We already have 5 million of them. Can you imagine what legalizing ALL of them means ?
Let's turn that around: what does it mean for a country to have 5 million people living in it with no legal rights, no legal protection and who are basically at the mercy of organised crime? Is that any less disruptive to that society than making them all legal?
How many more will they come ?
Probably a lot, especially if only a single country would dare to do it. Unfortunately countries are constantly competing to make their immigration laws tougher, which just results in making it harder on other countries. Somehow the solution must ultimately lie in open borders around the globe, which I readily admit won't happen very soon.
Once more, do you know of any country that legalizes ALL immigrants, or do you propose a new system of your own ?
A system of my own. A super-Schengen. A worldwide free flow of people and goods. Pretty much Utopia right now, but it might become an inevitable result of globalisation. I will readily admit that it isn't an option right now, and no country can start it on its own. But I do believe that keeping immigration restricted causes more problems than it solves, so one day the world will need to get rid of those restrictions.
Do you realize that we don't have the infrastructure for this ? Do you have any idea what happens in a school of 1000 kids when you put in there 1000 more ? Do you want me to speak about the hospitals ?
No country has the infrastructure for it, but what doesn't exist can be built. And with a little bit of luck, globalisation will make many parts of the world richer, so people don't have to move around so much for economic reasons.
If you don't like the "my house" example, then think about another house that I have and nobody lives in. Is someone justified to take it because he has no house of his own ?
This may surprise you, but under Dutch squatting law, people are allowed to this if the building is unused by the owner for quite some time. But this is an ownership issue and not significant for the issue of immigration.
With immigration, your country just gets more inhabitants. That's all there is to it. I see no significant difference between immigrants entering a country and newborns being born in it. In both cases there is an increase in the number of people benefitting and contributing to society. I see no reason for state controlled population control whether of newborns or immigrants. Most countries in Europe have (despite low birthrates) still have an influx of immigrants that is insignificant compared to the increase of newborns anyway.