This episode's headline: Hard Choices; Losing Ground; Second-Hand Risk; Dialogue; Generation Gap. ANCHOR: JIM LEHRER; GUESTS: SEN. JOHN McCAIN, [R] Arizona; SEN. CARL LEVIN, [D] Michigan; DR. ICHIRO KAWACHI, Harvard School of Public Health; CHARLES MOSKOS, Co-Author; JOHN SIBLEY BUTLER, Co-Author; CORRESPONDENTS: KWAME HOLMAN; ELIZABETH FARNSWORTH; CHARLES KRAUSE; BETTY ANN BOWSER; DAVID GERGEN; ROGER ROSENBLATT