Contributor(s): Professor Jonathan Birch | Can octopuses feel pain and pleasure? What about crabs, shrimps, insects or spiders? How do we tell whether a person unresponsive after severe brain injury might be suffering? When does a fetus in the womb start to have conscious experiences? Could there even be rudimentary feelings in miniature models of the human brain, grown from human stem cells? And what about AI? These are questions about the "edge of sentience", and they are subject to enormous, disorienting uncertainty. The stakes are immense, and neglecting the risks can have terrible costs. We need to err on the side of caution in these cases, yet it’s often far from clear what ‘erring on the side of caution’ should mean in practice. When are we going too far? When are we not doing enough? Birch's new book, The Edge of Sentience: Risk and Precaution in Humans, Other Animals, and AI, constructs a precautionary framework designed to help us reach ethically sound, evidence-based decisions despite our uncertainty. This talk will introduce some of the main themes of the book.