One of the ways in which the Athens of Pericles is a terrible model for how to manage a just society is the ultra-restrictive citizenship law he introduced in 451, reserving full legal and political status only for those whose parents were both Athenians. At least in part because of a shortage of sources, the context and purpose of this law is much disputed; Aristotle’s suggestion (Politics 1278a) seems as plausible as any, that this is a means of restricting the numbers of citizens in a polis that is expanding, presumably in order not to spread the benefits of citizenship (and, in Athens, of empire) too widely. In other circumstances, the benefits of immigrants are widely recognised; we can see this in Xenophon’s proposals in the Poroi for revitalising the Athenian economy by attracting more foreign traders and other entrepreneurs – though without actually opening up citizenship – and still more in Thucydides’ account of the way early Athens grew through offering a safe haven to refugees from other parts of Greece: “by becoming citizens from the very earliest times they so increased the city’s population that Attica could not contain them and the Athenians later sent out colonies to occupy Ionia as well” (1.2.6). Immigrants as an asset – but sometimes a state decides that it wants all the benefits of their contributions without offering anything much in return, however long they’ve lived there and however much they’ve done for their adopted home…
Even the Japanese are realizing they need to be less of a hard ass about immigration. They’ve been expanding their work VISA programs all year to be more generous and protective of the immigrants.