“Future generations” are already here
The Journal of Public Economic Theory has a special issue on Managing Climate Change, to which they are providing free access (hopefully, this link will work). I’m mentioning it partly because I have an article which I think is really important, even though the point it makes is a simple one, and partly because any initiative to make important information more freely available (even a limite special case like this one) deserves some applause.
My paper is a bit wonkish, but the basic point is simple, and, I think provides a knockdown argument against any form of utilitarianism that discounts future utility (including those misleadingly referred to as future generations.
The paper gives a mathematical demonstration, but the key idea, stated in the introduction is a simple one
Much of the debate on the question of whether a pure rate of time preference can be justified is concerned with determining the appropriate way to balance the interests of “current” and “future” generations. The central question, in this framing of the problem, is whether, and to what extent, members of the current generation have the right to allocate resources in their own favour, at the expense of unborn future generations.
The central point of this note is to observe that this way of posing the problem is invalid, because members of different generations are alive at the same time. Any policy that discounts future utility must discriminate not merely against generations yet unborn but against the current younger generation. Assuming that members of any given generation are concerned about their own lifetime utility, rather than myopically concerned with current utility alone, a social allocation rule that incorporates pure time preference gives higher weight to the lifetime utility of earlier born generations than to their later born contemporaries. Assuming a 3% pure rate of time preference, as above, and 25 years between generations, the lifetime welfare of those aged 50 or more is valued twice as highly as the welfare of their children, and four times as highly as the welfare of their grandchildren, all of whom may be alive at the same time. This is obviously inconsistent with any form of utilitarianism in which all those currently alive are valued equally.
Furthermore, by the nature of overlapping generations, there is no point at which a coherent distinction between current and future generations can be drawn. In the absence of some general catastrophe, many children alive today will still be alive in 2100, at which time people already alive will reasonably be able to anticipate the possibility of survival well into the 22nd century.