By Dan Weil Harvard economist Larry Summers and others see a strong chance of an economic downturn in the next two years. The smell of recession is in the air. Some economists have argued for months that an economic downturn may well be coming soon. Harvard economist Lawrence Summers has noted that at no time in the past 65 years has inflation stood above 4%, unemployment stood below 5%, and the economy failed to enter recession within the next two years. The first two of those landmarks have certainly been met, with inflation soaring to 8.6% for the 12 months through May, and unemployment sta…