Hardened Border Paradox

      1) Define pay riding. What is free riding? Over time, can the unilateral solution likely turn into a multilateral one? 2) "Is it cost effective to spend millions and millions of dollars in an effort to stop a hand-full of people" who are bound to terrorize the United States? 3) What is the "Hardened Border Paradox? What is the "Open Border Paradox? How can both be overcome?