HA HA Ben Carson is an IDIOT
who does not even understand what slavery was because he said that slaves were a kind of immigrant
(different than ordinary, voluntary immigrants)! He is also a racist, OBVS and...oh...uh...right...well, HE WOULD
BE if...well...you know...
OH YEAH WELL OBAMA said the exact same thing
like eleventy-million times! CHECKMATE, LIBTARDS!!!111
However...actually, that Federalist
post doesn't make the case all that clearly. In few of those quotes, taken by themselves, does Obama explicitly say what Carson said--that slaves were a kind of immigrant. The vast majority of the examples are variations on a slightly different line:
no matter whether our ancestors landed on Ellis Island or came here on a slave ship or crossed the Rio Grande, we are all connected to one another. We rise and fall together.
(In fact, like 10 of those quotes are really just the same thing said on different occasions, if that matters.) Above he doesn't say that we're all immigrants, but just that we all come from somewhere else--which is different. 'Immigrant' does, to my ear, suggest coming here voluntarily...though I'm not giving that point the attention it should get. At any rate, that's part of the problem... Dunno what the OED says...
So...this counts against the angry conservative Obama Gambit
in defense of Carson.
But...in one of the other Federalist
quotes, he does put that claim in the context of calling all the listed types of people immigrants:
We say it so often, we sometimes forget what it means — we are a nation of immigrants. Unless you are one of the first Americans, a Native American, we are all descended from folks who came from someplace else — whether they arrived on the Mayflower or on a slave ship, whether they came through Ellis Island or crossed the Rio Grande.
And, in one speech that the Federalist links to but doesn't quote, he also says
Certainly, it wasn't easy for those of African heritage who had not come here voluntarily and yet in their own way were immigrants themselves.
 Most of the Obama quotes that are offered as evidence to demonstrate liberal hypocrisy on this point don't technically prove it on their own.
 The quotes are arguably in the same spirit as Carson's statement.
And, more importantly:
 When taken together with the statements from the naturalization ceremonies, the other quotes do support the defense / charge of hypocrisy.
Even if  and  are/were wrong:
 The statements at the naturalization ceremonies alone would provide the grounds Carson's defenders need for the defense, and for evidence of liberal hypocrisy.
I think there was something else, too, but I'm in a hurry and didn't sleep...so...derp.
The righties are right, the lefties are wrong.
Carson's statement is predicated on what seems like an overly-expansive interpretation of the term 'immigrant.' It clangs off the ear, but seems to be consistent with a rather thin definition that he provides later. Besides, there are other cases in which we count people as immigrants even if they didn't come by their own free will--as in the case of small children. It's weird to call slaves immigrants, and it's kinda false, but it's hardly some capital offense.
The bigger point, however, is, to my mind:
This bullshit, mostly semantic nit-picking needs to end, and the left is, by far, the worst of the two offenders with respect to that kind of nonsense. Carson said something odd while kind of stretching to make a point. One might point out that it's odd, or ask him whether he thinks that slaves were, strictly speaking, immigrants, or paradigmatically immigrants, or whatever. But this freakout over what is largely a semantic infelicity that obviously doesn't underlie anything like a substantive misunderstanding is just idiotic. Nobody, anywhere, can seriously believe that Carson is unaware of the difference between slaves and (most other?) immigrants.
Also, note that no reasonable defense of Carson would have worked here, short of an inconsistency/hypocrisy defense leveraging statements from an unimpeachable lefty--e.g. Obama. And the defense probably would not have worked if it had tried to leverage the words of a white lefty--because you know what the internet left's rebuttal would have been like in that case...
So, if Obama hadn't happened to have said something identical, there'd be no way to block this dumb, overblown criticism.
Ok, this is all extremely stupid, and I can't believe I just wasted that much time on it.