by Walter Isaacson. putnam’s, $18.95. Mr. Isaacson has discovered, via Protagoras, that “there are two sides to every question.” He has therefore selected what he considers the major unsettled questions of our day and summarized the arguments on either side of each, reinforcing their points with statistics (if available) and quotations from authorities (often self-appointed). The topics proceed from Abortion to Voluntary Euthanasia, encompassing along the way the Designated Hitter Rule, Old Movies, and Returnable Bottles. Since Mr. Isaacson has been meticulously fair in collecting the best arguments offered on either side of every case, including Flat Earth, his book is not likely to change any reader’s settled opinion about Gambling or OneTerm Presidency, but it provides enough information to keep cocktail-party debaters in full cry for hours. Perhaps significantly, Noise Pollution is not on Mr. Isaacson’s index.