1. Introduction
In a paper published after his death, Derek Parfit asked of us:
Suppose we discover how we could live for a thousand years, but in a way that made us unable to have children. Everyone chooses to live these long lives. After we all die, human history ends, since there would be no future people. Would that be bad? Would we have acted wrongly? (Parfit Reference Parfit2017a: 118)
To many of us, including Parfit, the answer is Yes. Assuming future people will enjoy a high quality of life, it would be very bad if humanity went extinct, and that badness gives us reasons to want human history to continue (Parfit Reference Parfit1984: 453–4). However, some have argued against this view. Even if these additional lives would have been worth living, they maintain, there would be no one who would actually be harmed by our choice. For instance, Scanlonian contractualists claim we wrong others when we fail to consider their interests in our moral deliberations, and only people who either do or will exist have interests that are in need of our consideration (Finneron-Burns Reference Finneron-Burns2017: 331).
Scanlon's plausible version of contractualism is not alone in claiming we do nothing wrong by allowing human extinction in this way. Various theories, including other forms of contractualism and person-affecting consequentialism, reach this conclusion for similar reasons and are neither misguided nor obviously incorrect. While not wishing to downplay the differences between these theories, we believe that their advocates miss an important point about the ethics of human extinction. We shall therefore proceed on the basis that all these theories accept something like the following principle which, following Parfit (Reference Parfit2017a: 136), we call the No Complainants Claim:
No Complainants Claim: An act cannot be wrong unless there is or will be someone whom this act wronged.
Even if we were to accept that creating happy people is, in some way, good for them, the adoption of the No Complainants Claim means that if we do not create a happy person, there is no person whom we will have failed to benefit, and thereby wronged.Footnote 1 For theories that accept this claim, or something like it, it seems human extinction could only be wrong insofar as it negatively impacts currently, or at least necessarily, existing people (Finneron-Burns Reference Finneron-Burns2017: 338; cf. Frick Reference Frick2017).Footnote 2
We will argue that this implication is mistaken. Choosing to end human history would wrong our forebears by making their sacrifices less worthwhile. More precisely, if we were to allow our species to go extinct, then we would fail to be appropriately sensitive to the moral reasons that flow from the harms suffered by our ancestors when they made supererogatory sacrifices for the good of posterity. Therefore, views that incorporate the No Complainant Claim should also find that the value of future lives gives us at least some reason not to bring about human extinction, even if everyone currently living benefited from this choice and were willing to consent to it.
2. Moral worthwhileness
We begin by drawing out an intuition about the moral worth of sacrifices. Consider the following case.
Liver Transplant. Through no fault of his own, Jeff is very sick. He desperately needs a liver transplant. Though he is not obliged to do so, a stranger called Michael gives Jeff part of his liver at the cost of reducing his own lifespan by ten years. After the procedure, Jeff drinks heavily, and he dies from cirrhosis four months later.
Our reaction to this situation seems to be that, not only does Michael do the right thing by Jeff in donating part of his liver, but that, by being reckless, Jeff does the wrong thing by Michael and this makes Michael's life being cut short worse than it would otherwise have been.
In analyzing Liver Transplant we can distinguish two features that contribute to the moral status of Michael's sacrifice in donating part of his liver to Jeff. On the one hand, there is the question of whether Michael acted appropriately as a moral agent. The answer to this question doesn't depend on what Jeff actually does next. What does matter is whether Michael himself is sensitive to all the moral reasons involved in this decision (including the expected benefit to Jeff at the time of transplant, the expected cost to Michael and any further considerations, such as special duties Michael may have to Jeff). The second is whether other people in this case are sensitive to the moral reasons that flow from this decision, and in particular the fact that, by deciding as he has, Michael has been harmed.
Despite the fact that it was morally justified, shortening Michael's life is a bad thing which, all else being equal, we would remove from the world if we could. Jeff's actions post-surgery appear to make this bad thing even worse, not because they make Michael's life any worse, but because they fail to realize the full extent of the benefits made possible by Michael's sacrifice. When performing his act of beneficence, Michael did the right thing because he judged that Jeff could expect to get much more than the ten years of additional life that Michael himself had sacrificed. He trusted Jeff to realize this full benefit from his sacrifice, making it, in other words, worthwhile. However, Jeff's actions post-surgery meant that he actually benefited by a lot less than Michael had lost. Jeff thus betrayed Michael's trust and thereby wronged him. By contrast, had Jeff lived a long life we would say that Michael's act of beneficence was worth it, while if Jeff did something even more valuable, for instance by going on to cure cancer, it would seem to have made Michael's sacrifice even more worthwhile (we would see it as morally fitting for Jeff to honor Michael's sacrifice in this way, and for others to help him do so).
Although our subsequent actions cannot prevent the harms that are involved in making a sacrifice, they can thus make this state better or worse all-things-considered by making these harms worthwhile. In this way, worthwhileness appears to alter the reasons we have for acting to varying degrees and can indicate a lack of concern for the interests of others.Footnote 3 This intuition about the moral worth of acts of beneficence, we think, is pervasive. Let's call it the Moral Worthwhileness Intuition (hereafter abbreviated ‘MWI’).
For anyone subscribing to the No Complainants Claim who also feels the force of MWI, there is pro tanto reason to prevent human extinction, and it seems like this reason could be articulated across a variety of moral theories. Even if it would not wrong any future people if ours was to be the last generation of humans, it still seems to wrong past people who had anticipated and made grave sacrifices for the benefit of future generations and the long-term future of our species. Only if future generations actually exist, and enjoy lives that are worth living, will these sacrifices be worthwhile.Footnote 4
3. Why worthwhileness matters
Yet, merely accepting the MWI still leaves important questions about the nature of our obligations to the past, and whether these give us reasons to ensure the survival of humanity. We neither wish, nor are able, to present a fully fledged theory of these obligations here. We do not wish to because we believe that the interpretation of the MWI should depend greatly on one's pre-existing moral beliefs, which we are not here presupposing, and we are not able to because doing so would surely be no small task and would distract from the purpose of this article: to show how accepting the MWI gives us reasons to care about human extinction.
However, one can appreciate the general form that such a theory might take by considering the fact that one who has made a sacrifice would reasonably object to another person acting in such a way as to make their sacrifice worthless. This is because making this sacrifice was morally supererogatory and done purely because of the benefits it would bring to others. Actually realizing these benefits, however, was not fully in the gift of the sacrificer and is thus left as unfinished business for others to complete: including both the person benefited and potentially other intermediaries between the sacrificer and the beneficiary. This unfinished business takes the form of additional obligations to act in ways that might otherwise have been purely supererogatory.
Let's spell this out more carefully:
Unfinished Business Account: If actor p reasonably judges performing a supererogatory act ϕ at great sacrifice to herself will enable beneficiary q to achieve a greater good, then failure to promote the good made possible by ϕ wrongs p.
Of course, this does not imply that this wrongdoing is always decisive, or even significant, in our moral considerations. I cannot enslave another simply by accepting some mild sacrifice whose benefits would depend greatly on what they chose to do. At the limit it is clearly not possible to oblige another person to accept a greater sacrifice than that which one originally accepted. So, for instance, while Michael could reasonably expect Jeff to refrain from drinking, and even to dedicate himself to some higher good, as a result of sacrificing part of his liver, he could not expect Jeff to undergo torture, even if this would ultimately produce some even greater good.
More substantially, it seems only reasonable that if our obligations to the past are to play a decisive role in our moral choices, then they should be at least broadly in line with our long-term interests and consistent with our conception of the good life, even if it's not what we ourselves would have chosen. For instance, we can easily imagine that Jeff looking after his liver is part of his conception of the good life even if he would much rather stare down the bottom of a bottle.
Plainly, Unfinished Business does not imply that any sacrifice by people in the past would ground a duty in me. Nor would this duty be unbounded, as we shall shortly discuss in more depth. While true that MWI generates in us pro tanto reason to realize the full value of sacrifices, the corresponding obligation is less demanding.
Another point of some contention for developing this theory is the question of whether we still have obligations to those who have made sacrifices even once they are dead. At least according to Parfit's conception of the No Complainants Claim, people can still be wronged by some act even though this act is not worse for them. Indeed, as Parfit writes, ‘some of the clearest cases [of this type] involve wronging people after they are dead’ (Reference Parfit2017a: 136). But there are narrower formulations, such as ‘an act cannot be wrong if it would be worse for no one’, which may not afford us this same conclusion.Footnote 5 We can never wrong our forebears, according to these formulations, because nothing we now do can make them better or worse off – after all, they are dead, so our argument does not go through. However, it is unclear just how substantial this limitation to our argument proves to be, given that many of us do believe, for example, that desecrating an ancient burial ground of some long lost civilization would wrong these dead people.
Nevertheless, this deserves some exploration. Some philosophers believe that a person's interests and rights cannot survive their death.Footnote 6 Nor can they be benefited or harmed after their death. If so, then how might a dead person be wronged by what we now do? Here, we assume the truth of Carl Wellman's notion of surviving duties (Reference Wellman1995: 156). As he writes, ‘Death destroys a person's capacity for agency and thereby destroys an essential qualification for being a moral right-holder. At the same time, death sometimes leaves the moral reasons intact so that, together with the qualifications of the surviving duty-bearer, these can ground a surviving duty’ (Wellman Reference Wellman1995: 156–7). Our claim is that, so far as we have a duty to realize the value of others’ sacrifices, these duties survive the death of the person who performed this sacrifice. Nor does their strength depreciate.
4. Objections and replies
This having been noted, let us now consider four objections that one might raise against our view.
4.1. Do all worthwhileness-undermining outcomes imply wrongdoing?
It may seem that our argument problematically implies that Michael can be wronged by blind luck, which is implausible. Suppose that, rather than drinking himself to death, Jeff is killed in a freak accident four months after receiving part of Michael's liver. According to the critic's interpretation, this makes the harm suffered by Michael less worthwhile, and thereby wrongs him. Analogously, if a solar storm destroys humanity, MWI implies that our forebears would be wronged by the Sun. This is absurd.
But this criticism misunderstands our argument. We claimed that Jeff has reason to realize the full worthwhileness of the harm accepted by Michael when donating part of his liver. More so, this harm is a bad thing that is made less worthwhile when Jeff dies still a young man. These are two separate claims. And, though the bad thing of cutting his life short is made worse however Jeff dies, Michael is only wronged if there is someone to be held responsible for a failure, which necessarily involves agency. So, it does not follow that Michael is wronged by blind luck. As we set it out above, what is wrong is not the simple fact that Michael's sacrifice has been made worthless, but that it was by refusing to complete the unfinished business of benefiting Jeff that Jeff wronged Michael in this way.
4.2. Did our ancestors really make sacrifices for the continued existence of humanity?
In the case of Liver Transplant, it seems that the person making a sacrifice needs to have some intention to do good in order for MWI to hold. Michael knows and intends that his donation be used to prolong Jeff's life. There is a direct connection between Michael's sacrifice and his goal of saving Jeff's life. This seems like an important feature that we should seek to incorporate into our theory.
By contrast, however, while it is true our ancestors suffered harms to help others, these sacrifices may not have been meant to benefit future generations, let alone the long-term future of humanity. People in the past who fought and died to abolish slavery, for example, may have done so to free the slaves who then existed and nothing more. Alternatively, it could be they failed to foresee that their actions would have any positive consequences in the future. Why then do we still owe it to these people to ensure the survival of our species?
This objection also misunderstands what we learn from Liver Transplant. There, we find MWI describes the harm to Michael as being even more worthwhile if Jeff were to cure cancer or eliminate global hunger. Our reaction to the case should not change if we stipulate that Michael never imagined this better world were possible as a result of him donating part of his liver; that, to his mind, he was trading ten years of life just so that Jeff could instead live another forty years. The moral reason Jeff has to realize the upper bound of value made possible by Michael's sacrifice does not appear to be constrained in some way by the mere fact that Michael has wildly underestimated the value of his organ donation.
If humanity goes extinct, then, although no further harms would be introduced into the world, people would have failed to respect the harms already suffered by their forebears and thus would have not have had due concern for the interest of these people. Just as MWI implies that Jeff going on to cure cancer makes Michael's sacrifice more worthwhile, it implies that prolonging human history, allowing our successors both to bring about and to experience more of the best things in life, makes the bad things encountered by our forebears when attempting to benefit humanity, though no less bad, more worthwhile. And, to be sure, the past is plagued by terrible things that individuals had to overcome for our benefit. Our ancestors fought for democracy, freed slaves, built the infrastructure that serves us, struggled through the Black Death and so forth.
We are thus very much in a similar position to Jeff when we are deciding whether to make humanity go extinct so as to live for a thousand years. Our world is a better one because our forebears abolished slavery and so forth, and this gives us reason to maximize the worthwhileness of the harms they suffered in pursuit of those good things. The strength of this reason is not weakened if those who sacrificed themselves for this goal lacked the imagination to foresee the far-reaching positive effects of their actions.
What does seem right about the criticism is this: the moral reasons that flow from the sacrifice of Michael's lifespan being cut short do not extend to the value created by a random stranger, Paul, on the other side of the planet. It would, of course, be very strange for us to claim that if Paul cured cancer, then Michael's sacrifice would be even more worthwhile. But this is not what we said in this article. On our view, because Paul does not benefit from Jeff receiving part of Michael's liver, he is not subject to the moral reasons which flow from that harm, and thereby cannot wrong Michael if he dies from cirrhosis in four months. However, we think there is an important difference between Paul in Liver Transplant and cases where people made sacrifices for the benefit of some quite general group like ‘future generations’, ‘the children of the oppressed’ or even simply ‘posterity’. In such cases we ourselves may well be beneficiaries from these sacrifices, but we can also legitimately be seen as trustees of the benefit that the sacrificer sought to bring about, and thus to face obligations as legitimate intermediaries between the sacrifices of the past and the good of future generations.
4.3. Aren't we being extorted by past people?
As we have already seen, our obligations to past people are not unlimited on the view we propose; far from it. Indeed, many may feel that while we do have some obligation to ensure the future of humanity, this will make no difference in the case with which we opened this article. In this case, they might argue, the loss of an additional 900 years of future life for us would be such a grave cost as to represent an overwhelming burden, so that no matter what sacrifices they endured, our obligations to past people to preserve humanity's future are far from decisive. However, that does not mean there are not still additional reasons for preventing humanity's extinction, and that they depend in part on how good humanity's future can be expected to be. In this article we are simply defending the notion that such reasons exist and accept that the question of their decisiveness cannot be settled without committing to a substantial moral theory.Footnote 7
However, even a less substantial view about the strength of our obligations to the past may go too far for some who feel that it is objectionable for past people to have placed any moral obligations on us, especially as we did not ask them to make this sacrifice. Consider that, in Liver Transplant, Jeff is no longer in charge. Michael has, in a very real sense, hijacked Jeff's life-plans. Worse still, Michael's donation and sacrifice were not required of him by morality – bear in mind, his act was supererogatory – and yet his ‘generous’ act, on our view, places Jeff under a duty which he previously wasn't under. If we further argue that the same obligations are being placed on present generations by the sacrifices of the past, isn't this tantamount to extortion or their robbing us of our own freedom to do as we choose within established moral limits?
This implication is true of our view. However, the correct comparison is not to robbery or extortion, but to deciding how much to leave in one's will.Footnote 8 There is nothing reprehensible about a decision that would leave our heirs much richer than they would have otherwise been, and possibly even much richer than we are. Jeff is far richer after having inherited forty more years and some unfinished business of Michael's than if Michael had refused to donate part of his liver. Similarly, those now alive are far richer than their forebears, given how much we benefited from diseases being cured and wars fought, even if some of these benefits are not ours to keep but must instead be put towards improving the lot of future people. Indeed, this strikes us as no more oppressive than leaving behind a trust fund that can be used only for the purpose of attending college.
4.4. Do our obligations to the past outweigh concern for bodily integrity?
This section considers one last objection.
Suppose I previously made a promise to my grandmother to carry on the family. So far as one finds purchase in surviving duties, it seems I have a duty to discharge this obligation even if either my grandmother has died or I have since changed my mind and wish I had never made the promise. Being held accountable is simply part of what it means to be a morally responsible agent. But, Elizabeth Finneron-Burns (Reference Finneron-Burns2017: 340–1) claims, it seems unlikely that keeping a promise to my grandmother to carry on the family would be much weightier than my interest in making decisions about my own body. That is to say, it would be permissible for us to break this promise, given its extremely intimate nature, and thereby wrong her. Analogously, even if we were to wrong our forebears by allowing humanity to go harmlessly extinct, it may be that respecting the bodily integrity of those currently alive should always be decisive in permitting such wrongdoing.
We are less sure about this than Finneron-Burns. She says that my promise to my grandmother should not force me to have a child, and that may seem correct, but there surely are obligations that could require this, even according to theories that accept the No Complainants Claim; for instance, if my having a child were the only way to free somebody from an even greater loss of bodily integrity or prevent a terrible catastrophe. The question is whether our duty to our forebears could ever require this.
Our critic may respond that, if anything, our obligation to our ancestors resembles, not a promise, let alone some stronger obligation to prevent a terrible catastrophe, but a grandmother's dying wish that I have a child. In this case, we agree with Finneron-Burns that, while this dying wish should factor into my decision, it is permissible for me to refuse the tremendous responsibility of procreation. However, this ignores an important feature of our situation; it is not that past people merely wished humankind would survive; they made great sacrifices towards securing this better world for us.
Let's redescribe the circumstances of her dying wish. Suppose my grandmother had foregone the best things in life so that her lineage might continue and prosper. When the war broke out, she endured extreme torture to protect the nest egg she had saved for my potential child's college education. Because of this, let us assume that her life was, on balance, hardly worth living. If I then decide not to have children merely so that I could squander the trust fund she set aside for them, would this not have wronged her by failing to respect the sacrifices she had made?
Of course, if there were others willing to carry on my grandmother's family line, then it need not fall to me to have children in response to her sacrifices. However, if I am genuinely her last hope for seeing this wish fulfilled, then these considerations may well weigh heavily upon me. There are certainly cases in which people have felt morally obliged to undergo considerable harms to continue their lineage, culture, language or way of life out of respect to their forebears, and people who act in this way do not seem to us to be making any moral mistake. Thus, some of us will no longer be convinced that bodily integrity inevitably overwhelms all obligations to prevent wronging another person. This is also our position. But others will not be moved. For them, it is no doubt regrettable that my decision wrongs my grandmother, but it is nonetheless morally permissible for me to do so as this preserves my bodily integrity. Yet, as far as we are aware, there is no straightforward moral theory that will always respect these people's views unless it includes a deontological side constraint that says ‘when it comes to having children, one is never morally required to act against one's will’.
Is such a side constraint tenable? We think not. If my bodily integrity trumps the wrongs I may do to that end, then it seems permissible for me to create a life not worth living. This poor soul I create would suffer endlessly, and therefore my act wrongs him. But, by the critic's own light, this wrongdoing simply does not tell against my interest in bodily integrity in enough moral force. In response, it could be said that, while the wrong of creating a life not worth living does outweigh my interest in bodily integrity, the wrongs done to past people don't. However, it is entirely unclear why we should grant this proposed asymmetry between the types of wrongs done to dead and possible people; that is, apart from that we wish to avoid a moral duty to create happy people. This idea has considerable psychological force; it is hardly shocking that some are willing to accept robustly counterintuitive implications to rescue the neutrality of adding happy people on their moral theory (cf. McMahan Reference McMahan1981). But, to our minds, this asymmetry cannot survive upon closer inspection; not only is it wildly ad hoc, but allowing any number of wrongs to dead people is simply too high a price to pay.Footnote 9
Yet, at most such an obligation would apply only in extreme cases, where procreation was absolutely necessary for humanity's survival and nobody else was willing to undertake this action. Furthermore, depending on our choice of moral theory, it may be that even under these conditions some may see the harm of having children for moral reasons, rather than out of personal preference, as unacceptably great. However, we do not see it as an objectionable aspect of what we have here argued that on other moral theories our obligations to the past may extend to requiring us to have children in order to preserve the future of our species.
5. Conclusion
This article demonstrated that views which endorse the No Complainants Claim should describe the decision to permanently end human history as wrong if it wrongs our forebears. This is because, as we argued, our extinction could make their sacrifices less morally worthwhile, giving us moral reason to avoid it.
This simple idea, that humanity's survival and achievement of great goods can make the sacrifices of our forebears worthwhile, could be adopted by many reasonable moral theories. But MWI plays a particularly special role for the No Complainants views because it offers a plausible way to dodge the counterintuitive implication that choosing to go extinct is not wrong. It also seems to buttress a justification for working to ensure the survival of humanity that Parfit offered at the end of his final book:
Some of our successors might live lives and create worlds that, though failing to justify past suffering, would have given us all, including those who suffered most, reasons to be glad that the Universe exists. (Parfit Reference Parfit2017b: 436–7)Footnote 10
