Okay. My basic point in the other thread was
1. The odd dynamic of Jus Soli being an entirely Western Hemisphere standard and Jus Sanguinis being an entirely Eastern Hemisphere standard with only a tiny fraction of one off exceptions.
Not exactly arbitrary. Most of the Western Hemisphere's population descends from people who came from the eastern hemisphere in the last few hundred years, given that and the continuing stream of immigration, it makes sense that policies would be different.
As a side note, Jus Sanguinis is not the entirety of the policy in the rest of the world. 24 countries including the UK, Germany and France, some of those we like to look to, have a modified Jus Soli:
https://en.wikipedia.org/wiki/Jus_soli#Lex_soli
2. Yes, fine I was little snarky with the whole "Glorious Countries of Europe" thing, but I still stand by the point I was trying to make with it. We're constantly being told in American how policies we don't have (Stricter gun control, Universal health care) can work because they work in European Country So & So.
Referencing those countries is valid to counter claims that things like single payer coverage are not possible, or that gun restrictions would leave us all massacred by gun toting criminals.
Faced with those examples, opponents of gun restrictions or health reform would need to argue that those countries' outcomes are not acceptable or that the US has conditions that would lead to different outcomes.
We can do the same thing with these policies. Again, I'm not intimately familiar with the full effects of citizenship policy in every country. But I do know that in many of those countries a major concern is the lack of integration of foreign born populations. I don't think denying citizenship by birth helps people integrate and feel a part of the country.
We can also look at countries like Japan which also don't provide birth citizenship. They've got an aging population and really need the new blood that a more open policy might give them.
But all of this puts us in the realm of justifying the status quo. As I started with, I think it's change which requires justification. And "Others do it that way" falls short.
3. The idea that the simple concept of the act of giving birth grants citizenship isn't a factor in how people decide to come into this country is... laughable. Yes, yes I know Republicans spend too much time scare mongering about anchor babies and Birth Tourism but that one side being unreasonable obsessed with something doesn't mean it's not a legit thing to talk about.
I think that's a valid criticism of current policy. And it is a legit thing to talk about. A reasonable case for changing policy would include some real numbers and a real projected change in immigration with a positive outcome that far outweighs negative consequences. I'd be interested to read such a case.
