by Tim Sommers
Here’s the gist of it. I think a recent declaration on animal consciousness, being signed by a growing number of philosophers and scientists, is largely correct about nonhuman animals possessing consciousness, but misleading. It insinuates that animal consciousness is a recent discovery – made in the last five to ten years – based on new experimental work. As exciting and revelatory as recent work on the minds of nonhuman animals is, animal consciousness is hardly a new discovery. In fact, I am not sure the declaration is really a scientific manifesto so much as a moral one. We ought to be treating nonhuman animals better because many seem to have some level of consciousness, but implying we should do so because of new “scientific evidence” may be a mistake.
NBC recently reported that “discoveries…in the last five years” show that a “surprising range of creatures” exhibit “evidence of conscious thought or experience, including insects, fish and some crustaceans.”
“That has prompted a group of top researchers on animal cognition to publish a new pronouncement that they hope will transform how scientists and society view — and care — for animals.”
“Nearly 40 researchers signed The New York Declaration on Animal Consciousness, which was first presented at a conference at New York University.” Many more have signed the Declaration since then, and many more are likely to sign it in the near future.
Here is The New York Declaration on Animal Consciousness in its entirety.
“Which animals have the capacity for conscious experience? While much uncertainty remains, some points of wide agreement have emerged.
First, there is strong scientific support for attributions of conscious experience to other mammals and to birds.
Second, the empirical evidence indicates at least a realistic possibility of conscious experience in all vertebrates (including reptiles, amphibians, and fishes) and many invertebrates (including, at minimum, cephalopod mollusks, decapod crustaceans, and insects).
Third, when there is a realistic possibility of conscious experience in an animal, it is irresponsible to ignore that possibility in decisions affecting that animal. We should consider welfare risks and use the evidence to inform our responses to these risks.”
When I read this my first reaction was “I can’t believe it, they’ve solved the ‘other minds’ problem!” A leading problem in philosophy, after all, has been ‘How do we even know other humans have consciousness?’ – much less nonhuman animals. In fact, one of the signatories to the declaration, leading philosopher of mind David Chalmers, is well-known for arguing that there might be beings (“philosophical zombies”) that look and behave just as we do, but have no consciousness. In other words, recognizing there is a philosophical problem about how we can be justified in attributing consciousness to others.
I don’t want to defend the view that we don’t know if other humans have consciousness, any more than I would want to defend the argument that we live in a simulation, but it’s worth noting that a solution to the problem is unlikely to be empirical or the outcome of an experiment. Moreover, given that we are very similar to other humans and have the ability to communicate with them, of course, we tend to attribute consciousness to each other. However, given our differences with other animals, the problem of nonhuman consciousness becomes orders of magnitude more difficult than the other minds problem.
Before I say more about the NY Declaration, I ought to note that it has a distinguished predecessor. In 2012, the Cambridge Declaration on Consciousness concluded:
“The absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”
That declaration also prominently features claims that their conclusions are based on “new techniques and strategies…of research,” though it seems to have been endorsed exclusively by scientists, unlike the NY Declaration where 28 of original signatories are philosophers. On the other hand, the Cambridge Declaration did not confine itself to experts in the field. (Stephen Hawkings attended the signing, for whatever that’s worth.) But the key to this earlier declaration is the way it frequently repeats the word “substrates.” To oversimplify, their arguments are based on the claim that many animals have the right neural anatomy (sufficiently similar to ours) to be capable of some kind of consciousness, even where the neural machinery is very different in many ways. The Cambridge Declaration, in other words, reads like a tacit rejection of functionalism.
Functionalism is the view that minds or states of mind – sentience, consciousness, cognition, etc. – are to be understood in terms of their functions or causal role. They do not depend for their existence on some underlying, fundamental substance, but on the role they play in the mind as a system. Mental states are multiply-realizable, then. Humans, dogs, octopuses, insects, and maybe alien or artificial beings, too, can all feel pain, on this view, even if the underlying neural substrate is very different. Some functionalists even argue that absolutely anything is potentially sufficient for realizing mentality – even enough people attached to each other by ropes. My point is that the evidence offered in the Cambridge Declaration, even though it countenances variety and does not demand too strict an isomorphism between human and nonhuman neural architecture, reinforces what functionalists deny. Namely, that the particularities of the system don’t matter at all.
What sort of the evidence does the NY Declaration adduce? In order to keep to a reasonable length, I am going to mention just one piece of evidence, but I think it is representative. I urge you to check out the “Background” section of the NY Declaration if you disagree. In fact, I urge you to check it out either way. This research is fascinating and amazing. Again, my only disagreement is with how the Declaration as a whole is presented.
Here’s the study mentioned. “Questions of self-awareness in animals have long been explored using the “mirror-mark test,” which tests whether an animal, upon seeing a mark on their own body in a mirror, will try to remove that mark. In a surprising series of studies between 2019 and 2023, researchers showed that cleaner wrasse fish can pass the four phases of the test. First, when exposed to a mirror, the fish react aggressively as though they believe they see a rival fish. Second, the aggression fades and the fish begin performing unusual behaviors in front of the mirror, such as swimming upside down. Third, the fish seem to study themselves in the mirror. Finally, after the experimenters place a colored mark on the fish, the fish, on seeing the mark in the mirror, attempt to remove it by scraping against an available surface.”
Here’s the thing. The mirror-mark test was developed 54 years ago and has been used many times on a wide-variety of animals. It’s cool that wrasse fish can pass it, but it’s another of many examples accumulated over many years, not a new development appropriately classed under the title of “Recent Rapid Advances,” as it is in the NY Declaration. More to the point, why do we even need mirror-mark tests, or the like, to conclude most, if not all, animals possess at least a minimal “phenomenal consciousness” or “sentience”? Hasn’t any of the signatories had a dog or a car? We have plenty of evidence that animals can feel pleasure and pain and more.
The point is not that the declaration is wrong when it says that “when there is a realistic possibility of conscious experience in an animal, it is irresponsible to ignore that possibility in decisions affecting that animal.” It’s just that Bentham said the same thing better in 1789 when he said that when it comes to nonhuman animals, “The question is not, Can they reason? nor Can they talk? but, Can they suffer? Why should the law refuse its protection to any sensitive being?”
If we let our duty to take more seriously the welfare of nonhuman animals turn on scientific evidence of more sophisticated kinds of consciousness or cognition among animals than previously recognized, we make the case for kindness more, not less, tenuous. I get that this goes against most people’s intuition that moral propositions are more subjective or tenuous than factual ones, so let me end with a thought experiment.
Consider these two propositions. “The Earth goes around the Sun.” And “It’s wrong to torture kittens for fun.” Could anything change your mind about either of these? Setting aside claims like the kitten is not really a kitten but a robot and the sun is just an illusion created by aliens, it’s conceivable to me, however unlikely, that you could tell me a story that accounted for all of the scientific of heliocentrism but which ultimately put the Earth back at the center of the solar system. But it’s inconceivable to me that there is a story you could tell to convince me that it is not wrong torture kittens. I believe that in the web of belief, a principle forbidding such torture is less open to revision than facts about the orbit of the Sun and the Earth. Moral principles need moral, not scientific, justification.