I agree that people argue that democracies are more stable (though usually they just assume it), but the lists of unstable democracies and stable autocracies ar

I agree that people argue that democracies are more stable (though usually they just assume it), but the lists of unstable democracies and stable autocracies are both incredibly long. At the very best, there may be a rough correlation between stability and democracy; I rather suspect an anti-correlation, but in any case I don't see anything that would justify the blithe yet pervasive confidence of democratic stability exemplified by the assertion quoted in my original comment.