Jonathan Birch in Talking Animals, Law & Philosophy
When comparing welfare in the human case, we face a serious problem of interpersonal comparison. Two people may not experience the same deprivations in the same way, and there is an inscrutable private element to these experiences. This problem is part of what motivates the "Capabilities Approach", which aims to make comparisons through objectively measurable indices of capabilities relevant for flourishing. In the non-human case, we face even more serious problems of comparison. Can an expanded version of the Capabilities Approach (such as that defended by Martha Nussbaum) help with these? I think the answer is: maybe, if we can first agree on expanded principles of interspecies justice/fairness analogous to those that underlie the human version of the Capabilities Approach. But agreement on those underlying principles will be hard to achieve.
Jonathan Birch is a Professor of Philosophy at the LSE and Principal Investigator on the Foundations of Animal Sentience project. In 2021, he led a "Review of the Evidence of Sentience in Cephalopod Molluscs and Decapod Crustaceans" that led to invertebrate animals including octopuses, crabs and lobsters being included in the UK government's Sentience Bill. In addition to his interest in animal sentience, cognition and welfare, he also has a longstanding interest in the evolution of altruism and social behaviour. His first book, published in 2017, was entitled The Philosophy of Social Evolution.