Migration obviously happens whether we "like" it or not--if not, humans wouldn't be spread out all over the earth. People moving around is the original migration, happening first hundreds of thousands of years ago. Only in the last few hundred years has the idea that it can and should be limited come to be. (Even in the first hundred years or so of US history, there were virtually no efforts to "control" migration in any meaningful way, until the Chinese Exclusion Act of 1882).
So while people moving around is much older than the contemporary state system, it is often seen as a threat to it; one that they try to, if not stop, at least control from time to time.
Let's kick off this discussion with a consideration of what the benefits and drawbacks of migration, especially from poor countries to rich ones, actually are. Based on the readings, what are the biggest advantages and drawbacks? Which are greater, from the perspective of overall human development, in your view?
Reading materials:
Snarr and Snarr, Khalid Koser, International Migration: A Very Short Introduction, ch. 3 ("Migration and Globalization" and ch. 4 ("Migration and Development")