This past St. Patrick’s Day, TV viewers were treated to a strange sight on The Colbert Report, Comedy Central’s late night satire show.

Host Stephen Colbert, who never misses an opportunity to remind viewers of his Irish roots, was interviewing a very professorial African American woman. Or at least she appeared to be African American.

But when Colbert noted, with mock seriousness, that he doesn’t “see race,” he asked her if she was, indeed, African American.

“I don’t know,” Colbert’s guest said. “I have a Ph.D. Am I white?”

From there the interview got even stranger. Colbert ranted and raved about Cromwell and Northern Ireland and how the Scotch-Irish “do not have one ounce of Irish blood.”

In the end, Colbert and his guest arm wrestled.

The reason for all of this silly banter was that Colbert’s guest, Princeton professor Nell Irvin Painter, has written a new book called The History of White

People. An important portion of the book explores the painful process of Irish assimilation into the American mainstream in the wake of the Irish Famine.

"What really surprised me at first was the level of hatred that people I thought of as white directed at other people I thought of as white," Painter said in a recently published interview.

"So the amount of hatred directed toward the Irish immigrants in the middle of the 19th century, I -- coming out of straight U.S. history -- I thought of those Irish people as people who beat up other people.

“That's a dumb way of saying it, but that's how poor Irish people figure into the general history of the U.S."

Give Painter credit for her honesty. The basic argument she is making is that race is basically a fake category. Religion is a choice you make based on faith or birth.

Ethnicity generally refers to the nation you hail from. But race?

Well, sure, by now we believe it is based on skin color. But that, Painter argues, is superficial.

In fact, the Irish and their famously white skin were, for a very long time, not allowed to enter the exclusive white club in America.

Blacks, of course, were lowest on the racial ladder. Then Jews, Italians and Slavs began coming over in larger numbers and they faced their own discrimination.

Painter’s book could very well have been called “How the Irish Became White.”

There’s just one problem with that. A book with that exact title was published well over a decade ago.

It begs the question -- who knew the Irish were still “thought of as white”?

Okay, so I’m dabbling in some Colbert-level absurdity here myself. Painter’s book is much broader in scope than How the Irish Became White by Noel Ignatiev.

Painter’s book goes all the way back to the Greeks. And sure, as Painter and others argue, if you think about it, race is kind of a hard thing to define, especially in a place such as America, where all kinds of different people intermarry.

And yet, something is missing here. Painter, like Noel Ignatiev before her, acknowledges that the Irish initially had a horrible time in America.

But you get the sense that once they were finally allowed into the country club, they didn’t just become white. That’s all they became.

Irish American novelist Peter Quinn dealt with these issues admirably in a 1996 essay entitled “How the Irish Stayed Irish.”

If the Irish essentially became cozy WASPS as the 19th century wore on, how on Earth can you explain this group’s century-long obsession with liberating the nation they left behind?

How do you explain their construction of what amounts to a separate Irish Catholic nation in America, where you grow up in vast cities such as New York or Boston, and yet, from the cradle to the grave, define yourself mainly by the people and particularities of your parish.

Then again, Painter’s index for The History of White People shows she read Ignatiev’s book, but not Quinn’s essay.

Oh well. At least it’s a partial history.

(Tom Deignan will be discussing “20 Books Every Irish American Should Read” at the mid-Manhattan branch library, 455 Fifth Avenue, April 17 at 2:30 p.m., and at the Riverdale, Bronx branch library on April 22 at 6 p.m. Contact or