"There are ever so many ways that a world might be; and one of these many ways is the way that this world is." ~David Lewis (On the Plurality of Worlds, Blackwell, 1986, p. 2)
On comedy show Saturday Night Live last week there was an ingenious opening segment featuring Al Gore, playing himself in a parallel universe in which he'd beaten George W. Bush and been elected 43rd President of the United States. Anyone paying attention to the Presidential contest in 02000 knows how close it came to happening that way. At a personal level, not everyone has a "what if" story as dramatic as Gore's, but it's salutary to think back on our own lives about the chance events, serendipities and unlikely twists of fate which sent us down one path rather than another: people we almost didn't meet, opportunities that happened to catch our attention; and other forks in the road...
Now, I have no hard evidence for this -- it's more of a sneaking suspicion -- but it seems to me that people unaccustomed to futures thinking may actually find it easier to entertain alternate histories than alternative futures. There's a superabundance of literature out there dealing with these counterfactual "what ifs" in terms of alternate histories. (See the alternate history website Uchronia -- formed from the Greek ou- "not" and chronos "time", c.f. utopia, "no place" -- or this Counterfactual Thinking page, for a philosophical introduction.)
At first it seemed to me that this might be the case because when it comes to past events, we can easily resort to a "default" story (whether personal memory, or the historical record) to use as a springboard for thinking how things could have been otherwise... but then, we also have that for the future, don't we -- continued growth, anyone? So the existence of a baseline or default story might not be the key factor; although the availability of specific reference points in memory (decisions made, random events, etc) surely helps bring the "reality" of these past alternatives much more alive to us.
My thinking now is that it may be easier for many people to think about counterfactual histories than divergent futures because in the former case we're relieved of the need to "get it right", and can explicitly situate ouselves in the realm of imagination, and feel safe about doing that. In the latter case, however -- the imagining process ("futureS") constantly gets mixed up with the desire or habit of evaluating predictive correctness ("The Future"), which keeps reining the imagination back in. Hence, the heuristic value of Dator's Second Law: the reason to entertain "ridiculous" ideas about futures is that they give licence to the mind to soar.
Could this perhaps be a kind of cognitive bias that serves to help us avoid the paralysis of having to consider too many alternatives, prospectively?