But there is no overpopulation in Europe in terms of land availability or food supply (Europe's population density is 72 person/sqkm, the last famine was during WWII and not even then widespread). Sure, population density is very high in urban centers but there is still plenty of space in the country side. It just needs more incentives to be settled. So 'importing new people' really isn't a problem.
I cannot find any information on 'Replacement breeding in the emigrant nation' so I really cannot say anything about the validity of this statement. Could you provide a source?
EDIT: Fixed sqm to sqkm. Elaborated second paragraph.
Overpopulation is in the eye of the beholder. 72 is enough, we don't NEED more people! Side effect of overpopulation capitalism: need more people on the same space ? You need apartment, which requires capital, which means America and there 1%/90% ratio ... Do not want!
Are you suggesting that Europe is not capitalist already? I think it is and despite this we have still managed to maintain greater equality (as measured by Gini coefficients after taxes and transfers) than the United States by having more state intervention. Why would immigration change that?
I'm not saying that immigration is just going to turn out to be a positive effect without any action. Measures have to be taken to account for it, but I think investing large amounts of money in trying to prevent it is the wrong approach, because it a) does not work b) is inhumane, and c) does not solve the actual problem (people being forced to migrate).
You said that both things ('importing new people and replacement breeding') contribute to overpopulation. Importing new people can only contribute to overpopulation if you consider it locally. If you consider it globally moving X people from A to B cannot possibly directly affect the total amount of people in A and B. I considered overpopulation only in Europe and not globally because neither did you.
You're not understanding. Overpopulation involves the worldwide figure. The point of the statement is that immigration increases overpopulation by moving people to a new place, and then replacing them in the original place.
http://www.theguardian.com/world/2013/nov/01/razor-wire-divi...
http://www.spiegel.de/international/europe/asylum-policy-and...