NOT long before our nation launched the invasion of Iraq, [the US's] longest-serving senator, Robert Byrd of West Virginia, stood on the Senate floor and said: "This chamber is, for the most part, silent: ominously, dreadfully silent. There is no debate, no discussion, no attempt to lay out for the nation the pros and cons of this particular war. There is nothing. We stand passively mute in the US Senate." Why was the Senate silent? In describing the empty chamber the way he did, Byrd invited a specific version of the same general question millions of us have been asking:...