To judge from John Gardner's 10th novel [Mickelsson's Ghosts], published shortly before his death last month in a motorcycle accident at age 49, he believed in ghosts. Also in witches, hex signs and divergent spectral assemblies, such as a government-supported group of Mafia landfillers and a Mormon-affiliated SS troop called the Sons of Dan. Although Peter Mickelsson, Gardner's primary witness to these questionable incarnations, is a philosophy instructor who might well be cast as �...