The Edge of Sentience: Risk and Precaution in Humans, Other Animals, and AI is a 2024 book by British philosopher Jonathan Birch, published by Oxford University Press. It examines ethical and policy questions raised by uncertainty about sentience, defined as the capacity for subjective experience. Birch outlines a precautionary approach to ethical decision-making, arguing that moral consideration should extend to beings for which there is credible evidence or possibility of sentience. The book discusses how this framework may apply to humans, non-human animals, and artificial intelligence systems.
The book introduces the concept of a "sentience candidate" to describe systems that may plausibly be sentient. It explores examples including people with disorders of consciousness, human fetuses, brain organoids, cephalopods, crustaceans, and artificial intelligence. Birch argues that policymaking should prioritise the avoidance of suffering and rely on proportional and democratically informed precautions.
The Edge of Sentience has been reviewed in publications including 3 Quarks Daily, Leonardo, and Biosemiotics. Reviewers discussed the book's application of precautionary reasoning to questions of sentience and its focus on integrating ethical reflection with policy. It was launched at events hosted by New York University and the London School of Economics.
Background
Birch in 2023
Jonathan Birch is a professor of philosophy at the London School of Economics and principal investigator of the Foundations of Animal Sentience project. In 2021, he chaired a government-commissioned review of scientific evidence on sentience in cephalopod molluscs and decapod crustaceans. The review's findings informed the United Kingdom's decision to extend legal recognition of sentience to invertebrates, including octopuses, crabs, and lobsters, through the Animal Welfare (Sentience) Act 2022.[1]
Birch wrote The Edge of Sentience to explore the ethical and policy issues that arise when assessing whether certain beings—such as invertebrates, brain organoids, or AI systems—are sentient. These cases are described as being at the "edge of sentience". The book focuses on how policymakers can act responsibly amid uncertainty about sentience, emphasising practical reasoning and proportional precaution rather than speculative theories of consciousness.[2]
Summary
The Edge of Sentience develops a framework for ethical decision-making in situations where the presence of sentience is uncertain but morally significant. Jonathan Birch defines sentience as the capacity for valenced experience, meaning experiences that feel pleasant or unpleasant to the subject. He distinguishes this from broader notions of consciousness and intelligence, arguing that sentience alone provides sufficient grounds for moral consideration.
The book examines cases in which sentience is uncertain, such as people with disorders of consciousness, human fetuses, brain organoids, non-human animals like cephalopods and crustaceans, and artificial intelligence systems. Birch discusses how precautionary reasoning can inform ethical and policy responses in these contexts.
Central to the book is the idea of the "sentience candidate", a system for which there is a credible, non-negligible possibility of sentience. Birch argues that when such a possibility exists, ignoring potential suffering is ethically reckless. His proposed framework is based on three principles: a duty to avoid gratuitous suffering, recognition of sentience candidature as morally significant, and the importance of democratic deliberation about appropriate precautionary measures.
The book applies this framework to practical areas including medical ethics, research on organoids and fetuses, invertebrate welfare in agriculture, and regulation of artificial intelligence. Birch contends that policy should be guided not by certainty but by precaution and proportionality, prioritising the avoidance of suffering where the risks are serious or irreversible.
Rather than resolving the philosophical problem of other minds, Birch focuses on responsible action under uncertainty. He maintains that although the limits of sentience may remain indeterminate, ethical decision-making can still proceed through principles of precaution, proportionality, and accountability.
Reception
In 3 Quarks Daily, Mike O'Brien described The Edge of Sentience as a clear and policy-oriented contribution to public philosophy. He wrote that Jonathan Birch develops a systematic framework for addressing uncertainty about sentience in humans, animals, and artificial intelligence, based on duties to prevent suffering and to promote democratic decision-making. O'Brien noted the book's focus on practical reasoning and its avoidance of speculative claims. He questioned whether democratic consultation is always the best means of representing non-human interests but regarded Birch's position as a workable approach within existing institutions.[3]
In a review for Leonardo, Gregory F. Tague discussed the book's treatment of ethical and policy issues concerning sentience in humans, animals, and artificial intelligence. He noted Birch's emphasis on caution and public involvement when evidence of sentience is uncertain, describing the book as accessible and relevant to debates in animal ethics and AI ethics. Tague encouraged further discussion on how precautionary principles can guide policy in emerging scientific fields.[4]
Writing in Biosemiotics, Claudio Julio Rodríguez Higuera discussed the book's relevance to research on sentience and ethics in policy. He observed that although Birch does not explicitly address biosemiotics, its perspectives on communication and value in non-human organisms could complement Birch's framework. Rodríguez Higuera suggested that the book's policy-based ethics may contribute to broader interdisciplinary exchanges between biosemiotics and philosophy of mind.[5]
Public engagement
A book launch event was held at Lipton Hall, NYU School of Law, on 11 November 2024.[6] Birch also gave a public lecture at the London School of Economics on 3 December 2024. The event, titled The Edge of Sentience: Risk and Precaution in Humans, Other Animals, and AI, explored key arguments from the book and their implications for ethics and public policy.[1]
Publication history
The book was first published online as an open access title by Oxford University Press on 19 July 2024. Its cover was illustrated by Anna Zeligowski.[7] A hardback version was released on 15 August 2024.[8] An audiobook version, narrated by Graham Mack, was published by HighBridge Audio on 18 February 2025.[9]
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