A Thread of Deceit by Nigel West (Random House: $16.95; 166 pp.)

This short book graphically illustrates how difficult, if not often impossible, it is to prove a negative. The author has set himself the daunting task of trying to debunk 10 of the “espionage myths of World War II,” including claims that President Franklin D. Roosevelt had advance warning of the Pearl Harbor attack, that Adm. Wilhelm Canaris, chief of German intelligence, was a British spy and that the Nazis were tipped off in advance about the Dieppe commando raid of 1942.

However unlikely these or others of the “myths” examined may be, West, a British writer who specializes in the subject of espionage, falls well short of establishing the facts in most of the situations. It soon becomes evident that his are shorthand arguments and that, even assuming all the facts are available, which they are not, a much more exhaustive treatment of each matter being considered would be necessary to adequately make the case.

What West does succeed in demonstrating is that espionage literature is often extremely confused and that the truth is elusive. He makes the point that since the facts of intelligence operations are so hard to come by, writers are frequently all too prone to copy one another. A mistake made by one will thus be repeated and even exaggerated to such a degree that, relatively soon, myth does take hold and something that may never have had any basis whatsoever may become widely accepted.

Saying this, however, does not justify any easy assumption that some of the matters discussed here are simply “myths.” The author sometimes seems too quick to ignore key arguments on the other side. For instance, in the Pearl Harbor chapter, he contents himself with explaining away certain allegations regarding advance warnings said to have come via agents in Europe. But he passes up altogether the argument that warnings implicit in decoded Japanese transmissions coming from Asia prudently should have been passed on immediately to American commanders in Hawaii and that the failure to do so may severely implicate the Roosevelt Administration. West is contemptuous of American writers, such as John Toland, who have made such arguments, but he does not adequately sustain his contempt. In any event, 17 pages is not enough to devote to the subject, and a similar point is applicable to other chapters.

Readers of this work should have some prior expertise in the matters reviewed. This is hardly a book for laymen.