The Oxford English Dictionary, my go-to source for definitions, has this one for “consciousness”:
But there are other definitions, including sensing “qualia” (subjective conscious experience like pleasure or pain), or “having an inner life” involving self-awareness. But it’s hard to determine under any of these definitions whether an individual of another species—indeed, even an individual of our own species—is conscious. We think that other humans are conscious because we’re all built the same way, and we’re pretty sure that other mammals are conscious because they appear to feel pain or pleasure, and are built in a mammalian ground plan. But when an earthworm reacts when you poke it, is it feeling pain and having a subjective experience, or is that an automatic, built-in response to being poked that is adaptive but isn’t mediated through conscious experience?
I’m not going to get into the thorny topic of consciousness here, but I do feel that the more an animal is conscious (whatever that means), the more we should take care of it and avoid hurting it. (This of course is a subjective decision on my part.) It’s probably okay to swat mosquitoes, but not to kill a lizard, a duck, or a cat. (I tend to err on the “assume consciousness” side, and am loath to even swat mosquitoes.)
Researchers themselves have arrived at similar conclusions, for there are increasingly stringent regulations for taking care of lab animals. If you work on primates or rats, you have to ensure your university or granting agency that your research subjects will be properly treated, but those regulations don’t apply to fruit flies. But whether members of another species are conscious in the way that we are (well, the way I am, as I can’t be sure about you!), is something very hard to determine. The “mirror test“, in which you put a mark on an animal’s forehead, put it in front of a mirror and see if it touches its own forehead, is another test used to determine self awareness. The article below describes several other ways scientists have approached the question.
At any rate, according to Nature, a group of scientists have signed short joint declaration (second link below) saying that we need more research on consciousness and that the phenomenon may be present “in all vertebrates (including reptiles, amphibians, and fishes) and many invertebrates (including, at minimum, cephalopod mollusks, decapod crustaceans, and insects).” They add that knowing whether an animal is conscious should affect how we consider its welfare, which seems correct. The letter (or petition) doesn’t really define “consciousness”, but the Nature blurb about it does. Click the link below to read that blurb:
An excerpt:
Crows, chimps and elephants: these and many other birds and mammals behave in ways that suggest they might be conscious. And the list does not end with vertebrates. Researchers are expanding their investigations of consciousness to a wider range of animals, including octopuses and even bees and flies.
Armed with such research, a coalition of scientists is calling for a rethink in the animal–human relationship. If there’s “a realistic possibility” of “conscious experience in an animal, it is irresponsible to ignore that possibility in decisions affecting that animal”, the researchers write in a document they call The New York Declaration on Animal Consciousness. Issued today during a meeting in New York City, the declaration also says that there is a “realistic possibility of conscious experience” in reptiles, fish, insects and other animals that have not always been considered to have inner lives, and “strong scientific support” for aspects of consciousness in birds and mammals.
As the evidence has accumulated, scientists are “taking the topic seriously, not dismissing it out of hand as a crazy idea in the way they might have in the past,” says Jonathan Birch, a philosopher at the London School of Economics and Political Science and one of the authors of the declaration.
The document, which had around 40 signatories early today, doesn’t state that there are definitive answers about which species are conscious. “What it says is there is sufficient evidence out there such that there’s a realistic possibility of some kinds of conscious experiences in species even quite distinct from humans,” says Anil Seth, director of the Centre for Consciousness Science at the University of Sussex near Brighton, UK, and one of the signatories. The authors hope that others will sign the declaration and that it will stimulate both more research into animal consciousness and more funding for the field.
And Nature says that the group has a definition of consciousness, though I can’t find it in the short declaration:
The definition of consciousness is complex, but the group focuses on an aspect of consciousness called sentience, often defined as the capacity to have subjective experiences, says Birch. For an animal, such experiences would include smelling, tasting, hearing or touching the world around itself, as well as feeling fear, pleasure or pain — in essence, what it is like to be that animal. But subjective experience does not require the capacity to think about one’s experiences.
This is as good a definition as any, I think, but determining whether another animal is even sentient is nearly impossible; all we can do is look for signs of sentience, like a dog howling if you kick it. But if a protozoan heads for a source of food, is it having a subjective experience of “here’s food”? Unlikely; protozoans don’t have brains and this is probably an inbuilt adaptive reflex. But there are tons of species intermediate in potential sentience between protozoans and mammals, and how do we decide whether, say, a fish is sentient? (I’ll tell you that scientists have ways of approaching this, but no time to go into it now. But the article has some interesting descriptions of these tests.) And of course most people think that octopuses are sentient. Some even think that fruit flies are sentient!:
Investigations of fruit flies (Drosophila melanogaster) show that they engage in both deep sleep and ‘active sleep’, in which their brain activity is the same as when they’re awake. “This is perhaps similar to what we call rapid eye movement sleep in humans, which is when we have our most vivid dreams, which we interpret as conscious experiences,” says Bruno van Swinderen, a biologist at the University of Queensland in Brisbane, Australia, who studies fruit flies’ behaviour and who also signed the declaration.
Some suggest that dreams are key components of being conscious, he notes. If flies and other invertebrates have active sleep, “then maybe this is as good a clue as any that they are perhaps conscious”.
Well that’s stretching it a bit, but who knows? And some people weigh in with the caveat I mentioned above: acting as if you’re conscious may not mean that you’re conscious, for consciousness produces adaptive behavior, but so does natural selection, which has the ability produce adaptive reflexes not mediated by consciousness but look like consciousness.
We have a hard problem, then, and that’s reflected in the declaration itself, which is below. You can see the whole thing as well as its signers by clicking on the screenshot:
And the text of the document:
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.
I don’t recognize many of the signers, and I’m surprised that Peter Singer, who surely agrees with the declaration, didn’t sign it. But I think more signers are being added.
At any rate, I can’t disagree with what the document says, but the interesting problems are both philosophical (on the ethical side) and scientific: what do we mean by consciousness, and, once that’s agreed on, how do we determine if a member of another species is conscious? Or, upon rethinking what I just wrote, perhaps we don’t need a definition of consciousness, but simply a set of empirical observations that we think are signs that animals are suffering. But that itself involves some philosophical input. It’s all a mess, but one thing is for sure, we should avoid causing unneeded suffering to animals, and we shouldn’t kill them just because we don’t like them. Even a lowly ant has evolved to preserve its own existence, and to what extent can our selfish desires override that consideration?
As the classic ending of many scientific papers goes, “More work needs to be done.”
h/t: Phil