Carlo Salerno, an education economist and a vice president for research with CampusLogic, writes: New ideas are warranted, and sometimes we miss the simple ones hiding right under our noses. Risk sharing is inevitable, and Congress can use the opportunity to radically alter the way American higher education does business. How? By just requiring colleges and universities that participate in the federal government’s Title IV aid program to cosign the student loans that they expect their students to take out.