This interview with First Things’s R.R. Reno contains something worth thinking about:

R.R. Reno: We have to have a welcoming, pro-immigration society that is capable of maintaining social unity. I would argue that you can’t have multi-cultural democracy—there are no multi-cultural democracies. They’re all in states of civil war or parts of empires.

Green: Well, but the United States is a multi-cultural democracy.

Reno: No, it’s not. It’s very homogeneous. When foreigners come to the United States, they’re always shocked by how homogeneous we are. We just do a very good job of assimilating people and making them into Americans.

Green: So if by “multi-cultural” you don’t mean a diversity of religions, a diversity of ethnic backgrounds, a diversity of national origins, and a diversity of individual political ideologies—all of which the U.S. has—what do you mean?

Reno: Shared heritage, common identity. When you’re traveling abroad and you meet another American, it doesn’t matter if they’re Asian, African American, or whatever—you hang out with them, because you have shared habits of mind and sensibilities.

Green: So you’re pointing to a cohesive sense of national identity.

A culture is a holistic, comprehensive force that binds a people (a diverse people) together. I think it’s telling that the interviewer considers “multiculturalism” and “diversity” to be interchangeable.