Discussions of ecological futures struggle to see beyond the myopic horizon established by Big Tech billionaires. Proposed solutions to the planetary crisis, be they solar panels or space colonisation, are framed as technical fixes rather than deeper inquiries about what kinds of worlds are worth sustaining and why.

PETER WOLFENDALE When we talk about what’s at stake in ecological risk, there are two extremes toward which people tend. Some think principally in terms of maintaining ecological stability or natural equilibrium, while others think in terms of optimising the amount of value in the world, whether that is wellbeing, happiness, pleasure, et cetera. These perspectives often converge in their proximate goals: both may advocate for, say, animal welfare. But their long-term consequences drastically diverge.

The idea that the stability of nature involves a certain amount of suffering, of nature “red in tooth and claw”, is beyond the pale for those who have a more utilitarian conception of the world. Some even advocate for the complete elimination of predation, or otherwise eliminating species whose wretched lives make a net negative contribution to the calculus of value. The idea that nature ought to be redesigned and rationalised understandably horrifies those determined to preserve it. This mutual horror signals a philosophical impasse.

My own view is that what’s principally at risk here is freedom: not just the existence, but the flourishing of free beings – humans, more or less. This can seem quite callous, treating nature as a mere resource or blank canvas with which to do what we will. But I think there is a deeper story to be told about the relationship between freedom and nature here. One first has to acknowledge that value is what motivates choice, and only really exists if there are beings confronted with such choices. This implies that what is most valuable is not just the presence, but the proliferation of choice. Freedom is the only thing that gives itself value, but it also needs things outside itself to give value to. It is both constitutively embedded in nature and productively constrained by it. It can’t close itself off.

One surprising consequence of this view is that if freedom is what’s fundamentally important, then the voluntary extinction of our species must be permissible. We must be free to choose our own ending, either individually or collectively. Some of those in favour of the ecological stability perspective are perfectly fine with voluntary extinction, as long as nature persists, whereas those on the utilitarian, long-termist side argue that humans ceasing to exist would be the worst thing that could possibly happen. My position is that voluntary extinction would be a tragedy, but not a crime, because freedom cannot be obliged to exist.

THOMAS MOYNIHAN On this question of ecology, I think the political scientist Daniel Zimmer has a good orienting conception of the varying outlooks, which updates the traditional political compass of leftwing and rightwing that emerged from the French Revolution. He claims that what’s at stake in contemporary debates about nature and its future can be mapped on what he calls “upwing” and “downwing” stances. Upwingers want to intensify intelligence, technological disruption and the reorganisation of nature, whereas downwingers identify with pre-existing homeostasis and natural equilibrium. So, transcendence versus immersion. At the far-upwing, you have these techno-utopian visions of rearranging star systems and galactic filaments; at the far downwing, you find the voluntary extinction movement looking to return the world to some kind of pre-existing natural balance. I think it’s a brilliant formulation of current tensions in philosophy and politics in general: between those who want to accelerate and intensify tech’s transformation of the world, and those who are instinctively suspicious of technology as such.

I agree with you on this question of maintaining the centrality of freedom being voluntary above all else. A quote from your essay “Beyond Survival” resonated with me: “The only system that can be generally committed to survival for its own sake is one that can choose otherwise”. The idea of the “voluntary” here is distinct from that of the voluntary human extinction movement, which I find frankly upsetting, or radical posthumanists, such as the philosopher Patricia MacCormack, who think of human extinction as a form of atonement for the human-led disruption of ecosystems. My critique of that positioning is that it assumes the human species is the only species that possesses the ability to disrupt its environment, which is historically untrue. The evolution of photosynthesis pumped tonnes of oxygen into the atmosphere, plausibly causing a mass extinction. What makes humans different is that we’re aware of what we’re doing, which is what makes it an ethical question. Yet to think that we’re the only species that has introduced this massive atmospheric disruption is to reintroduce another form of metaphysical exceptionalism, another form of anthropocentrism. In the Enlightenment view, the human is the protagonist of everything, the pinnacle of creation, the bearer of all good. The argument being made is the reformulation of this worldview in the negative, where instead of being the protagonist, humans are now the antagonist. In my book X-Risk, I suggest that the apotheosis of the Enlightenment articulation of the “is-ought” problem is the idea of extinction. In philosophy and ethics, the “is-ought” problem refers to the realisation, which began sometime during the late Middle Ages, that nature does not, and should not, dictate what we value. Or put differently, just because something exists doesn’t mean it is inherently good. This realisation blossomed, in politics, into progressive questioning of power and perceived “natural” hierarchies. But I argue that, in science and natural philosophy, it blossomed into awareness that, if existence isn’t independently good, then goodness itself can cease to exist. This led to awareness that not just the human species, but also any type of human project, can go extinct. In other words, the independent universe will not independently champion the projects, goals and ends that humanity finds desirable. If humans, or moral agents, are the only conjurers of value in the world, then the whole enterprise of valuing obligates us towards survival.

Peter Wolfendale is an independent philosopher, working on metaphysics, computation, and theory of value. He is the author of The Revenge of Reason (2025). Thomas Moynihan is a writer and historian of ideas and the author of X-Risk: How Humanity Discovered Its Own Extinction (2020). In this discussion, Peter and Thomas discuss how the topic of existential risk shapes contemporary philosophy, the ethical limits of human-centric thinking and the assumptions that structure visions of survival, value and futurity.

Patricia MacCormack argues that voluntary human extinction would be a radical form of ethical atonement for the harm humans have caused to other beings and the planet. She concludes that the death of the human species might be the most “life-affirming” outcome for the rest of the living world.

PW I share your intuition that there is something important about us being in the world as creatures that can recognise and create value. Without us, there is something essential lost. But making that notion coherent requires more conceptual work than is involved in the standard utilitarian take.

My approach is to distinguish between two different kinds of value: Beauty and Rightness. Rightness is a matter of obligation – what is practically necessary, what we must do in order for any pursuit of value to be possible at all. While Beauty concerns excellence – what is practically contingent, what is better than what’s merely required. Ethical imperatives trump aesthetic motivations. Rightness always overrides Beauty, but Beauty is the aim of Rightness. Ethical constraints are not unconditionally valuable, but the conditions that make possible the pursuit of unconditional value.

Utilitarians collapse these two types of value into a singular notion of Goodness. The result is mandatory excellence: that what you should do is whatever produces the best possible overall state of the universe. I think that the very idea of a “best” possible universe is fundamentally incoherent, in much the same way the idea of a “best” possible poem is incoherent. When you look at value through the lens of aesthetics, the very notion of perfection makes a lot less sense.

Fiction is actually one of the few domains in which we’re used to thinking about the value of worlds as a whole. We think of fictive universes in aesthetic terms, to the point where you can reasonably ask, “Which universe would you rather live in? Tolkien’s Middle Earth? Banks’s Culture? Et cetera…” We might want universes that contain drama and challenge, but there’s no real procedure for coming up with an optimal answer to what the “best” such universe is. Once we separate out these two notions – the ethical Rightness of actions versus the unconditional Beauty of things – we see that it can be true both that the presence of freedom in the universe is aesthetically paramount, and that the right of this freedom to erase itself is ethically inviolate.

TM As you’ve argued elsewhere, the idea of some optimal state can suborn our better judgment, making us do unethical things to arrive at this best-of-all-possible worlds. Nevertheless, from many perspectives, the universe appears to be in a suboptimal state; it seems primarily sterile and monotonous relative to what it could be, given the amount of energy that’s in circulation. Yet, with your idea about maintaining a difference between Beauty and Rightness, can keep the intuition that a better universe could be possible without turning that into an obligation.

In X-Risk, I proposed the discovery of human extinction as a question of species-level maturity. We have to be careful with the blanket assumption that, as an individual learns and accumulates wisdom over time, so does the species itself. However, this is true to some degree. Anthropologists call it “cumulative culture”. Conceiving of our own extinction was a step towards assuming responsibility at the species level. There was a time when humans weren’t thinking at this level, and a time after which they began to. That’s a step forwards.

Jonathan Schell, in his amazing essays on the ethics of thermonuclear war, spoke about what he called the “Second Death”. In our personal lives, somewhere between age five and seven, we begin to come to terms with our own death, the idea that the universe may continue without us. We can call this the “First Death”, the first mortality we encounter. As a species, several generations ago, we started to think of the death of the species itself: Schell’s “Second Death”. But there are more deaths radiating outwards, each of which has its own history of discovery, of how we came to acknowledge and apprehend it. The Third Death is the expiration of the biosphere, of all the shared lineage of life on Earth that traces back to a singular origin event, which, unless life somehow migrates elsewhere, is set to happen in a number of billions of years as our aging sun expands. Beyond that, there’s a Fourth Death, which is that of the universe itself. Based on current understandings of thermodynamics and the universe’s expansion, it appears that there will be a time when nothing interesting can happen in the universe anymore. But this, paradoxically, is salutary. The fact that the universe will die means there is a weight to every action we take. If there is a finitude of future actions, choosing one over the other becomes consequential, even in the tiniest sense: your choice uses energy from this enormous but finite endowment. You can reverse actions, of course, but this itself expends energy. So, the impermanence of the universe vouchsafes the permanence of action. Existence’s mortality secures decision’s immortality.

One thing that makes me slightly suspicious of the idea that we should be filling the universe with as much value as possible is that it looks like a prescriptive transposition of an ancient metaphysical assumption that’s been called the Principle of Plenitude. That’s an opaque sentence, so let me unpack it.

The Principle of Plenitude is one of the most deeply held beliefs in traditional Western metaphysics. It’s basically the claim that the universe is, at any one time or across time, as full as possible, of as many possibilities as it can be. This is based on lack of acknowledgement or ignorance concerning the is-ought distinction, because we think of waste and gratuity as in some sense bad. So, from the beginnings of Western philosophy well into the Enlightenment, scientists and philosophers assumed that if it would be morally unconscionable for something possible not to exist, then it must also be factually false that it does not exist (or, that it can cease to exist; hence, no awareness of extinction). You arrive at this idea of the universe being really full of everything, which is, in and of itself good. The collapse of the Principle of Plenitude, which took place during the 1800s, was the discovery of our own extinction. Without Plenitude, things can exit existence permanently, never to return.

But with the collapse of Plenitude as a descriptive fact, it could then become reformulated as a prescriptive ideal. No longer do we say it is the case that the universe is as full of potentials as it possibly could be; we now say that it should be. Does the fact that some prescriptions appear to be secularised residues of older religious ideas delegitimise them? I don’t think it does, but it should make us cautious. And, in my eyes, there is continuity between older metaphysical visions of Plenitude and contemporary visions of escaping extinction and filling the cosmos with maximal value.

Threads, directed by Mick Jackson (1984) tracks the aftermath of a thermonuclear blast in Sheffield. The film was the first to depict what’s become known as a “nuclear winter”. In the end, a ravaged society resumes using crude forms of steam power.

Venomous Lumpsucker by Ned Beauman, 2022.

We have to be careful with the blanket assumption that, as an individual learns and accumulates wisdom over time, so does the species itself

PW We are talking about finitude and infinitude here. On one hand, some people think that the very finiteness of human life is what gives it meaning. A representative thinker here is Martin Hägglund, who wrote a book called This Life: Secular Faith and Spiritual Freedom (2019). His basic point is that if you have a finite amount of time to act, then how you spend it becomes meaningful; making one choice rather than another becomes important. This implies that if you had an infinite amount of time, you couldn’t make any meaningful choices, because every alternative would eventually happen. This is another form of Plenitude.

I have a certain level of sympathy for this view: that having limited time and resources makes your choices more meaningful. But I think we’ve got to be careful about how we formally construe this opposition between the finite and the infinite. Infinity is not totality. There may always be more to do. To truly confront the thought of extinction – this expanding sequence of Deaths – is to recognise that there will never be enough time or energy in the universe to do everything that might be worthwhile. Maybe we will, at some point, exhaust all interesting possibilities within a given field, but it’s not obvious that we always must, when the field and its limits expand. The medium itself evolves.

TM Exactly. This idea that finitude alone confers value is something I’ve always been suspicious of. I think of it as a type of “Stockholm Syndrome for the human condition”. What’s more, it is the often unacknowledged assumption that the universe does have a limit to the set of possibilities within it that leads to the idea that there is an optimal state for the universe to be in. But this assumption is being increasingly questioned in modern evolutionary thought, particularly in the work of scientists like Stuart Kauffman or Sara Imari Walker. As systems become more complex, they gain more affordances. There’s nothing inevitable in complexification, but it’s plausible to imagine this gain outpacing the time available for the universe to explore all these multiplying affordances. Given the basic biochemical building blocks that we’re aware of, it’s feasible that there isn’t enough time available to explore every combination or evolutionary outcome that could occur. That means we live in a genuinely historical universe, because history matters when not every outcome will come to pass regardless. This is a further destruction of Plenitude: I don’t think that the finitude this entails confers intrinsic value on anything, but it does make decisions important, and that’s integral to valuing what we make of that history.

PW I do think constraints upon action are sources of meaning. It’s also worth distinguishing value and meaning: meaning is a type of value specific to life itself, in the sense of a personal life. Lives can be more or less meaningful, more or less fulfilled. I think constraint and challenge are essential sources of meaning, and the choices we make under constraint are therefore very significant.

TM This structure of First, Second, Third and Fourth Deaths we discussed earlier is an expansion of the arena within which we recognise that history matters. We might call it the horizon of contingency: the area of space and time, expanding outwards from our biographical lives, wherein we recognise that consequences or decisions matter because not everything is inevitable and not every outcome will randomly come to pass regardless. In our own childhood development, there’s a recognition of this kind of horizon within our own lives. For example, if I break my spine, I might not be able to walk again. Because that outcome isn’t inevitable, I endeavour to avoid breaking my spine.

Expanding from the biographical, humanity itself has slowly, over the generations, come to recognise that this also applies to the collective human story. Before the circumnavigation of the globe and the compilation of archaeological records, it was unclear whether human history had ever “begun” in a meaningful sense. Accordingly, people thought every historical possibility had already occurred and would re-occur, meaning the human story had no discernable shape nor permitted any permanence of choice or consequence. But then we discovered that humanity is a recent arrival on a much older Earth. By inserting a clear backward stop or bookend on past human history, this liberated the future: revealing that there might be things that can be achieved that haven’t already been achieved, or risks that are unprecedented.

PW There’s a hilarious satirical book by Ned Beauman called Venomous Lumpsucker (2022), which is also filled with this real pathos about permanent loss. It suggests that even horrific parasites are thermodynamic miracles whose extinction might be mourned. This captures what I’ve been saying about the aesthetic attitude towards nature and ecology. If you think of biodiversity as sheer quantity, it’s easy for it to become instrumentalised: having more biodiversity is good for us, having less is bad for us. This is true from an ethical perspective, but there is also a sense that worldly diversity and novelty are things we want for their own sake, in an amoral way.

TM Darwin teaches us that complicated objects do not spontaneously pop out of the ether. They require deep cumulative processes, which also means that entities of that class are not going to appear anywhere ever again, shorn of ties of propagation in time or migration in space. One consequence of this is that every species is tethered to the planet of its origin. Confronting that we live in a historical universe where evolution is non-ergodic, meaning that not every outcome will eventually manifest regardless of what happens now, we arrive at the idea that all species are cosmically unique and, thus, cosmically endangered. If we die out here and now, we die out everywhere, forever.

Plenitude as a prescriptive ideal does still appeal to me in lots of ways: greening the galaxy, filling it with life and diversity. At the same time, if we want the most possible species that can exist in this universe to exist, then we also want the most possible parasites in this universe. Fecundity, perhaps, is never purely virtuous in and of itself.

PW Many philosophers think that there is some kind of intrinsic value in novelty and diversity, though they often can’t say why. Eliezer Yudkowsky treats human values, which bundle together concerns with happiness, justice, and challenge, as just one possible utility function among many others. This makes them fragile, because slight perturbations result in radically different outcomes under optimisation. For example, a superintelligent AI that prioritises human happiness might decide to kidnap us and forcibly stimulate our pleasure centres. And yet, he treats preserving these values as a matter of the utmost importance, because the over-optimised worlds that AI alignment researchers fear are universes without fun. He uses ‘fun’ as a technical term, but it essentially involves novelty, diversity and ongoing challenge.

By contrast, the various stripes of utilitarianism tend towards homogeneity: if you’re a hedonic utilitarian, the best universe is one filled with a substance engineered to experience maximum pleasure; if you’re a preference utilitarian, it’s one filled with agents engineered to experience maximum satisfaction. But these identikit universes seem aesthetically ugly in a really fundamental way. How can we justify the idea that novelty and diversity are important enough to forgo universal optimisation? I think the answer relates to our contingency as historical entities. What makes us autonomous agents that choose for themselves isn’t where we start out, but how we change over time. It’s the way that our preferences, projects and principles evolve in unpredictable but essentially non-random ways. The drama of our lives. We are machines that turn natural contingency into practical contingency. Free in our beauty, and beautiful in our freedom.

TM John Milton captured this very well in Paradise Lost. He said that Adam and Eve were “sufficient to have stood, though free to fall”. Jeopardy is entirely part of agency and, therefore, value. .