Thinking the Unthinkable. Herman Kahn, Weidenfeld and Nicolson, 25s.

Herman Khan’s central thesis in On Thermonuclear War was that with wide civil defence, nuclear war need not result in total devastation. This is, of course, perfectly acceptable—the only problem being one of degree. If everyone was evacuated to the moon, for instance, a nuclear war could be fought on earth with a very low casualty rate indeed.

His main concern in Thinking about the Unthinkable is to argue against the conventional picture of thermonuclear war. In the past we have talked as if the only kind of war possible is a “spasm” war. That is, both sides throw all they have at the other in one strike so as to do maximum damage. Without adequate civil defence measures such a war would undoubtedly produce something near total devastation in USA, Europe and USSR. Kahn’s main task in his new book is to discuss other kinds of nuclear war which could be fought. A war could, for instance, consist of a series of blackmailing, one-for-one city exchanges. At some point, he argues, one side could call a halt.

If such a war was halted in the early stages, a thermonuclear war would have been fought, and there would have been fewer casualties than during the Second World War.

Another possible type is the pure counterforce war—with or without major attempts to avoid civilian casualties. It is obvious that unless immense efforts were made to avoid civilian casualties, there would be little about such a war that was in any serious sense controlled. On the other hand, a war concentrating on military targets, avoiding cities, which would result in less damage than World War II, is theoretically possible. Kahn maintains that such controlled wars are feasible and that the USA should adopt a strategy which would impose this form on military conflict with the USSR. It should also adopt arms control measures to reduce the dangers of accidental war.

This thesis is now the accepted orthodoxy among western strategists. Kahn has achieved a justified notoriety among defence experts for his work in discussing these types of conflict. This reputation seems largely misplaced, and there are few of his conclusions which he has actually substantiated. The inadequacies of his approach can best be seen from an examination of his methods as he presents them. There is one chapter called “Some Strange Aids to Thought” in which Kahn discusses his three main procedures.

Kahn refers to physicists who “abstracted from real life situations the qualities they found most interesting and used calculations concerning these qualities to improve their understanding of the world about them”, and goes on to say that “starting from such models enables one to define language, form concepts and discuss and emphasize some elementary principles more clearly than by choosing examples of the real world”. What he means by abstract models are, for example, simplified descriptions of the respective military postures in terms of numbers, range, size, vulnerability, penetrability, etc. That is, the sort of material which McNamara feeds into his computers. The degree and extent of destruction comes out at the other end of the machine with a note saying “Won”, “Lost” or “Draw”. Kahn argues that missile warfare lends itself more easily to this kind of mathematical calculation than do previous types of war.