Lawrence Auster notes that the concern voiced by some Western commentators that immigrants "are separating instead of assimilating" overlooks the real problem.
In fact the issue is not that these groups are "separating" from the mainstream culture. It is that they are expanding their numbers and power--the power of their culture, religion, or ethnos--and in the process weakening the culture, sovereignty, and nationhood of the host society. But Western opinion makers almost never state the issue in those terms, because that would mean defending the specific culture of the host society, rather than defending the liberal ideal of the mutual harmonious blending of all peoples.
Auster further notes:
The fear that Muslims (and others groups) are "separating" themselves is a mirror image of the modern liberal belief in the West's unlimited capacity to assimilate non-Western and nonwhite immigrants. It conveys the idea that such separation is a deviation from the normal, natural, and correct course of things, which is assimilation. From the liberal point of view, assimilation, which is the liberal ideal, and separation, which is the failure or rejection of that ideal, are the only two conceivable options.
As suggested above, this view of the problem excludes other possibilities, such as that the immigrant group is not interested in assimilating or in separating, but, as human groups have been doing since the beginning of time, in spreading itself at the expense of other groups, namely our group. This possibility is never admitted by mainstream commentators, as it would mean the end of the belief in the universal sameness and equality of the human race, and thus the end of modern liberalism.