Tucked away in the pages of a new report by the U.S. General Accounting Office is a startling statistic: 40.4% of the U.S. workforce is now made up of contingent workers—that is, people who don’t have what we traditionally consider secure jobs. There is currently a lot of debate about how contingent workers should be defined. To arrive at the 40.4 %, which the workforce reached in 2010, the report counts the following types of workers as having the alternative work arrangements considered contingent. (The government did some rounding to arrive at its final number, so the numbers below add...