WASHINGTON — There was the sense in the capital last week, as the Senate began debate over the future of the filibuster in judicial nominations, that the country was on the brink of a revolutionary break with its traditions, barring a last-minute compromise. Depending on your political persuasion, that meant liberating the Senate, and the people's will, from an obstructionist minority or, on the other side, damaging the Senate and threatening one of the nation's fundamental protections against the tyranny of the majority. Both Republicans and Democrats claimed that the other side had embraced intransigent radicalism. But historians and political...