It is generally true that the past is the best guide to the future that we have but that is not to say that it is always a good guide. Does anybody seriously think that (say) America of 100 years ago is the same as the America of today?

Yet by far the commonest argument coming from the Left about immigration in general and about Muslim immigrants in particular is precisely that America of today IS just like the America of 100 years ago. You can read the latest such article in the NYT (by Kristof). It is an argument so hackneyed by now that he could almost have written it in his sleep. Maybe he did.

The argument is that the Irish, Italians and others who came to America in the 19th century were viewed with grave suspicion by many and suffered from discrimination but in the end blended in seamlessly with Americans of other ancestries: The melting pot.

From that Kristoff and others conclude that Muslims will eventually “melt” into a homogeneous American population also. And perhaps many will. But there are two crucial difference that will at least greatly hinder full integration:

1). In the 19th and most of the 20th century, immigrants were EXPECTED to assimilate whereas these days multiculturalism reigns and the very word “assimilate” is almost an obscenity to the Left.

2). The Italians, Irish and Poles came from CHRISTIAN backgrounds so had a considerable degree of common culture with Americans originating from earlier waves of immigration. More to the point they did not come from a culture that DESPISES Christian and post-Christian civilization, whereas Muslims do.

It is a basic imperative of Islam to attack and if possible conquer other civilizations — and they have been doing it more or less continuously ever since the conquests led by Mohammed himself. They were even attacking Christian targets at the time of America’s War of Independence and President Jefferson sent warships to combat them.

So the wave of Muslim immigrants is a wave of people whose basic teachings are hostile to America. That has never happened before and therefore makes comparisons with previous immigrant waves invalid.

The controversy over the “Ground Zero” mosque in NYC has of course brought to the fore the question of how Americans should react to Muslims in their midst. I myself, as an Australian living in the happy obscurity of a small Australian city most people have never even heard of, have no dog in that fight. I think the response to the mosque proposal is for New Yorkers and New Yorkers alone to judge. But I don’t think it is unreasonable for New Yorkers to be hostile to anything Muslim given the hostility of Islam to the West.

But Muslims are still a very small immigrant group in America and the long-standing argument about immigration to America is about Latino illegals, not Muslims. And here we see the same argument from the Left: People who arrived legally from Europe a century or so ago eventually assimilated so people who arrive illegally from Mexico (etc.) will also eventually assimilate. And no doubt many will and in fact many have already done so.

But arriving legally and arriving illegally are two very different things and Europe is also very different from Latin America. Europe is the fountainhead of modern civilization whereas Latin America is a civilizational backwater (to put it kindly). So once again there are large differences between earlier arrivals and recent ones that create considerable potential for outcomes different from what we have seen in the past.

And the omens for Hispanic illegals assimilating are not good. The children of Irish, Polish, Italian (etc.) legal immigrants became indistinguishable from other Americans but that is not so with the Hispanics. That Hispanics have a notably higher crime-rate than non-Hispanic whites is concern enough but their children are even worse, even more prone to criminality. As well as black gang-bangers America now has a proliferation of Hispanic gang bangers. Far from assimilating into the mainstream, the children of the illegals have moved even further away from it.

So once again the complexities of reality upset the simplistic theories of the Left. Neither in the case of Muslims nor in the case of Hispanic illegals can we expect the universal assimilation of the past. Permanently hostile subgroups are instead to be expected. Americans are right to be concerned about that.