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There are many ways to critique this argument, of course, but I wish to focus on a particularly radical kind of response I encountered recently. During the 2018 meeting of the Society for Social and Conceptual Issues in Astrobiology (SSoCIA), an organization devoted to discussion of the many broader issues surrounding astrobiology and space exploration, there was a panel discussion on the ethics of human colonization. When the bet hedging argument came up, some scholars countered that we should not subject other worlds to our reckless environmental practices, period. They felt that, until and unless humans can demonstrate an ability to live in harmony with our environment, we deserve extinction. This claim is highly ambiguous in at least two important ways. First, it’s very unclear what exactly would constitute success in “living in harmony with the environment,” which risks creating an impossible standard. Second, it’s very unclear precisely in what sense all of humanity could deserve extinction, since it is hardly the case we have, each and every one of us, committed a capital offense. Whatever the precise details, I will label the claim that humans should go be allowed to go extinct for our ecological sins eco-nihilism.

It is difficult to find explicit defenses of this position in the literature, though many have at least flirted with variations on the idea. Deep ecologists have been arguing for some time (see Drengson 1995) that constituents of the natural world have moral value on a par with human beings, even humanity as a whole. This naturally leads to the thought experiment Alan Weisman conducts in his influential book The World Without Us (2008) where he considers the ways the Earth and its inhabitants would be better off without its human population. Adam Morton’s Should We Colonize Other Planets? (2018) reflects the increasingly common sense of ecological pessimism by arguing that humans are doomed in the long run anyway, and thus it’s best for all concerned if we simply resign ourselves to extinction1. Not surprisingly, this combination of extreme pessimism about our future and guilt concerning the human role in bringing it about can produce some truly extreme positions. Witness the Voluntary Extinction Movement (Jarvis 1994), which takes the position that humans are morally obligated to stop reproducing altogether. Such ideas also seem to have influenced the terrorist group Earth First! I certainly don’t mean to suggest that such radical ideas are representative of those who oppose human colonization, but I do think the pessimism and guilt driving these extreme views have an unappreciated influence that cries out for critique.

Human extinction is now tacitly accepted as the proper and moral solution to environmental problems. Whether in the writings of the Unabomber or Al Gore, humans are identified as the primary danger to the ecosystem. Both agree with the self-proclaimed "deep ecologists" that all ecological problems would disappear along with our species. This is the late 20th century's standard ecological paradigm, taught in every public elementary school, Captain Planet episode and graduate social-science course. "Everything was fine in the forest before the evil humans came with their 'technology' and their 'culture', and everything will be fine again if humans all catch Ebola or Marburg and die. The deer will scamper happily through the forest as their guts are torn out by the happy wolves, until they are all covered quietly by the happy continental ice sheets..." .... or maybe the Unabomber/Gore types didn't think quite that far ahead.

The human species is not the source of ecological Original Sin. For any real "deep ecology" theory, the long-term survival of life requires an intelligent species to develop the necessary technologies. Contrary to myth, humans have benefited the ecosystem; already we may well have prevented the Final Ice Age.

Human extinction in the next few centuries could reduce the number of future generations by thousands or more. We take extraordinary measures to protect some endangered species from extinction. It might be reasonable to take extraordinary measures to protect humanity from the same.19

[FOOTNOTE]

The more environmentally conscious have all had the thought, whether they admit it or not: what would the world be like if there were no humans here?

That question is at the heart of a wonderful, relevatory book by Alan Weisman titled The World Without Us.

Yet how should rational moral agents behave if - hypothetically - some variant of Benatar's diagnosis as distinct from policy prescription was correct?

In an era of biotechnology and unnatural selection, an alternative to anti-natalism is the world-wide adoption of genetically preprogrammed well-being. For there needn't be selection pressure against gradients of lifelong adaptive bliss - i.e. a radical recalibration of the hedonic treadmill. The only way to eradicate the biological substrates of unpleasantness - and thereby prevent the harm of Darwinian existence - is not vainly to champion life's eradication, but instead to ensure that sentient life is inherently blissful. More specifically, the impending reproductive revolution of designer babies is likely to witness intense selection pressure against the harmfulness-promoting adaptations that increased the inclusive fitness of our genes in the ancestral environment of adaptation. If we use biotechnology wisely, then gradients of genetically preprogrammed well-being can make all sentient life subjectively rewarding - indeed wonderful beyond the human imagination. So in common with "positive" utilitarians, the "negative" utilitarian would do better to argue for genetically preprogrammed superhappiness.

It is also possible to take issue with the claim that the environment would be that much better off without humans or that the effect of humanity on the environment is so awful that we ought to die off. Nature can be sickeningly cruel without any human intervention. Animals can cause as much deforestation and environmental degradation as humanity does at the local scale. Plants, as well as humans, have caused climate catastrophes by changing the composition of the atmosphere.

There were two dozen mass extinction events before the evolution of modern humans. One of these, the Permian–Triassic extinction event, saw 96% of all marine and 70% of all land-dwelling vertebrate life die. The famous Cretaceous extinction event featured the death of the dinosaurs and almost every land animal that weighed more than 55 pounds as the result of a giant asteroid hitting the earth, as they often have done and will do again. Humans have yet to do anything with nearly the kind of impact on the environment as these random events had.

These environmentally-concerned anti-natalists believe that a world without humans, or with significantly fewer of them, would eventually revert to a pollution-free paradise with abundant natural resources. As one human extinction proponent put it just last month in a letter to his local paper, “In approximately 20,000 years after human extinction, this magnificent resistant biosphere will return to its perfection.” If humanity fails to reduce its numbers, extinction proponents fear resource shortages and environmental catastrophe. “How could anybody,” an official Vhemt member, Gwynn Mackellen, wondered aloud to the Guardian, “produce a new human when the effects of humans are very obvious, I feel, and the situation is getting worse.”

These extinction advocates, however, have misunderstood the evidence about population growth’s impact on the planet and its resources. The late University of Maryland economist Julian Simon rejected the idea of overpopulation as a problem. He believed that, on the contrary, more people in the world means more people to solve problems, and less resource scarcity. “There is no physical or economic reason,” he wrote, “why human resourcefulness and enterprise cannot forever continue to respond to impending shortages and existing problems with new expedients that, after an adjustment period, leave us better off than before the problem arose.”

But there’s something far more disturbing to me about May’s piece. He thinks that the harm human beings inflict on the world cannot be stopped. It is inevitable. So long as we are here, we will continue to engage in these practices, so the question is whether or not we should be here. This is a little weird to me: To think that “stopping human beings from existing at all” is somehow more of a plausible option than “stopping factory farming and human-made climate change” means an extreme form of pessimism about the possibilities for changing our actions. As he says, the elimination of these wrongs “would likely require the elimination of the species.”

Respectfully, what the fuck? May says this as if it’s a given—there’s not a shred of argumentation offered. He thinks we’ll just nod and agree that it’s impossible to stop climate change, factory farming, and the destruction of ecosystems, that they will only come to an end if we commit civilizational suicide. I’m sorry, but that’s not the sort of proposition you can just state as an uncontroversial fact. Especially because these are all extremely recent phenomena—modern-day industrial animal farming began within the lifetimes of presently-living people. Human beings have been around for 200,000 years and it was only in the last few hundred that we set ourselves on the course toward destroying the earth and the mass destruction of other species’ habitats. Since we lived for many, many millennia without doing any of these things, why would we conclude that it’s totally impossible for us to live sustainably ever again, even with greater knowledge about how to do so than any previous generation of humans ever had?

As a barometer of the depravity of atheistic modernism and of the Gaia cult it has spawned, this New York Times essay by Clemson University philosophy professor Todd May is hard to beat. May asks the question: Given the hypothetical “increasing predations of climate change,” would human extinction be a tragedy?

To get a bead on this question, let me distinguish it from a couple of other related questions. I’m not asking whether the experience of humans coming to an end would be a bad thing. (In these pages, Samuel Scheffler has given us an important reason to think that it would be.) I am also not asking whether human beings as a species deserve to die out. That is an important question, but would involve different considerations. Those questions, and others like them, need to be addressed if we are to come to a full moral assessment of the prospect of our demise. Yet what I am asking here is simply whether it would be a tragedy if the planet no longer contained human beings. And the answer I am going to give might seem puzzling at first. I want to suggest, at least tentatively, both that it would be a tragedy and that it might just be a good thing.

I’ve been surprised to learn recently that so many people I know in the effective altruism community believe there is more total suffering than happiness in the lives of wild animals. Brian Tomasik appears to be the main current proponent of this view, developing the work done by economist Yew-Kwang Ng in the 90s. Tomasik has taken his concerns with wild animal suffering (WAS) to its logical limit, arguing we should consider destroying ecosytems so that fewer animals exist. This cuts against the popular intuition, frequently promoted by nature documentaries, that wild animals live enjoyable, if somewhat barbaric, lives and are best left to their own devices. As the number of animals in the wild is so vast, WAS is therefore potentially of huge moral importance. Concerned that I had overlooked the area, I investigated. After some consideration, I think the arguments in favour of there being net WAS are unconvincing. I decided to write this essay to explain why others should be similarly unconvinced. I’ve reconstructed Tomasik’s argument below and then set out five objections. For readers impatient for the punchline, the thrust of my argument is 1) the case for net wild animal is highly selective, relying on imagining obviously bad aspects of animals’ lives, such as being eaten alive, rather than accounting for all their positive and negative experiences and 2) it requires immense speculation about how good or bad animals’ experiences are (e.g. how many hours of eating grass is equivalent to 5 minutes of being eaten alive? how many unhappy ants is worth one happy lion?). We should be wary of overstepping our epistemic limits and engaging in careless anthropomorphism. I, briefly, present my own moral response: certain, targeted interventions may reduce WAS but habitat destruction is unlikely to be justified. I note WAS is unlikely to be a particularly cost-effective way of reducing suffering. To be clear, I do not claim the lives of wild animals are net positive or negative overall. I do not think I (or anyone else) can show that. Nor do I deny there is wild animal suffering. There clearly is. My point is that Tomasik overstates the case for net wild animal suffering and understates the difficult of making interpersonal and interspecies comparisons of happiness.

It’s possible technological improvements will make radical interventions in wild animal welfare feasible. Artificially intelligent flying drones could replace and extend the activities park rangers have typically filled in animal reserves, for instance delivering medication via dart guns to animals that would cure misery-causing intestinal worms or provide vaccinations. Further, if we believe the zebra’s experience of being killed in truly terrible, we could also fill such zebras with amphetamines or opiates prior to letting the lions kill it. In the (far) future, once many other problems have been solved, this may be a cost-effective way to increase happiness compared to the alternatives.

1.3: Future agents could later decide not to colonize space (option value)

We are often uncertain about what the right thing to do is. If we can defer the decision to someone wiser than ourselves, this is generally a good call. We can also defer across time: we can keep our options open for now, and hope our descendants will be able to make better decisions. This option value may give us a reason to prefer to keep our options open.

If humans become extinct, wild animal suffering will continue indefinitely on earth (unless all other animals go extinct as well, which is unlikely but possible). Wild animals’ lives are likely not worth living, so this would be bad, but it’s not the worst thing that could happen.

Preventing human extinction obviously means that humans will continue to exist, but this direct effect is trivial compared to the effects described below.

Arguments on Why Preventing Human Extinction May Be Good or Bad

Bad: Humans make wild animal suffering worse on earth

First, the big picture. We've got hundreds of millions of years left on Earth if nothing very bad happens first. If we can keep our civilization going, we've got much, much more time ahead of us in space colonization. But humanity may be Earth-originating life's only shot at colonization. Given the apparent lack of other intelligent life out there (the Fermi paradox), the fate of life in the universe may well be in our hands. I'd say everything else we could concern ourselves with simply pales in comparison to the fate of life in the universe! Given the many non-trivial threats to our survival we currently face, I recommend focusing on protecting our survival until we drive the risk of our extinction down to right around zero.

Political Ideologies

We should be more pessimistic when we review how nonhuman animals have fared in the last century. At present around 50 billion animals are raised and killed each year to feed humanity. (Many million animals are used for clothing, product testing, research, and entertainment, but their numbers are insignificant by comparison.) Since World War 2, with the invention of "factory farming," farm animals’ welfare has significantly deteriorated, as they now live in conditions that frustrate their most basic instincts (Singer, 2002, chapter 3). At the same time, we’re probably the only animal on Earth that routinely demonstrates compassion for other species. Such compassion is nearly universal in developed countries but we usually know too little, too late, for deeply ingrained habits, such as diets, to change. If improvements in other public morals were possible without any significant biological change in human nature, then the same should be true for our treatment of nonhuman animals, though it will take some time.

Even without any change in public morals, it seems unlikely we will continue to use animals for very long – at least, nowhere near 50 billion per year. Our most brutal use of animals results not from sadism but from old appetites now satisfied with inefficient technologies that have not fundamentally changed in 10,000 years. Ours is the first century where newer technologies -- plant or in vitro meats, or meat from brainless animals -- could satisfy human appetites for meat more efficiently and safely (Edelman et al, 2005). As these technologies mature and become cheaper, they will likely replace conventional meat. If the use of sentient animals survives much beyond this century, we should be very surprised. This thought is a cure for misanthropy. As long as most humans in the future don't use sentient animals, the vast number of good lives we can create would outweigh any sins humanity has committed or is likely to commit. Even if it takes a century for animal farming to be replaced by vegetarianism (or in vitro meats or brainless farm animals), the century of factory farming would represent around 10^12 miserable life-years. That is one-billionth of the 10^21 animal life-years humanity could save by protecting Earth from asteroids for a billion years. The century of industrialized animal use would thus be the equivalent of a terrible pain that lasts one second in an otherwise happy 100-year life. To accept human extinction now would be like committing suicide to end an unpleasant itch. If human life is extinguished, all known animal life will be extinguished when the Sun enters its Red Giant phase, if not earlier. Despite its current mistreatment of other animals, humanity is the animal kingdom’s best long-term hope for survival.

In contrast, I assume here that moral value is a function of both the quality and number of lives in a history.[3] This view is consistent with most people’s intuition about extinction (that it’s bad) and with moral theories under which life is considered a benefit to those who have it, or under which life is a necessary condition for producing things of value (Broome, 2004; Hare, 1993; Holtug 2001, Ng, 1989; Parfit 1984; Sikora, 1978). For instance, some moral theories value things like experiences, satisfied preferences, achievements, friendships, or virtuous acts, which take place only in lives. On this view, an early death is bad (at least in part) because it cuts short the number of these valuable things. Similarly, on this view, an early extinction is bad (at least in part) because it cuts short the number of these valuable things. I think this view is plausible and think our best reasons for believing an early death is bad are our best reasons for believing an early extinction is bad. But such a view is controversial and I will not settle the controversy here. I start from the premise that we ought to increase moral value by increasing both the quality and number of lives throughout history. I also take it, following Singer (2002), this maxim applies to all sentient beings capable of positive subjective feelings. Life’s prospects The human population is now 6 billion (6 x 109). There are perhaps another trillion (1012) sentient animals on Earth, maybe a few orders more, depending on where sentience begins and ends in the animal kingdom (Gaston, Blackburn, and Goldewijk, 2003; Gaston and Evans, 2004). Animal life has existed on Earth for around 500 million years. Barring a dramatic intervention, all animal life on Earth will die in the next several billion years. Earth is located in a field of thousands of asteroids and comets. 65 million years ago, an asteroid 10 kilometers in size hit the Yucatan , creating clouds of dust and smoke that blocked sunlight for months, probably causing the extinction of 90% of animals, including dinosaurs. A 100 km impact, capable of extinguishing all animal life on Earth, is probable within a billion years (Morrison et al., 2002). If an asteroid does not extinguish all animal life, the Sun will. In one billion years, the Sun will begin its Red Giant stage, increasing in size and temperature. Within six billion years, the Sun will have evaporated all of Earth’s water, and terrestrial temperatures will reach 1000 degrees -- much too hot for amino acid-based life to persist. If, somehow, life were to survive these changes, it will die in 7 billion years when the Sun forms a planetary nebula that irradiates Earth (Sackmann, Boothroyd, Kraemer, 1993; Ward and Brownlee, 2002). Earth is a dangerous place and animal life here has dim prospects. If there are 1012 sentient animals on Earth, only 10^21 life-years remain. The only hope for terrestrial sentience surviving well beyond this limit is that some force will deflect large asteroids before they collide with Earth, giving sentients another billion or more years of life (Gritzner and Kahle, 2004); and/or terrestrial sentients will colonize other solar systems, giving sentients up to another 100 trillion years of life until all stars begin to stop shining (Adams and Laughlin, 1997). Life might survive even longer if it exploits non-stellar energy sources. But it is hard to imagine how life could survive beyond the decay of nuclear matter expected in 1032 to 1041 years (Adams and Laughlin, 1997). This may be the upper limit on the future of sentience.[4] Deflecting asteroids and colonizing space could delay the extinction of Earth-originating sentience from 109 to 10^41 years. Assuming an average population of one trillion sentients is maintained (which is a conservative assumption under colonization[5]), these interventions would create between 1021 and 1053 life-years. At present on Earth, only a human civilization would be remotely capable of carrying out such projects. If humanity survives the next few centuries, it’s likely we will develop technologies needed for at least one of these projects. We may already possess the technologies needed to deflect asteroids (Gritzner and Kahle, 2004; Urias et al., 1996). And in the next few centuries, we’re likely to develop technologies that allow colonization. We will be strongly motivated by self-interest to colonize space, as asteroids and planets have valuable resources to mine, and as our survival ultimately requires relocating to another solar system (Kargel, 1994; Lewis, 1996). Extinction risks Being capable of preserving sentient life for another 10^41 years makes human survival important. There may be nothing more important. If the human species is extinguished, all known sentience and certainly all Earth-originating sentience will be extinguished within a few billion years. We ought then pay more attention to what Bostrom (2002) has called “existential risks” -- risks “where an adverse outcome would either annihilate Earth-originating intelligent life or permanently and drastically curtail its potential.”

Yet how should rational moral agents behave if - hypothetically - some variant of Benatar's diagnosis as distinct from policy prescription was correct?

In an era of biotechnology and unnatural selection, an alternative to anti-natalism is the world-wide adoption of genetically preprogrammed well-being. For there needn't be selection pressure against gradients of lifelong adaptive bliss - i.e. a radical recalibration of the hedonic treadmill. The only way to eradicate the biological substrates of unpleasantness - and thereby prevent the harm of Darwinian existence - is not vainly to champion life's eradication, but instead to ensure that sentient life is inherently blissful. More specifically, the impending reproductive revolution of designer babies is likely to witness intense selection pressure against the harmfulness-promoting adaptations that increased the inclusive fitness of our genes in the ancestral environment of adaptation. If we use biotechnology wisely, then gradients of genetically preprogrammed well-being can make all sentient life subjectively rewarding - indeed wonderful beyond the human imagination. So in common with "positive" utilitarians, the "negative" utilitarian would do better to argue for genetically preprogrammed superhappiness.

When a friend of the American composer John Cage asked, "Don't you think there's too much suffering in the world?", Cage answered, “No, I think there's just the right amount”. Few ethicists openly express such Zen-like equanimity at the suffering of other sentient beings; but until recently all ecologists shared Richard Dawkins' assumption of its inevitability. However, the living world is on the brink of a technical and ethical revolution - and a major evolutionary transition in the development of life. Humanity will shortly be able to decide the optimal level of suffering both for members of our own species and across the tree of life itself. Not least, CRISPR-driven gene drives can cheaply, rapidly and dramatically reduce suffering in all species of sexually reproducing organism.

Until 21st century biotechnology, the sheer cost, computational complexity and technical obstacles to tackling suffering in free-living non-human animals seemed daunting to anyone who cared about nonhumans. A pan-species welfare state was inconceivable. Cross-species fertility-regulation via immunocontraception, neurochipping, GPS-tracking and monitoring, and rudimentary healthcare services would be prohibitively costly even for large, long-lived vertebrates in human wildlife parks. How could we possibly hope to tackle suffering in marine ecosystems or the Amazon rainforest, short of invoking molecular nanotechnology and what critics would call Drexlerian sci-fi? Actively helping free-living non-humans in an era when millions of people still lack adequate nutrition and healthcare, and when humans still systematically hurt, harm and kill billions of sentient beings in factory-farms and slaughterhouses, has made such a project seem sociologically fanciful as well. Evolution didn't design Homo sapiens to be impartially altruistic.

The number of wild animals vastly exceeds that of animals on factory farms, in laboratories, or kept as pets. Therefore, animal advocates should consider focusing their efforts to raise concern about the suffering that occurs in the natural environment. While in theory this could involve trying directly to engineer more humane ecological systems, in practice I think activists should concentrate on promoting the meme of caring about wild animals to other activists, academics, and other sympathetic groups. The massive amount of suffering occurring now in nature is indeed tragic, but it pales by comparison to the scale of good or harm that our descendants -- with advanced technological capability -- might effect. I fear, for instance, that future humans may undertake terraforming, directed panspermia, or sentient simulations without giving much thought to the consequences for wild animals. Our #1 priority should be to ensure that future human intelligence is used to prevent wild-animal suffering, rather than to multiply it.