I still hate this time of year. Though the post and comments are of generally high quality, and the introduction of actual Japanese scholars and sources into the debate is welcome, I still haven’t seen anyone address the “sufficient ≠ necessary” issue to my satisfaction. There’s an awful lot of post hoc ergo propter hoc in the discussion, as well as an awful lot of “plausible, therefore true” fallacies on the other side.
It’s really one of the nastiest questions of historical causality: there’s counterfactuals, personality/psychological considerations, cultural considerations, long-term strategic and moral implications, the inevitability trap, and self-justification and distortion in the sources on all sides, not to mention huge gaps in the record on critical persons and times. The problem, really, is to approach it the way we do every other historical question, because to treat it as a sui generis issue (which it really looks like) can lead to the use of arguments and methods which are unacceptable in other contexts (and should be unacceptable in this one).
Like Eric Rauchway, I rarely spend a lot of time on the atomic bombings in either my World History or Japanese history courses, partially because, like him, I put it in the context of the general escalation of air war and military technology (a theme that runs through my World courses in particular) and partially because the debate is driven more by ethical than by historical questions. Otherwise we would have moved on ages ago, because the consensus position of Japanese historians reached almost a half century ago still largely stands: The combined shock of the atomic bombs and Soviet entry pushed the Japanese cabinet to the point where they could accept the unconditional end of the war, but things happened so fast that there’s really no way to tell whether one or the other would have been sufficient in isolation, nor can we know for sure whether a conditional surrender could have been reached earlier because nobody tried very hard.
Had you been an infantryman in the obscure 96th Infantry Division during the Pacific War, you would not have cared one whit for “counterfactuals, personality/psychological considerations, cultural considerations, long-term strategic or moral implications” of the bombings. Rather. you’d have been counting yourself lucky to have survived Okinawa (nearly 3,000 of the division killed in action, over 10,000 seriously wounded) and have been dreading the hardly unexpected news that your division was slated for the invasion of the Japanese homeland. The fact that the Russians joined the war in the Pacific on 9 August would have meant little. They were, after all, a land army, with only limited means of projecting their power across the Korean Straight.
I have little doubt that is true. Which is one reason it is fortunate that soldiers such as those of the 96th Infantry Division weren’t left with the heavy responsibility for making those fateful decisions. These annual debates, especially among historians of Japan and Asia are important ones, for they help historians participate in the discussion of where we draw the lines of human decency.
As an historian, it is my job to be concerned with historical causality. The attitudes of the many US and Japanese military personnel and civilians is an historical datum, not an historical investigation or argument.
In fact, the Soviet entry into the war was very important. Not because they could invade Japan — though they did immense damage very quickly to the remnants of the Kwantung Army and Korea was considered part of Japan at the time — but because it meant that Japan was completely encircled by enemies. Instead of “bandits” on the continent, they faced one of the great war machines of the 20th century. The psychological effect on the leadership is very well documented.