This special issue is devoted to the question of sentience and its ethical implications. Sparked by debates in contemporary science and bioethics, the theme addresses one of the most fundamental and contested concepts in moral philosophy: what it means to be sentient, why it matters, and how our understanding of it should guide practices, policies, and ethical reasoning. While the idea of sentience has long been central to questions of moral standing, recent developments—from neuroscientific models to artificial intelligence—have made it increasingly urgent to clarify its nature, scope, and significance. The contributions in this volume approach these issues from a range of philosophical, scientific, and applied perspectives, showing how the concept of sentience both challenges and enriches contemporary ethics.

This interview with Peter Singer AI serves a dual purpose. It is an exploration of certain—utilitarian and related—views on sentience and its ethical implications. It is also an exercise in the emerging interaction between natural and artificial intelligence, presented not as just ethics of AI but perhaps more importantly, as ethics with AI. The one asking the questions—Matti Häyry—is a person, in the contemporary sense of the word, sentient and self-aware, whereas Peter Singer AI is an artificial intelligence persona, created by Sankalpa Ghose, a person, through dialogue with Peter Singer, a person, to programmatically model and incorporate the latter’s writings, presentations, recipes, and character qualities as a renowned philosopher. The interview indicates some subtle differences between natural perspectives and artificial representation, suggesting directions for further development. PSai, as the project is also known, is available to anyone to chat with, anywhere in the world, on almost any topic, in almost any language, at www.petersinger.ai

I aim to make progress on the following question: When is it morally wrong to risk harming another being? I will pay special attention to the use of the roundworm Caenorhabditis elegans (C. elegans), but my points are relevant to other situations and beings. I focus on the motive or purpose for exposing a being to risk of harm. I argue that it is morally wrong to potentially harm a being for the sake of others’ positive well-being or for a purported good such as knowledge (that is, knowledge for its own sake). The practical ramifications include that there is a moral hurdle of justification for potentially harming another being, and the justification cannot be others’ positive well-being or a good such as knowledge. Essentially, if the use of a being can be morally justified, it needs to be justified based on reducing enough ill-being or unpleasantness. One should recognise the creation and use of beings as a moral issue and view any warranted potential harm as a regrettable lesser evil. If feasible, it is desirable to use alternative methods that carry less risk and do not involve potentially sentient beings.

Pain is often portrayed as the guardian of life. Unpleasant sensations are undisputedly in the service of the self-preservation of living beings. However, it is questionable whether the first sensations in evolution must have been those of pain. The emergence of a new property cannot be derived from the function that the property has once it is there. In evolution, new properties are not produced by needs (this would be teleological thinking), but by mutations and selection. Accordingly, rather than pain, the first sensation of an early creature may just as well have been a neutral (or pleasant) sensation. Furthermore, it is conceivable that the self-preservation of early organisms and evolutionarily old and successful species (such as bacteria or jellyfish) is achieved by biochemical processes without the involvement of consciousness. The individuals of evolutionarily very old extant species may still have a kind of luxury primitive consciousness (restricted to neutral or pleasant sensations) hovering above organismal needs. This has ramifications as regards argumentative standards of antinatalist moral theory, for example.

In this article, it is argued that in the actual world, even if not in all possible worlds, sentience is both a necessary and sufficient condition for having moral standing. In arguing for this conclusion, the concepts of sentience and moral standing are explained. Five kinds of interest are then differentiated—functional, biotic, sentient, sapient, and self-conscious. It is argued that having sentient interests, rather than merely any interests, is what grounds moral standing. However, determining who has moral standing is only a beginning. Once we know whose interests we need to consider, we still need to know what interests need to be considered. We also need to know what considering those interests implies. Those questions are engaged in the remainder of this article.

This article presents five arguments against the idea that non-sentience is a sufficient condition for not considering abortion an immoral act: the formal paradox argument, the third-person argument, the abortionist status argument, the implicit antinatalist premise argument, and the manipulation argument. These five arguments do not disqualify pro-abortion approaches that do not use the element of non-sentience but suggest that it would be appropriate for these approaches to also consider them. The existence of these other pro-abortion arguments shows that non-sentience is not a necessary condition either for trying to show that abortion is not immoral.

This paper revisits the longstanding debate over the nature of suffering, focusing on the divide between subjective and objective accounts. I defend a Personalist conception of suffering, rooted in an Aristotelian understanding of human flourishing, that recognizes suffering as both universally human and deeply personal. On this view, suffering is neither a purely sentient, inner experience nor reducible to external conditions, but a disruption of flourishing that arises when love or justice is violated or absent—and that calls for a communal response. Understood through this lens, suffering, I argue, invites a shared practice of meaning-making—not as sentimental optimism but as a form of grounded hope: realistic, responsive, and attuned to the dignity of both the sufferer and those who accompany them. Even when suffering cannot be cured or fully comprehended, it can be met with deeper engagement, mutual responsibility, and a reaffirmation of our commitment to a life lived in relation and shared purpose.

Neural organoids derived from pluripotent stem cells have sparked ethical debate because, it is claimed, they could be sentient, or could develop sentience. We critically assess three routes for defending such a possibility: analogy with known sentient organisms, inference from neural function using leading theories of consciousness, and foundational philosophical commitments. Current cortical organoids lack nociceptors, sensory integration, and behavioral repertoires necessary for analogical arguments; they also fall short of the structural differentiation presupposed by most empirically grounded consciousness theories, rendering existing neural metrics unreliable. Even if constitutive panpsychism were accepted, the moral relevance of any putative micro experiences would remain undetermined. Precautionary appeals, therefore, hinge on how the term “possible” is interpreted. We argue that regulatory or experimental restrictions are warranted only once there is a non-trivial empirical likelihood that a given organoid type can generate valenced experience. Given present technological limits on size, complexity, and vascularization, that threshold has not been reached, nor is it likely to be met in the near to medium term. This claim is contingent on the current state of research, but we believe it to be justified. Our analysis clarifies conceptual ambiguities surrounding organoid sentience and offers a principled framework for proportionate precaution.

Initiatives protecting wild animal health, including vaccination campaigns, medical treatments, and parasite control programs, have been implemented for decades. Their goal has been to safeguard human well-being, as well as to further conservationist goals. This paper argues that the well-being of wild animals, considered as sentient individuals, should be another crucial reason to expand these measures. Rather than treating animal health in a purely instrumental manner, this perspective aligns more closely with the ethos of the One Health paradigm. The paper presents examples of existing programs that benefit wild animals and could be broadened based on this idea. Next, it explains the kind of cross-disciplinary research framework—integrating animal welfare science, ecology, and other disciplines—needed to successfully develop effective ways to help wild animals. It then argues that the reasons to protect wild animal health also apply in the case of other ways to help wild animals. This is relevant especially in light of the very large scale of wild animal suffering.

Legal and ethical frameworks remain dominated by a broadly binary conception of moral status as the primary organising idea: entities are typically treated either as persons, with extensive rights, or as things, with at best limited protections. While many jurisdictions now recognise animal welfare and anti-cruelty duties, these measures generally stop short of acknowledging independent full moral status. This landscape is ill-suited to the diversity of entities whose capacities challenge existing categories, from nonhuman animals to unprecedented beings. This article proposes a pragmatic spectrum of moral status, conceptualised as a continuous gradient on which entities can be located according to their morally relevant capacities. Grounded in a triangulation of established ethical theories, the framework is structured by three anchor thresholds—sentience, consciousness, and sapience—allowing graduated protections to “kick in” at different points. The spectrum is applied using a multimodal approach to measurement, demonstrating how it can guide governance where current law leaves a vacuum. By moving beyond the person/thing distinction with a capacity-based continuum, this approach offers a flexible, anticipatory tool for recognising and responding to the moral claims of diverse entities while avoiding both overreach and neglect.

Ethical thinking can be pragmatically framed as striving for impact in improving the world, without relying on traditional moral language. Consciousness or sentience is central to anything mattering, but only suffering has an inherent urgency to be addressed. This call to action applies regardless of species or physical substrate. From a perspective on personal identity that recognizes separateness as an illusion, the most extreme suffering can be considered intolerable per se, not just for the physical being experiencing it. Prioritizing the prevention of such suffering is therefore rational. Strong, potentially competing intuitions, including the desire to thrive, must also be accommodated for an ethical framework to be viable, without the creation of happiness formally balancing out intense suffering that exists elsewhere. A framework termed “xNU+” captures these considerations. Suffering metrics such as Years Lived with Severe Suffering (YLSS) and Days Lived with Extreme Suffering (DLES), used alongside existing health and well-being metrics, would better track what matters, in humans and, using different methodologies, in other species and potential artificial sentient entities. The rapid, potentially irreversible, technology-driven transformations now occurring on our planet make it urgent that we embed a suffering-focused ethical framework in our governance and policy-making.

This paper explores sentiocentric antinatalism, which is based on two principles: (1) prevention of the emergence of pain and (2) antispeciesism. It argues that the notion that all sentient creatures, including humans, should not be born presents an unsolvable paradox; the paradox is that the antinatalists who attempt to eliminate all births of sentient creatures must bear the obligation to survive for the purpose of preventing the emergence of all other creatures in this world. There are four phases to their attempt, and corresponding to them, there are four obligations that antinatalists should bear in pursuit of their ultimate mission. In the last part of this paper, the paradox of antinatalism is compared to the paradox of time travel, and their similarities and differences are discussed. In addition, antinatalists’ obligations are discussed in terms of supererogation.

While David Benatar’s 2006 book Better Never to Have Been: The Harm of Coming into Existence remains the most influential formulation of contemporary academic antinatalism, numerous other iterations, both academic and nonacademic, have emerged since its publication. These newer forms reflect differing styles, motivations, and normative commitments across a range of issues, none more contentious than the question of what duties human antinatalists may hold toward nonhuman animals or life more broadly. This debate has produced a significant division within antinatalisms. Anthropocentric forms endorse the voluntary extinction of humanity while allowing other life to continue. Sentiocentric forms recommend the eventual extinction of all sentient life. While humans could voluntarily choose to cease reproducing, sentiocentric antinatalism implies, sometimes explicitly requires, active human intervention to end the reproduction of other sentient beings, potentially involving coercion or violence. This paper builds upon Patricia MacCormack’s critique of Benatarian antinatalism and efilism in her 2020 book The Ahuman Manifesto: Activism for the End of the Anthropocene. By widening the scope of inquiry to include multiple antinatalist traditions, the analysis maps how and why some formulations of antinatalism come to endorse forceful or promortalist positions aimed at achieving the extinction of certain, even all, species.

The ethically reflective assessment of life reveals a paradox. On the one hand, many people regard life as one of the highest values and celebrate each new life. On the other hand, every sentient life is inevitably exposed to suffering. Why, then, do we usually consider sentient life worth starting, despite the fact that, apart from a relatively small group of antinatalists, this judgment is rarely questioned? In this article, I argue that sentience is not an advantage but a disadvantage because its central negative consequence is unavoidable suffering for every sentient being. I further argue that bioethics and healthcare ethics should take antinatalist intuitions more seriously in order to challenge pronatalist assumptions that normalize procreation and, in doing so, magnify eradicable suffering.

David Benatar’s Better Never to Have Been (2006) presents a view that came to be known as antinatalism: the claim that it is always wrong to have children, because life is bad, death is bad, and the only way to avoid both is never to be brought into existence. Benatar argues that his two-barreled—or “bipolar”—pessimism is not limited to humans but applies equally to all sentient beings. This extension, however, is prone to producing theoretical confusion. The anti-reproductive view laid out in the book is coherent as a form of human antinatalism, but Benatar’s own caveats prevent it from developing into the radical sentiocentrism it seems to promise.