I've been thinking about this because of a couple of books that I'm reading right now. Historical anachronism is one thing--you don't see it very often, because books have editors, and everybody knows that there were no handguns in medieval times or cellphones in World War II. Science fiction is iffier, because sometimes you do run across a moment of insufficient imagination, where you want to ask the author: do you really think that people who are neurologically hardwired to the net are going to even know what paper is? If they're using lasers to cut steel, are they really still using projectile weapons? That kind of thing slips through sometimes.
But whether you go backward or forward, something that always throws me off is emotional anachronism. This is actually a pretty common problem, because an author is, almost by definition, writing for his or her contemporaries, and therefore often providing them with characters they can relate to. Our heroine should be spunky, our hero fiercely independent, our genius thinks outside the box. The characters we're supposed to hate stand for things we dislike--control, oppression, greed. Our protagonists yearn, dream big, want more. I would expect nothing less from my characters than to recognize in them the same ambitions and fears that I have, translated into their own set of circumstances.
This isn't always realistic, though. Take Inside Out, by Maria V. Snyder (author of the fabulously fun Poison Study and a number of convoluted, jump-cut action-packed sequels). This new book takes place in a future world where society exists in an enormous complex, Inside, and Outside is a rumor. The Uppers live comfortable lives; the scrubs are packed into small spaces and do little more than work and sleep. Trella (our heroine) is skeptical, idiosyncratic, and wants more.
Now, they have their own system of timekeeping, and a little math makes it clear that we're talking 1500-ish years in the future (give or take a few hundred, but you get the idea). Education is minimal, propaganda rules all. There are a lot of details in this story that don't follow from this information. Things like why Trella is even aware of the fact that there's an old way to count years (okay, maybe that was thrown in for the less mathematically inclined among us, but still, there are other details that she knows from our 'past'). Why are all the scrubs suddenly seething with dissatisfaction, if this is all they've known for generations? There's no indication of the incremental changes to thought that ended the thousand years of mental torpor that kept serfs out in the cold in Europe. There's no Renaissance to lead into the Revolutions--just suddenly it's there. Where do these characters come by their subversion?
The answer is that we, the readers, respect it, and expect it. We believe that we would not be cowed, we would not be sheep, even if we had never known anything else. We picture our current selves put into a new environment, because we cannot imagine who we would be in another world. I'm having trouble with the authenticity here.
Going the other way--away from familiarity and into realism--has its own problems. The other book I'm in the middle of (have been for a while; now I'm waiting for the library to lend it to me again) is The Owl Killers, by Karen Maitland. This book takes place in the 1300s in England, and woah, Nellie, realism is not a problem. In fact, everyone is so poor and ignorant and narrowminded that it's hard to like any of them. The story is told by a series of narrators--women from Bruges, a priest, village children--and each of them is exactly who their world has made them.
The children are hungry and needy and shameless about doing what they have to to live. The priest is intolerant, because he doesn't know how to be anything else. The few characters who are somewhat outside of society--the women in their communal house, the bookish daughter of a local lord--appear to us just as odd as they would to their neighbors--standoffish, selfish, stiff, strange. This world doesn't honor the same traits we do, and doesn't leave any room to be anyone I can see myself in. The book is authentic, but a little hard to read for all that.
It's a hard call to say where I come down on this issue. Emotional resonance, and the truth that carries with it? Or historical truth, and the new ways of thinking that opens up, hopefully followed by new emotional resonances of their own? Or maybe (isn't this always the answer?) something in between.