One of the recurrent weaknesses of the imaginative reconstructions of a hypothetical past is that the line of inference is often drawn too far into the future. Not satisfied with reconstructing the given situation for a limited period, in which the succession of alternative happenings can be clearly envisaged, those who think through the process of reconstruction carry it indefinitely forward. They therewith tend to disregard the increasing possibilities of alternate developments as more and more elements enter the story. If a reconstruction over a period of a few years is risky, a reconstruction over a period of a hundred years is much more than ten times as risky. The following illustrations may make this clearer.
If Quebec had fallen to American assault in the War of Independence, we can safely predict that the war would have ended sooner than it did and that Benedict Arnold would have escaped the fate of a traitor. It is a safe prediction but not necessarily true because we are assuming that certain generalizations about the conduct of war and the behaviour of individuals like Arnold are valid. Although we have a right to make these generalizations on the basis of rules derived from past experience, we have no logical guarantee that they will continue to hold or that something new and completely unforeseen will not crop up to prolong the war and make a traitor of Arnold. We are assuming that other occurrences, happenings in other series of events unrelated to the series that followed the fall of Quebec, will not intersect the latter. But they may. That is why our judgment is well grounded and reliable but not certain. We can also predict, but not so safely, that if Quebec had fallen, the Canadian provinces, with their large French population only recently transferred to the English flag, would have raised no insuperable objection at the end of the war to incorporation in the United States of America. Here the possible number of disturbing elements from other series of events is larger, and the period of time over which they could interfere with what would otherwise have been the case is greater. But if anyone were to try to predict the effect of the incorporation of Canada upon the development of American economy and politics down to the twentieth century, his conclusions would be extremely improbable although not necessarily fanciful. He could make out a one-way case for the development of the series of events in relative isolation from other series of events, but we can see, on the basis of our knowledge of other histories, a vast number
