The latest craze in the Republican presidential race is abolishing birthright citizenship, in which anyone who is born in the United States is automatically made a citizen. This is a position that has long been a favorite of the party's nativist wing, but was placed front and center when Donald Trump advocated for it in an immigration white paper. Scott Walker agreed, and even Jeb Bush only lamely argued that it would be tactically difficult to enact. Even Bobby Jindal came out against it — only "for illegal immigrants," but it's still a pretty shocking position given that, as the son of legal immigrants, birthright citizenship is the only reason he is a U.S. citizen in the first place.
This makes a notable contrast with the typical way that conservatives approach constitutional jurisprudence. Birthright citizenship is in the Constitution, which is usually presented as a quasi-holy writ (if not actually the work of Jesus Christ himself). It is a text that must be interpreted as originally intended by those who wrote it. There can be no adapting this weird and antiquated text to new circumstances, even if large portions of it were written by 18th-century slaveowners.
It's doubly strange that conservatives would attack the Fourteenth Amendment, which contains the birthright citizenship provision. It's both a source of genuine American exceptionalism — and thus a key distinguishing characteristic between the U.S. and the nations of Europe — and one of the Reconstruction Amendments, which dramatically improved the Constitution. What gives?
Honestly, before those amendments, the Constitution flat-out stank. One might argue that it was a minor improvement over Britain's constitutional monarchy, which had been developing an increasingly democratic character since the Glorious Revolution of 1688. But on the other hand, presidential democracies are clearly inferior in quality to parliamentary ones. The whole idea of a federation of states is often foolish and sometimes grotesquely unfair. The Electoral College is to this day an embarrassing joke of a process.
But more to the point, before 1865 the Constitution implicitly condoned slavery, and excluded all blacks from citizenship. The Reconstruction Amendments changed it from a document that organized one of the most brutal tyrannies in all of history — the antebellum South — to one that recognized the inherent humanity of all its citizens, in theory at least. The Fourteenth Amendment, by firmly preventing any stripping of citizenship rights from the freed slaves, was key to that process, as was the Thirteenth Amendment banning slavery and the Fifteenth Amendment barring racial discrimination in voting rights.
As historian Eric Foner writes, birthright citizenship really does mark out one area where America is quite different from most of its peers. Among industrialized nations, only Canada and the U.S. still have it. Indeed, with Europe's long history of violent conflict, racial and religious sectarianism, and the subjugation of colonial peoples, being stingy jerks with citizenship status is almost a signature European characteristic.
So if you were dedicated to traditional conservative fetish-worship of the Constitution and suspicion of Old World habits (remember Freedom Fries?), and you also bowed to the universal belief that slavery and Jim Crow were terrible, then it stands to reason that you would think the Fourteenth Amendment was pretty good. If you were concerned with immigration, you might respond that the text is outdated and should be changed — but that's poles apart from the typical conservative view of the Constitution. Indeed, this is how a liberal would go about arguing for the implementation of, say, the Equal Rights Amendment.
If I didn't know any better, it'd be pretty easy to believe that xenophobia is behind the desire to repeal the Fourteenth Amendment, and that "originalism" is merely a veneer of historical legitimacy applied to ordinary political opinions that are basically unconcerned with the content of the Constitution. But that can't be it.