Slow Pearl Harbours and the Pleasures of Deception

Abstract

Quite a few years ago, prodded by Andy Marshall and some other friends with a close and long-term interest in intelligence, I looked into the question of why we were surprised at Pearl Harbour. I examined the signals available to us that pointed to an attack on Pearl Harbour and the background of ambiguities in which they were embedded. I looked at what we wanted to believe Japanese intentions to be, as well as what these intentions actually turned out to be. I found it useful to use some distinctions familiar to practitioners of the mathematical theory of information, although I did not and do not pretend to travel in the rarefied atmosphere even of the somewhat lower reaches of this theory. I have been, rather, a fellow traveller, with lots of friends.