Steyn is an arch "Euro-pessimist," who backs his pessimism with numbers.

Europeans are reproducing below the "replacement rate" -- thus the average age of their populations is increasing sharply. If current trends continue, by 2050 one in three Germans and Italians will be over 65 years old. In the United States, only one in five will be so gray.

As a result, the Europe of the European Union (Steyn disdainfully calls it "Eutopia") faces economic decline and risks systemic change. Steyn writes: "Tax revenues that support the ever growing numbers of the elderly and retired have to be paid by equally growing numbers of the young and working. The design flaw of the radically secularist Eutopia is that it depend on a religious-society birth rate."

Japan faces the same "gray threat." Even China has a birthrate below the demographic replacement rate. Among the modern industrial nations, only the United States (and possibly India) has the knack for reproduction.

The United States also grows through immigration that includes political and cultural integration.

Europe's Muslims, however, are multiplying -- but they are not integrating culturally. Steyn argues that if European nations fail to culturally integrate Muslims, Europe faces profound political changes.

"As fertility dries up," he writes, "so do societies. Demography is the most obvious symptom of civilizational exhaustion, and the clearest indicator of where we're headed."

Islam cannot enjoy "political sovereignty" in Europe. Steyn adds: "Those lefties who bemoan what America is doing to provoke 'the Muslim world' would go bananas if any Western politician started referring to 'the Christian world.' When such sensitive guardians of the separation of church and state endorse the first formulation but not the second, they implicitly accept that Islam has a political sovereignty, too."

America remains an exception among democracies, Steyn concludes. America's population climbs at a healthy rate, and America politically and culturally integrates immigrants.

At least part of America remains an exception. "Demographic trends," Steyn observes, cheekily, "suggest that the blue state ought to apply for honorary membership in the EU; in the 2004 election, the Bush-voting states had fertility rates 12 percent higher than Kerry-voting states. Barring a sudden change in electoral fortunes, Democrats are going to be even more depressed at their 2010 and 2020 reapportionments."