The Washington Post recently published a harshly anti-Bush op-ed by Douglas Brinkley, who does not bother disclosing his John Kerry connections. Shortly after Thanksgiving I had dinner in California with Ronald Reagan's best biographer, Lou Cannon. Like many historians these days, we discussed whether George W. Bush is, conceivably, the worst U.S. president ever. Cannon bristled at the idea. Bush has two more years to leave his mark, he argued. What if there is a news flash that U.S. Special Forces have killed Osama bin Laden or that North Korea has renounced its nuclear program? What if a decade from...