moderate than their conservative counterparts back home and also better financially endowed, but their children, who grow up in an environment where the general ethos is liberal are torn between a culture that is liberal in the public space and one, that is relatively liberal compared to the parent country, but still vastly more conservative than the host country, at home. Those that gravitate towards extremism usually are incipiently unable to racially identify themselves with their native counterparts; and the process of increasing extremization makes them disillusioned with what they see around themselves. A familiarity-bred contempt of their rules and practices prevents them from identifying with their parents, while at the same time their inability to racially and culturally identify themselves with their peers leads them to eventually outdo their parents. These individuals will, eventually, tend to see the entire West as morally opprobrious while at the same time viewing those from among their own ethnic group that have struck a happy medium between original and adopted cultures, or those that have conformed to their external environment, as traitors. This phenomenon is particularly prevalent in Islam, since Islam itself espouses a way of life that is peremptory, obdurate and harsh.
In the US, this is preempted because of a strong national culture. The pervasive, omnipresent identity of Americanism tends to coerce second-generation immigrants into conforming with the national ethos, lest they face a social extrusion and ostracism that is much more virulent than in European society. Ironically, in order to create this dynamic, Europe will have to allow a controlled right-wing presence in European politics, just as the presence of the Shiv Sena prevents any untoward Islamic chauvinism by those that would seek to hijack the anthropocentric identity of the state, in Mumbai.
The results are unpleasant.
