Economists attempting to dissect the U.S. labor market in recent years have been perplexed by the number of people leaving the labor force entirely. In a little over a decade, the number of people either working or actively looking for work has declined to 62.8% from 67.3%. The decline started in the year 2000 and has accelerated since the recession that began in 2007. The question for economists: will these people return if the economy strengthens?

Recently the White House Council of Economic Advisers weighed in on this debate. They argued that slightly more than half of the decline of the labor force is due to the aging of the population. And aging clearly has a role. More and more of the Baby Boomer generation, born after World War II, are reaching their late 60s and retiring.

But many economists believe the decline in labor force participation is about more than retirements. Many workers, they say, are simply giving up on the labor market in frustration because the economy has been weak for so long.