To round out this collection of essays, we are going to engage in a little speculation - we hope the reader will indulge us in this! We shall begin by noting that there is good and bad speculation and try to see what the difference is in terms of an example which is by now familiar: The dropping of atomic bombs on Hiroshima and Nagasaki. These are objective historical facts, so it seems that there can be no uncertainty about them. However, to this day there is considerable disputation about reasons: Why were the bombs dropped? What precisely was the advice given to President Truman? \Vhat exact­ly was the nature of the advice that swayed Tru­man's decision? (As an example of the controversy still generated by those events, we can mention a recent exhibition that was put on at the Smithsonian Institute in Washington dealing with the bombing. The exhibition was intended to be both commemo­rative and educational, but such was the furore that met the educational part that the exhibition had to be closed and its director resigned. See Harwit 1996).