> I see your point, but I have a hard time not thinking that Stalin had a
> few Kangaroos loose on the top paddock, even knowing fully well the
> extent of his rationality.
I wondered this same thing a couple of months ago: how could any but a madman order the purges? Eventually I got curious to see if there was any competing explanation that was plausible and searched through the archives for what Justin once said was the definitive book on the purges, the first ever to use hard archival data made available by glasnost: _The Origins of the Great Purges_ by J. Arch Getty.
Getty's argument in a nutshell is that the inescapability of Stalin's madness is based on two completely wrong suppositions that pretty much ruled the field of Soviet studies before his book: (1) that the Soviet Union in the 30s was a totalitarian state, that is, that it controlled and was informed about every aspect of everyday life; and (2) that Stalin exercised total control over the bureaucracy. He argues on the basis of his substantial and unprecedented data that this was completely wrong: the bureaucracy was such a mass of confusion that it could barely be called a bureaucracy; and it was riven with factions that warred against and often liquidated each other based on trumped-up charges. The oscillation of who's on top led to wildly oscillating changes of favor and policy.
If I read Getty correctly, it is our personalization of this phenomena into "Stalinism" that leads to the unavoidable impression that Stalin must have been stark raving mad, because no sane person could backed all these policies or these abrupt changes in them. But in fact, the total incoherence was a feature of the political system, not of his mind. And furthermore, it seems that when analyzed in close detail, it was really a feature of the political system during a narrowly defined period of crisis during the 30s. It seems that Fainsod and others made it all much more coherent than it was, projected it forward and backward, and then, having produced a supremely irrational supercoherence, explained it all as a function of Stalin's madness which was then embodied in institutions.
This is not meant to foreclose the possibility of Stalin's madness, but rather to unforeclose the possibility of his being simply ruthless and rational. It seems that, when you add in that lots of the purges were conducted not by him but by local officials who systematically lied to him, and that his ignorance of their actions was vast, it is possible that his direct orders were to kill a much smaller number of enemies that he actually believed were involved in a series of conspiracies to kill him. And that such a belief was not entirely irrational.
Lastly, according to Getty's bibliographical essay at the back, it seems that pre-Glasnost Soviet studies, besides being supremely ignorant of the details of what actually went on during the purges, was also extremely credulous when it came to incorporating unverified rumors into their theories as data. This was arguably an unavoidable result of being completely cut off from hard data. But much of the rumor was originally bruited by sides locked in combat trying to discredit each other. These were repeated for decades with the air of almost US State authority until they took on the aura of unchallengable truth, and they still compose the interpretative background of almost all non-scholars of the period. They also add to the impression of madness; some of the really mad policies turn out to be only mad rumors.
Getty argues that part of the problem with the totalitarian argument was that it completely misinterpreted the famous cult of personality. For him, rather than being an expression of meglomania, the cult of personality was mainly a political tool, and it was mainly used not by Stalin but exactly by these warring factions that he didn't control -- it was important for each of them to justify any change in policy, and especially an abrupt one, by appeal to a godlike deity that could never be wrong. Not that Stalin didn't use the cult himself -- but that's the point, it was something to use rather than the excrescence of a diseased mind. Supposedly in person he was famously for his modesty.
To be fair, that's my impression on a brief skim-through, and even if I read the book thoroughly, I am by no means a scholar of the subject. The man to talk to is Justin (aka Andie Nachgeborene aka jks), who is.
Michael