For several years, Mike and economist Nouriel Roubini have had a friendly debate about the direction of global markets. Roubini, sometimes called "Dr. Doom," has taken a pessimistic viewpoint, arguing that European financial troubles, the evolving political crises in the Middle East and a potential hard landing for the Chinese economy portend slow growth. Conversely, Mike has taken a more-optimistic tact, suggesting that expanding access to capital and demographic changes will drive growth. Above at the 2012 Global Conference, Mike makes a point by handing Roubini a Euro coin. Watch the entire discussion.