I think advocacy for a tight immigration policy can be motivated by racism, but it’s not necessarily so. Therefore, I don’t think it needs to be brought into immigration debate on either side.
You’ve stated that:
Now, BrainGlutton seemd to take this as referring just to Latin American immigrants:
This lead you into the discussion of civilizations.
I’d like to return to your point from above. Assuming you’re speaking of immigration from the world at large, not just Mexico, I think you may have a point. Being an American is really about a set of values, enshrined in our Constitution: liberty, equality, rule of law, limited government, democracy, and so forth.
Much of the rest of the world does not share these values. New immigrants tend to acquire them, or at least their children do. It’s not absurd to suggest that there’s a “carrying capacity” at work, that the percentage of immigrants over a certain time needs to be below some threshold to maintain that transmission of American values. As an analogy, note that a one-state solution to the Israeli-Palestinian conflict is often rejected on the grounds that the Palestinians would hold a majority in the new single state, and could transform it so as to make it hostile to the Jewish minority.
Whatever that threshold might be, it’s much less than we take it at present. But if that was indeed your point, I think it merits discussion.