This episode's headline: Nuclear Genie; House Divided; Just Doing It; Berlin Airlift. ANCHOR: JIM LEHRER; GUESTS: ASHTON CARTER, Former Pentagon Official; JOHN MEARSHEIMER, University of Chicago; JONATHAN SCHELL, Author; PHILIP KNIGHT, CEO, Nike Inc.; MICHAEL BESCHLOSS, Presidential Historian; DORIS KEARNS GOODWIN, Presidential Historian; HAYNES JOHNSON, Journalist/Author; ALEXANDRA RICHIE, Author; CORRESPONDENTS: PHIL PONCE; ELIZABETH FARNSWORTH; PHIL PONCE; ELIZABETH FARNSWORTH; SPENCER MICHELS; MARGARET WARNER; KWAME HOLMAN