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?