If by "broad contours of history" one is referring to time spans of millennia then there is probably no disagreement and we are all Tolstoians. But if we look at history as the concrete events in a span of a few generations this is far from obvious. Who can say what the first centuries of the Roman Empire would have looked like if no conspiracy to kill Caesar had succeeded? (would our eighth month be named "August"?) Would a Hitler have arisen if the conspiracy to kill Archduke Frantz-Ferdinand had failed? Would Jim Crow have developed if Lincoln had survived the Booth conspiracy? Would American racial politics--indeed American politics itself--be what it is today if no conspiracy to kill Martin Luther King had succeeded? What would the fate of Athens have been if the conspiracy ("affair of the herms") against Alkibiades had failed? Indeed, if the Emperor Julian had survived the conspiracies against him would the "broad contours" of our present history have even included such a phenomenon as Christianity?
Of course these questions can only be answered in fantasy, and all fantasies are at least roughly equal. The point is that in the actual course, as distinct from the "broad outlines," of history, conspiracies when successful constitute crucial *moments* and historical actors ignore them at their peril. This is all too evident after September 11 last when something awfully like the stench of a burning Reichstag is so evident to any normally sensitive nose.
Shane Mage
"Thunderbolt steers all things."
Herakleitos of Ephesos, fr. 64