Of course, if we had to raid every business and arrest every illegal, it would take forever and cost billions. That’s why an attrition policy — one that combines conventional enforcement with what I call a “firewall” approach of denying illegals access to a normal life here to persuade them, especially the more recent ones, to give up and deport themselves — is the way to go. In fact, I’ve just released a five-year cost estimate for an attrition strategy, based on the government’s own data — efforts that would cost an extra $400 million a year for five years could cut the illegal population by almost half. Think I’m wrong? Let’s try it and see.