By Gilbert Cruz
Updated February 23, 2007 05:00 AM

”Why are you poor?” asks Vollmann in his probing philosophical essay. The author of Rising Up and Rising Down, a daunting seven-volume history of violence, is smart enough not to try to offer any solutions to the problem of poverty. His book is sweeping in its scope (touching on every continent save, obviously, Antarctica) and its methods (incorporating oral histories, straightforward journalism, and his own experiences with homeless neighbors). In that self-reflective chapter (”I am sometimes afraid of poor people”), he personalizes his sometimes obtuse musings, producing an intellectually rigorous yet ultimately humane work. B