Spike Lee is one of the most passionate and committed fans of the New York Knicks—not to mention one of the most celebrated filmmakers of our time. Underdogs for many years, the Knicks are enjoying a renaissance, and Lee is in his glory. David Remnick and Vinson Cunningham called Lee to talk about a life of fandom, the politics of activism in the N.B.A. and the N.F.L., and Lee’s multipart documentary about life in New York since September 11th, which will be released to mark the twentieth anniversary of the attacks.