In Purpose in the Universe, Tim Mulgan writes:
Reciprocity, sentiment, and mutual cooperation may provide good foundations for intra-generational ethics. But intergenerational contracts face two barriers: Parfit’s non-identity problem and the impossibility of reciprocal interaction between present people and distant future people. How can we begin to imagine contracts, bargains, or cooperative schemes involving future people whose existence and identity depend on what we decide and whose fate is entirely in our hands? (p. 24)
I discussed the threat that the non-identity problem supposedly poses to T. M. Scanlon’s contractualism in a previous post, which you can find here. I’m not very satisfied with that post, but I stand by the main idea. The key point is that Parfit’s non-identity problem depends on a criterion of identity that not even Parfit accepts. At worst, the non-identity problem only bars contractualists from accepting a certain criterion of identity. But because contractualism presupposes no particular theory of personal identity, this restriction poses little threat to contractualism as such.
Having dealt with the non-identity issue elsewhere, here I want to discuss the second barrier Mulgan thinks contractualists face in explaining obligations to future people: the impossibility of reciprocal interaction between present and (distant) future people. In his earlier book, Ethics for a Broken World, casts a very broad net, with the claim that all social contract theories require reciprocal interaction between rational self-interested parties. However, this is not true of Scanlon’s social contract ethics. The parties to Scanlon’s hypothetical contract are explicitly not defined by motives of rational self-interest, and they are not stipulated to be engaged in reciprocal interaction. They are reasonable persons motivated to find mutually justifiable principles of conduct. (What We Owe to Each Other, p. 191) The source of this motivation is the value of a relationship structured by such principles — a relationship of mutual recognition. (p. 162)
However, Scanlon’s contractualism is not an account of political justice, and if we acknowledge the moral urgency of future people’s interests, questions of intergenerational political justice are especially pressing (for just the same reasons that questions of political justice among contemporaries are especially pressing). A theory of justice generated from within Scanlon’s more general account of what we owe to each other may also turn out not to assume reciprocal interaction, but because such a theory does not yet exist, it cannot be cited in defence of contractualism’s ability to explain obligations of justice to future people. And existing contractualist theories of justice do tend to assume reciprocal interaction. So contractualists must show that there can be reciprocity between past and future.
In his 2012 Tanner Lectures on Death and the Afterlife, Samuel Scheffler explores the significance of what he (somewhat cheekily) calls “the afterlife”: the fact that other people will continue to live value-laden lives after we ourselves have perished. Scheffler argues that our horror at scenarios like that of Children of Men, in which human reproduction has (non-voluntarily) ended and the species will therefore soon become extinct, is best explained by a relationship of dependency between the value of our lives and the value of future lives. Apart from purely hedonistic pursuits, almost all our activities and projects would seem largely pointless if we knew we were among the last generations. But our own deaths do not similarly threaten the value of our lives (indeed, in the third lecture included in the volume, Scheffler argues that our deaths are a necessary condition for the value of our lives). We have self-interested reasons, Scheffler argues, to be more concerned about the survival of complete strangers in the distant future than about our own personal survival!
A vivid example of how this works can be seen in the film Star Trek: First Contact, in which the crew of the Enterprise travel back in time to 2063, shortly before the invention of the warp drive that made possible the thriving interstellar civilization of the future. In their own time, the warp drive’s inventor, Zefram Cochrane, is revered as one of humanity’s greatest heroes, and there are schools, statues and starships named after the man. But the crew is dismayed to find that the Zefram Cochrane of 2063 is a selfish, uncouth boozehound, not the visionary scientist found in their history books:
You wanna know what my vision is? Dollar signs, money! I didn’t build this ship to usher in a new era for humanity. You think I wanna see the stars? I don’t even like to fly! I take trains! I built this ship so I could retire to some tropical island filled with naked women.
A jaded survivor of Earth’s catastrophic final world war, Cochrane seems to see nothing potentially valuable in his life and works aside from opportunity for individual hedonistic pursuits. But meeting the crew of the Enterprise helps change his perspective. Cochrane will not live to see the founding of the great multi-species federation on whose behalf the Enterprise goes voyaging. But thanks to the visitors from the future, he does get a glimpse of the world that lies ahead for humanity, and it seems to change his perspective on his own life. The turning point is not finding out that he is honoured as a great man in the distant future (in fact, this causes him some distress), but rather finding out what that future is like.
I don’t think you need to be the inventor of the warp drive for this change in perspective to be reasonable. If there is no future — or at least no meaningful future — for humanity, there is very little to care about in the here and now; only if there is a meaningful future can we reasonably value much of what we actually do value. The value of our lives depends on the lives and labours of people in our distant future, just as the value of Zefram Cochrane’s life so clearly depended on the lives and labours of people in his distant future.
By itself, Scheffler’s argument reveals only prudential reasons for us to be concerned about the future long after our deaths. But this prudential concern for the distant future gives the people of distant future a measure of control over how our lives go. If future people make a very bad mess of things, that is very bad for present people. If future people do a very good job, that is very good for present people. Reciprocal interaction is possible after all. So the reciprocity condition is satisfied; our prudential reasons for caring about the people of the distant future can ground further, moral or justice-based reasons for caring about the distant future, via a social contract.