Mr. Harbison,I do think that Buffet's increase in wetlah affects your productivity, and thus your mobility. The farther ahead he gets, the less believable it is for the lowest classes to believe they can be him. When the gap is narrow, aspiring to be "the rich" is sensible and realistic. Everyone works hard because they believe they can climb the economic ladder. When the gap becomes so great you have better odds of becoming "the rich" by playing the lottery, more and more people give up the hope and start settling for less, which means a decrease in productivity. I'm not saying it's right, but it's how psychology works...at least in the argument that an income gap reduces mobility. A comparison everyone posting on a climate science blog can probably see in their own lives is that we don't aspire to run in the Olympics. We all probably gave that dream up long ago when reality informed us that no amount of hard work was going to get us there. Economics operate the same way.I think Americans have ignored the statistics of social mobility for a long time, preferring to indoctrinate themselves and their children into a dream involving bootstraps, ingenuity, and hard work. Indoctrinate is a scary term, but I think it's the best one to describe the approach we take to the work ethic virtue. We had lots of work ethic messages targeted at children when I was in school. I also don't think it's too out-there to say that most parents believe it's their job to instill a strong work ethic. If parent's take it as their mission, the message is in school, and suggestions otherwise are basically heresy, you have strong case for indoctrination, for better or worse. At the risk of stating the obvious, a strong work ethic is not necessarily a feature of culture and education in most of the world's countries. The American Dream is basically a work ethic wrapped in hope. Real stats about the income gap tear the insulating hope part away, exposing the work ethic part to the elements. Whether it wears away or stays solid largely depends on how high up the economic ladder you are. As the gap widens the rich will maintain a belief that their position is substantially due to their work ethics, and poor people will increasingly believe theirs is not.