It's obvious we need more scientists and skilled engineers. What we're getting instead are waves of poor people with a high school education or less. They're nice people; nobody doubts that. But as an economic matter, this is insane. It's indefensible, so nobody tries to defend it. It's indefensible, so no one even tries to defend it.Instead, our leaders demand you shut up and accept it. We've got a moral obligation to admit the world's poor, they tell us, even if it makes our own country poorer, dirtier and more divided.