The right calls it a crisis. The left insists it isn't. After Fed Chief Alan Greenspan waded into the Social Security debate, a Senator called him a political hack. Unusually harsh words for a Fed Chairman. Today, Mr. Greenspan was back on the Hill and back in the fray. But at a Senate hearing, he offered a suggestion to remove some of the bitterness. As our own John Dimsdale reports, it's an approach Mr. Greenspan has some personal experience with.