In the voices of the Vice President, the National Security Advisor, the White House press secretary and various members of the Republican chorus on Capitol Hill, the Bush administration keeps answering questions that haven’t been asked—and avoiding questions that must be answered if the nation is to avoid an even worse catastrophe than that of Sept. 11, 2001. No serious person has asked whether George W. Bush or his aides knew in advance that terrorists were planning to seize civilian airliners and crash them into the World Trade Center and the Pentagon. And no serious person has suggested that Mr....