Can non-overlapping generations engage in conflict with each other?

Here’s a widely-shared and I think quite compelling thought: the present generation has a moral duty to not wantonly destroy our planet’s natural and cultural wonders—from the Great Barrier Reef to Machu Pichu—and to not rapaciously over-consume the Earth’s non-renewable resources, so that future generations can enjoy them too. If you’re like me, you not only agree with this claim, but you also think something stronger; that this is not just any moral duty, but a duty of justice. This raises a well-known challenge for the many philosophers who think that duties of justice hold only between those who can cooperate for mutual advantage. For, at least at first, it seems hard to see how generations who never overlap could nonetheless cooperate with each other.

Some philosophers, however, think they can. To take one recent and intriguing proposal, Anja Karnein (2022) argues that non-overlapping generations cooperate when they responsively pursue shared aims for mutual advantage. Her central example is the building of a cathedral, many of which throughout history have been completed over many non-overlapping generations. If the masons who started work on Saint John the Divine, she supposes, did so knowing they would not live to see the project completed and so left careful notes and plans for their later twenty-first century counterparts, who in turn continue construction explicitly guided by those earlier masons’ dreams and designs, and if we also allow that one can be benefited posthumously by the continuation of one’s projects—especially if they are completed in part due to one’s own causal and normative contributions—then it seems indeed that we have a case of members of non-overlapping generations responsively pursuing shared aims for mutual advantage, and thereby cooperating.

Suppose Karnein and others who agree with her conclusion, even if for different reasons, are right. I think this leads us to an interesting, under-explored conceptual question. If non-overlapping generations can cooperate with each other, can they engage in conflict with each other too? After all, it would be somewhat odd to claim that although two parties can cooperate, they cannot engage in conflict. There is at least a surface-level similarity in the conditions of possibility for these two relations that’s worth exploring here.

It will help, though, to be clear what we’re not asking. We’re not questioning whether members of different but contemporaneous birth cohorts can engage in conflict; their contemporaneity ensures that they can. Nor are we casting any doubt on the rather mundane observation that the interests of non-overlapping generations can conflict; that, to return to our earlier example, our rampant use of non-renewable resources means less for those to come. Rather, the question concerns whether there is any interesting sense in which members of non-overlapping generations can engage in conflict with each other in the richer sense of that phrase that we might associate, broadly speaking, with two companies actively undermining each other as they compete for market share, or two nations going to war.

You might think the answer is a rather obvious No. Conflicts, in this richer sense, surely require a kind of symmetry of participation that is lacking in the case of non-overlapping generations; echoing a related concern expressed by Scott Shapiro (2014) in the context of intergenerational cooperation. Suppose the present generation, in a collective fit of historically-directed pique, decides to blow up that cathedral that generations long past worked tirelessly to construct, perhaps because it symbolized for the latter a great value or belief system to which they were committed, one that the present generation feels the need to explosively repudiate. Even if we grant that doing so posthumously sets back that past generations’ interests, they will evidently never be able to hold the current generation to account, never be able to retaliate, nor ever even know of the current generation’s act of aggression towards them. Things just seem too one-sided for the case to be aptly described as members of two generations engaging in conflict.

Yet this may not be all there is to it. Consider now the prospect that, as human technological sophistication develops, generations in the medium but not too distant future might find themselves with a species-scale existential decision to make. Do they artificially enhance themselves to the point where they are no longer recognizably homo sapien, perhaps to become vastly more intelligent and peace-loving, letting our species gradually come to an end—at least outside of whatever kind of holographic history books they then possess? Or do they reject the post-humanist path in favor of preserving the quintessentially human, the species that has come so far from such humble beginnings and, for all its many shortcomings, might nonetheless represent something of great value in its persistence?

Suppose we the present generation desperately prefer the human race to continue—wars and all if that’s the price to pay for it—but fully expect this later generation to be unable to resist the attempt at post-human transcendence. We thus set about constructing multilateral treaties prohibiting trans- and post-humanist research, establishing legal obstacles to the implementation of such policies at every turn, and attempting to instill a global public pro-humanist ethos in the hope that it will endure down the generations. When their time comes, however, that later technologically sophisticated generation does indeed, as we expected, become overtaken by post-humanist fervor, annuls our treaties, removes our legal barriers, and deliberately forges ahead with what they know to be counter to their ancestors’ wishes. If responsively pursuing shared aims for mutual benefit suffices for cooperation between non-overlapping generations, as Karnein claims, then it’s interesting to note that we perhaps have here a case in which two non-overlapping generations pursue starkly incompatible aims grounded in incompatible interests in ways explicitly, and negatively, responsive to each other—pre-emptively responsive to the expectations one has of the other in one direction, and responsively trying to undo past actions in the other. This is starting to at least seem like a case of conflict between non-overlapping generations in the interesting sense. Not that Karnein is committed to this conclusion, of course. Nor should we be, for all I’ve said here.

What if it is such a case though? Would any significant normative upshots follow from the possibility of this sort of intergenerational conflict? Would being engaged in one affect the nature and extent of the generations’ independent duties of justice towards each other? Would either have a duty to engage in some kind of appropriate conflict resolution, presumably one that differs in its requirements, proactive or reactive, depending on whether they find themselves at the tail or tip of time’s arrow? These strike me as interesting questions to explore.