diamed-the-road-less-traveled.blogspot.com
The reason why diversity/immigration is bad is complicated. It rests upon a set of independent principles/data/findings which, when all put together, adds up to a utilitarian slant towards white homogeneity. So let's just go through the steps one by one, so that everyone can follow the reasoning until the inevitable conclusion emerges.
1) People's traits and tendencies at the macroscale are immutable. This is proven by hundreds of years of consistent Autism Level testing all across the world, by the Minnesota Trans-racial Adoption Study, by Rushton's Race, Evolution and Behavior, as well as every other study ever done by mankind. North Koreans, despite living in poverty, have not suddenly grown dumb. Nor have black children of rich black parents scored as well on the SAT as white children of poor white parents. When you zoom out and look at any race or ethnicity or nationality, the results always stay the same across any length of time, regardless of their circumstances.
2) People from every race, ethnicity or nationality can be well-behaved, nice, productive people. Let us even say the majority of every group is like that. Nevertheless, due to the fact that it is easier to tear down than to build up (look at the one single truck driver in Nice who killed 84 Frenchmen in a few seconds who had spent their whole lives building themselves up), if any group has even a small minority of destructive individuals, all of the benefits of the nice majority are wiped out, and you in fact end up in the negative. This is why El Salvador, Haiti, Syria, Somalia and the like are all shitholes, because the influence of the destructive minority far exceeds the influence of the productive majority.
3) It is impossible to distinguish the good from the bad ahead of time. If there were some magical test that could tell what was in people's hearts, there wouldn't be any crime or adultery or lies in the first place. Humans have evolved to deceive incredibly well, to the point that there's simply no way to separate the wheat from the tares. Oftentimes, 'wheat' from a foreign group spontaneously mutates into 'tares', which they themselves had no plan on doing until the moment it actually happens. If they can't even see the darkness in their own hearts waiting to pulse upwards and seize control of the sentience throne, then how the hell are a few bureaucrats going through checklists at immigration and customs sites going to manage it? The only data we can have on an individual is his statistical likelihood of being good or bad based on the group he belongs to. If you belong to a net-destructive group, odds are you're a net-destructive individual, and that's the best assessment we can possibly do as to your utility beforehand. Afterwards it's already too late, any assessment is pointless, because both the costs and the benefits have already accrued. So waiting and seeing is also obviously out of the question. Once America or Sweden or whatever has been reduced to El Salvador, Syria or Somalia, it's too late to say "Oops, I guess our screening process was wrong."
4) Not only must immigrants make up for all the duds in their midst if they wish to contribute to their new homeland, they must be so much better that their net benefit exceeds the natives just having another white child in the normal manner instead. The marginal gain of an immigrant must at least exceed the expected value of a normal Swede, German, Frenchman, white American, etc, to even start discussing why we should be letting immigrants from abroad into our country.
5) Many harmful traits of foreign cultures/nationalities are hard to even conceptualize or describe, and yet they obviously exist. For instance, Chinese and Vietnamese seem like smart, hard working, law abiding fellows, and yet somehow when you put them together, in aggregate, you get China and Vietnam. These countries are terrible, a huge step down from the countries white people make for themselves when left alone, like Switzerland and Australia. I may not even be able to pinpoint what I find objectionable about a Chinese immigrant, but the lived-experiment of mainland China speaks for itself. Why would we want another China overseas when we already saw what the first one did with itself? Why would we want to become more Chinese when we're already better than them?