"Conservatives . . . may decide to join the game and seek activist judges with conservative views. Should that come to pass, those who have tempted the courts to political judging will have gained nothing for themselves but will have destroyed a great and essential institution. . . . There are only two sides. Either the Constitution and statutes are law, which means their principles are known and control judges, or they are malleable texts that judges may rewrite to see that particular groups or political causes win."