The discussion of "War and Peace" started by Language Hat made me want to try to participate:
"Interesting thing I have observed over time, as my interests made me witness numerous debates on the "laws of history" is that participants are rarely given to moderation: it's either all chance and "great men", or all "laws of history".
I guess the great philosophical systems of the past centuries have accustomed us to there being a complete non-contradictory answer to all meaningful questions. So the lack of historical significance of the personality of one George W. Bush is taken as evidence of all personalities being relatively unimportant to the course of historical events; if, as this view implies, there were an over-arching theory of historical probability, this would be a valid approach, just like 2x2=4 would be sufficient to prove that 3x2=6. But this is emphatically not the case in history. The historian begins where the natural scientist stops: it's all about the particulars. Every imaginable theory can find its "confirmation" in the huge mass of known facts: you just have to choose the right facts.
There definitely were personalities whose presence or absence was not, as far as we can know, demonstrably important for the course of historical events. There also were historical events that changed the world beyond recognition, and pivoted on presence, absence, and whims of a particular person. For example, not jut the event itself, but the timing and course of World War I defined everything for the history of the next century; even if we agree that _some_ war was inevitable, the timing, and the course of it could well have been different, and depended on personalities in a lot of cases. The personality of Henry VIII is a visible cause in a lot of events that shaped the next two centuries of British history. Yes, it's open to question if Alexandre was really a genius and if his military skill was indeed important in conquering Persia; but without him the Greeks (well, the Macedonians -- some say there were more than enough Greek mercenaries fighting on the Persian side) would not have gone that far in the first place."
Overstating my case, going far beyond my field of competence... Well, that's what blogging seems to be for.
9 hours ago