Will our descendants be better off than we are? Cornucopians say: Yes, most likely. Cornucopians exhort society and in particular environmentalists to forego their pessimistic fears about the future. Cornucopians would of course not view their own stance as an instance of replacing pessimism by optimism but rather as an instance of realism: They consider the prediction that future generations are much better off than we are the most sober and plausible estimate.
It matters tremendously whether cornucopians are right or not. If our descendants can actually be expected to be significantly better off than we are, then there is a strong case for diverting resources from climate mitigation – and other investments into the future – into projects with a focus on the present such as poverty relief.
My big problem is: I find it extremely hard to make an empirical case for or against cornucopians. Both sides of the debate seem to rest their case mostly on gut feeling (and distortions by self-interest, by a human propensity to apocalyptical thinking, etc. do their fair share in influencing that gut feeling). If one wanted to have a reasoned debate based on empirical grounds — where would one start? If one had to make a bet about the level of welfare in 200 years, how would one rationally go about in placing one’s money? What evidence could we cite to refute or support the cornucopian predictions?
One place to start would be to look long-term economic models (they usually predict strong growth over the next century). However, these models seem to presuppose a cornucopian growth idea rather than to arrive at it. Another strategy for replacing gut feeling with argument would be to extrapolate past growth rates (One would then have to make a case why one chooses to extrapolate the last, say, 50 years rather than, say, the last 5000 years). A third approach would start from the extrapolation, too, but enrich it with innumerable bottom-up considerations about relevant factors that affect the growth or de-growth trend. The most prominent such relevant factors would be looming environmental catastrophes, assumptions about human ingenuity, guesstimates on political stability, population growth, etc.
Any help would be appreciated. My basic question is: What methods are there for going beyond a basic faith or gut feeling for the purpose of adjucating cornucopian “predictions”? What types of empirical evidence can be given to make a real case for or against the cornucopian idea?
Ethics for a Green Future 
One thing that makes this a difficult problem is that we know so little about the preferences of future people. Of course we know that they’re going to want things like enough food and clean water, and we can make a pretty good guess that they will (or, some would say, at least *should* want) things like unspoiled forests. But *how much* will they care about all these things? Joerg Chet Tremmel’s *A Theory of Intergenerational Justice*–which has the most extended treatment of this question that I know of–makes a pretty compelling case that there has been a strong long-term trend over the past couple of millennia toward what most of us would consider better living standards. (He doesn’t buy into claims about ‘primitive affluence’.) But his analysis tends to assume that everybody wants pretty much what most 21st century people seem to want–e.g., good health and education. On that account we’re much better off than people in the Middle Ages. But it wouldn’t surprise me if ancient Greeks or mediaeval Europeans didn’t see it this way. Perhaps they would pity us for having lost the opportunity to win undying glory in battle, or for living in a godless era, estranged from the true faith and Mother Church.
Another related issue is how substitutable resources are–i.e., how willing will people be to accept fewer trees in exchange for more washing machines? There’s an excellent discussion of this in Eric Neumayer’s 1999 essay ‘Global warming: discounting is not the issue, but substitutability is’.
While I agree that whether future people are likely to be better off is an important question, and worth thinking about, for two reasons it seems to me less decisive than is often thought. First, even if future *humans* are better off, it seems a pretty good bet that future non-humans won’t be, and there are a good deal more sentient non-humans than humans (largely birds). Policies that, say, promote global warming are probably a bad bargain all things considered even if they’re a good bargain for humans. The other issue is risk. At best we can say that future people *probably* will be better off. But the downside of being wrong–say, ten or twenty degrees of warming and a permanently impoverished planet–seems to me a great deal bigger than the upside of being right, so long as we don’t greatly discount the future.
Perfect thoughts! (And, btw, I also liked — most of — Neumayer’s essay)
The point about animals is interesting — and not noticed enough at all.
…After I read your comment I also realised how incomplete it was to talk about the simple question “Will future generations be better off than we are?”
…The much more sensible question is: “IF we pursue policy X today, how well off will future generations THEN be?” and the even more sensible question is: “IF we pursue policy X today, what probability distribution over future welfare can we THEN expect?”
…And once we ask THIS question, my worry about not being able to cite evidence dissovles immediately. For at least some policies X, there is readily available evidence that the probability distribution over future welfare is such that it includes a non-negligible probability of unacceptable outcomes.
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