1. The U.S. needs restrictions on immigration in order to protect American wages.
2. Restrictions are necessary to protect the American taxpayer from abuse of the welfare state by immigrants.
After listening to the podcast, read the comments. Caplan did not convince most of those who took the time to respond to his arguments. As an economist, I found his arguments persuasive.
3. Restrictions to protect American culture including but not limited to the use of English.
4. Immigrants who do not understand our political system are going to damage our relatively free and prosperous economy by turning the United States into the kind of country they fled.
5. The increase in population in congested areas would harm naturally born citizens.
6. Immigration increases crime.