This episode's headline: Day of Decision; Gergen & Shields; Conversation; Back to Basics. The guests include NINA TOTENBERG, National Public Radio; DAVID GERGEN, U.S. news & World Report; DR. DAVID KESSLER, Food & Drug Administration; CORRESPONDENTS: ROGER MUDD; CHARLAYNE HUNTER-GAULT; FRANK DEFORD; KWAME HOLMAN. Byline: In New York: ROBERT MacNeil; In Washington: JUDY WOODRUFF