By "Open Borders" means the right of people to live, work, & study in any country in the world. Makes the economic & moral case for the end of restricted immigration rule regimes. I've been convinced of their point for a long time now, but I like how this book took on pretty much every argument against open borders. I did wish Caplan dealt more critically with the idea that the entire population of the earth moving to the United States would almost double the global economy (for instance, would there be enough water for everyone?), to give some idea if this scenario has a basis in reality, or if they just calculated how much more everyone in the world would be paid if they worked in the U.S. There is also no environmental discussion. It felt weird to read a case for unrestricted immigration while skirting the issues of climate crisis & climate refugees, or to read about a potential doubling of global economic output without any discussion of environmental constraints. The end notes were often interesting (such as in the trust level discussion; "...slavery persistently damaged trust in Africa..."), so don't skip them!