Philosophy prof Jonathan Birch, principal investigator of the Animal Sentience Project at the London School of Economics, has written a book on whether and how animals feel things: The Edge of Sentience (Oxford University Press 2024).

It’s not as arcane a topic as it might at first appear. It shows up in new legislation and think tanks. At Amazon, we learn, for example, “In 2021, he led a review for the UK government that shaped the Animal Welfare (Sentience) Act 2022. In 2022-23, he was part of a working group that investigated the question of sentience in AI.” And as Birch told Marc Bekoff at Psychology Today,

I’m probably best-known for my work on invertebrate sentience, which is one part of the book. My team’s work has led to some invertebrates—octopuses, squid, cuttlefish, crabs, lobsters, shrimps—being included in the UK’s Animal Welfare (Sentience) Act 2022. And I was pleased to see our work cited in a new law banning octopus farming in California. But there is far more to do. I don’t want the focus on octopuses to lead to us forgetting about insects, which are also “sentience candidates” (in the way I define that term). The emerging insect farming industry needs to take welfare more seriously.

“The Edge of Sentience: Why Drawing Lines Is So Difficult, November 27, 2024”

The compendium of research findings, legislative initiatives, and proposals Birch provides certainly earns the book a place on the shelves of those researching the topics.

But there is another — much more concerning — reason to pay close attention to this new animal rights movement as well.

First things first:

Sentience vs. intelligence

Some animals, like dogs and cats, have not only the ability to feel (sentience) but the ability to tell us so directly, though not in words. But does coral really have sentience? Why? One is naturally drawn to the question of what an expert like Birch thinks about the many cases in the middle, the ones that surprise us, like the octopus and the lobster?

Birch’s view is generally an expansive one:

… it is important to note that sentience is also not the same as intelligence. Intelligence can give us a window into sentience, by making new types of sentience-relevant experiment possible. As a limiting case, consider how our intelligence, as humans, makes it easier for researchers to investigate our sentience, because we can verbally report what we are feeling. In a similar vein, the octopus is able to deploy its intelligence to succeed at tasks that are primarily testing for sentience.

In this sense, intelligence and sentience are methodologically linked: a high degree of the former can open up new methods of detecting the latter. But they are not the same property. Crucially, we need to be open to the possibility that animals which fail to set the world alight with their intelligence may nonetheless be sentient. That is an important lesson to bear in mind when considering other invertebrate taxa—such as crabs and lobsters. (p. 239)

He puts in a word for insect sentience as well: “I propose that all adult insects are sentience candidates, since all possess a central complex. It would be a double standard to restrict our precautionary thinking to just some insects, while extending it to all fishes. Why ‘adult’ insects? The central complex is not fully developed in larvae, so Barron and Klein’s argument only extends as far as adult insects.” (p. 272)

Birch makes clear that he is not a panpsychist (everything is conscious) or biopsychist (everything is sentient); he does not wish to go further than the available research. (pp. 60–61)

What about sentience in AI?

There, Birch thinks, we face different problems:

… the difficulties we face in this area are even greater than those we face in the case of other animals. Other animals are not capable of gaming our criteria. They do not have an internet-sized corpus of training data to mine for effective ways of persuading human observers. So, when animals display a pattern of behaviour that is well explained by a feeling (such as pain), the best explanation is usually that they do indeed have that feeling. With AI, by contrast, two explanations compete: maybe the system has feelings, but maybe it is just responding as a human would respond, exploiting its vast reservoir of data on how humans express their feelings. (p. 16)

It’s not clear that there is a way around the problem he outlines. Upping the AI-is-just-around-the-corner hype is much easier than thinking through the problems, as those who cover the industry have had good reason to see.

But the picture changes markedly when it comes to unwanted children

With human babies, those who propose laws against cruelty suddenly enter a Cold Zone, at least compared to their feelings for crustaceans:

When we turn to fetuses, a concern arises that recognizing fetal sentience may be incompatible with recognizing a right to abortion. However, these are substantially separate issues. The time limit for abortions depends either on when the fetus becomes a person and/or on the strength of a person’s right to bodily autonomy. Sentience is not sufficient for personhood, so this is not fundamentally a question about sentience. (p. 214)

Personhood is, of course, purely a legal concept. States that do not require children born alive from abortions to be cared for do not recognize personhood even when the child is no longer inside the mother. There, abortion is the right to a dead baby, inside or outside.

Then we read,

We should recognize human fetuses as sentience candidates from the start of the second trimester. This aligns with the earliest scientifically credible, evidence-based estimates in the zone of reasonable disagreement. Future evidence could move the threshold for sentience candidature in either direction, but it should always align with the earliest scientifically credible, evidence-based estimate. (p. 214)

But remember, Birch has made clear that sentience confers no right to protection on the child so,

Whenever therapeutic surgery is performed on a fetus (and this happens for a variety of reasons), direct administration of anaesthesia and pain relief should be considered. This can be justified by the need to control the fetal stress response, even setting aside the possibility of sentience. Specific decisions need to be made by expert anaesthesiologists in discussion with surgeons and patients, but the public can and should be involved in discussions of the general norms of medical practice in this area and the value-judgements implicit in those norms.

Although recognizing second-trimester fetuses as sentience candidates does not give us a reason to change the legal time limit on abortions, it does require honest communication of uncertainty with patients. Clinical norms in this area need to be formulated by appropriately inclusive processes, and these processes need to give appropriate weight to the voices of women. (p. 214)

The uncertain bureaucratic prose here largely — but not entirely — obscures the message, perhaps by design. My rough translation: It is at least reasonable in principle to give wanted children undergoing prenatal surgery pain relief. But if a child of the same age is to be killed in an abortion — and it might add to the distress of the aborting mother to make pain relief for that child part of the procedure — we should “give appropriate weight to the voices of women.” In other words, no pain relief?

If Birch doesn’t mean that, it is surely unclear what he does mean. If he does mean that, the right to abortion means not only the right to a dead baby but the right to one who died in horrible pain.

That’s the second part I mentioned above, the part we should pay close attention to. Birch — and he is not alone — wants us to care about lobsters. And yet he seems to thinks this way about living children!

It’s helpful to keep such sharp divergences in mind whenever we hear from animal rights advocates.