I believe the argument was (or should have been) that immigration increases the GDP of the destination country by more than it decreases the GDP of the origin country, thereby increasing worldwide GDP per capita.
But the argument is also made that “GDP goes up” in the context of the immigration debate and nationalism. That is the usual context of the question these days.
From a nationalist perspective of the existing citizens of the country, their GDP may go down when immigrants are allowed into the country, even while the GDP of the aggregate including the new immigrants is higher than the original GDP of the existing citizens.
And of course, the influx of immigrants also affects the distribution of GDP within the existing citizens.
I believe the argument was (or should have been) that immigration increases the GDP of the destination country by more than it decreases the GDP of the origin country, thereby increasing worldwide GDP per capita.
That should be the argument.
But the argument is also made that “GDP goes up” in the context of the immigration debate and nationalism. That is the usual context of the question these days.
From a nationalist perspective of the existing citizens of the country, their GDP may go down when immigrants are allowed into the country, even while the GDP of the aggregate including the new immigrants is higher than the original GDP of the existing citizens.
And of course, the influx of immigrants also affects the distribution of GDP within the existing citizens.