John Ydstie goes to a club called the Birchmere in Alexandria, Va., to hear the opening act, Mary Gauthier. Gauthier was an adopted child, a troubled teen, then a philosophy student, and later a restaurant owner. Now she writes and sings songs. Mary Gauthier talks about songwriting and how it relates to philosophy. (12:30) Mary Gauthier's new CD is called Filth and Fire It's on the Signature Sounds label.