The advantage of the term "multigenerational" is threefold. Firstly, it returns a sense of perspective that's often absent from purportedly "long-term" thinking. In a culture that has tended to operate on the "worry about tomorrow, tomorrow" model, looking at the next year can seem daring, and looking ahead five years can seem outrageous. But five years out isn't very long for long-term thinking; even ten years is better thought of as mid-range. Multi-generational, conversely, suggests that whatever we're thinking about may require us to think ahead 20+ years.

Secondly, it reinforces the notion that choices we make today don't just impact some distant future person (subject to discounting), but can and will directly affect our physical and cultural offspring. (Even those of us without kids of our own recognize that we have a role in shaping subsequent generations.) That is to say, "multigenerational" carries with it a greater implied responsibility than does "long-term."

Finally, it doesn't let us skip over the journey from today to the future. "Multigenerational" demands that we include generations along the way -- and while the core meaning of the term refers to human populations, one could stretch the concept to include other systems that show generational cycles.

This is a key difference between "long-term" and "multigenerational," but it's a subtle one. When we talk about the long-term, the corresponding structure of language -- and thinking -- tends to bias us towards a kind of punctuated futurism, pushing us to look ahead to the end of the era in question while leaping over the intervening years. This skews our perspective. "In the long run, we are all dead" John Maynard Keynes famously said -- but over that same long run, we will all have lived our lives, too.

I'm increasingly convinced that, when looking ahead, the focus should be less on the destination than on how we get there. Yet that's not how we discuss long-term issues. When we describe climate change as a long-term problem, for example, we inevitably end up talking about what it would look like down the road, after some "tipping point" perhaps, or at a particular calendar demarcation (2050 or 2100). Although there's no explicit denial that climate change is something with implications for every year between now and then, our attention -- our foresight gaze, as we might think of it -- is drawn to that distant end-point, not to the path.

My thoughts about "long-run" vs. "long-lag" problems cover a similar issue, looking at how our articulations of the future shape our thoughts of it. But this is a deeper problem, one that the "long-lag" concept only hints at.

"Multigenerational" has two drawbacks, however. The first is that, simply put, it's a bear of a word. Multi-syllabic, 17 letters in length, it requires a bit more effort than "long-term" to write or say. While not an insurmountable barrier, this does mean that sheer laziness will bias me towards "long-term."

The second is a bit more serious. As noted above, multigenerational implies looking ahead twenty or more years. If we consider a ten-year horizon to be the outer edge of medium-term, there's still the "near-long-term" range between ten and twenty years out to worry about. It's definitely not multigenerational -- hell, it's really not even generational. Yet it's still well beyond the comfortable "foresight window" for most people (which, in my experience, tends to be about five years). At this point, I'm likely to just roll that time range into multigenerational, but the inherent inaccuracy leaves me wanting a better solution.

I first started thinking about the multigenerational vs. long-term language a month or so ago, while talking with colleagues working on a new foresight-driven non-profit. Its utility was solidified, however, when Emily Gertz pointed me to this essay by science fiction writer and green futurist Kim Stanley Robinson, "Time to end the multigenerational Ponzi scheme," which looks out at what's needed to develop a postcapitalism perspective. KSR is one of the best world-builder science fiction writers out there, in my opinion, and he has an excellent sense of historical patterns. If he's taken to using "multigenerational," then I feel confident of its value.

Language matters, especially when considering something that's intrinsically conceptual rather than physical. "Long-term" has a lengthy (!) history and deep cultural roots; I expect that I'll find myself using the phrase for some time, even as I try to shift to "multigenerational." But right now we're facing a century of what could easily be the greatest overlapping set of crises our civilization has ever seen. If we're to get through this era intact, we'll need all the tools at our disposal -- and to be thinking about the consequences of our actions with as much acuity and clarity as humanly possible.