According to one prominent school of thought, politics is mysterious and largely unknowable terrain. Ask politicians, the journalists who cover them and the consultants who advise them and they will tell you theirs is a dark art, subject to quick, quirky and mystifying shifts, dependent on contingent events and instincts.
Not for nothing do they insist that in the world of politics, "an inch ahead is darkness."
A second school argues that this is nonsense. Its adherents contend that careful statistical analysis is an accurate predictor of political outcomes. No one has made this case more persuasively than Mr. Nate Silver, a blogger whose spectacular record predicting U.S. campaigns has upended the conventional wisdom about politics and political analysis.