Is Income Inequality a Threat to the Middle Class?

One hundred years ago, in the era of Robber Barons, the richest 1% of Americans had 18% of the nation's income. The income tax, labor unions and the New Deal leveled things out but, since the 1970's, the income gap has been growing again and now it's wider than ever. Are the very rich just the top of a healthy middle class, or is the economy a zero-sum game with top earners refusing to let their wealth trickle down? We hear a debate that underlies the issues being raised in this year's midterm campaigns.