A few weeks ago, I encountered four young raccoons while walking through campus at night. They all quickly scuttled up the same tree, but not very far, and they proceeded to all peer around one side of the trunk or the other, eyeing me curiously. I remained, and soon they cautiously descended and continued their adorable exploration of the grounds with their paws and noses. The sound of a distant car engine would send them all a few feet back up the trunk, but then they would come back down again, always watching me, appearing to be torn between fear and a deep wonder of who I was.
Appearing to be. Appearing to be experiencing life as fluffy raccoons, staring at a strange pale primate, feeling mixed emotions. But is there really anybody home in those little raccoon brains? Are raccoons actually conscious of their existence, actually awake and aware? Or are their brains just complex machines, controlling behavior by integrating sensory input and instinct, without any sentient perception of themselves and the world? Some philosophers, notably Descartes, have argued that non-humans animals have no consciousness. Others have observed the sophisticated behaviors and problem-solving abilities of pets or wildlife, and concluded that we are not the only species that is aware, that can feel pleasure and pain.
What baffles me it that we have yet to make any significant progress on this issue. After countless studies of animal behavior, neurobiology, psychology, and artificial intelligence, we still have no idea what consciousness actually is, how it arises, or how we could test for it. Maybe consciousness just somehow emerges once you build a big enough brain, or maybe it’s something else entirely, and not directly related to most of the tasks the brain performs. It does not seem like it can be reduced into simpler parts; you’re either awake inside or you’re not. If anything, science has shown us only that we know less than we thought we did, by demonstrating that intelligence is not highly correlated with consciousness. For example, we have created machines like my calculator, which I am pretty sure is not sentient, that clearly possess a type of intelligence, and that can perform many tasks more quickly or accurately than I ever could. So, the fact that a raccoon is intelligent, and can figure out how to break into a locked garbage can, says nothing about its consciousness. Thus, we have no objective way to detect consciousness; tests of intelligence are not enough.
Taking this train of thought to its logical conclusion, how do I know that any other humans besides myself are self-aware? Maybe you’re all just walking zombies with detailed software running thought your brains, sensing the world but asleep inside. Obviously, I don’t know this for sure, and I just have to go with a leap of faith, along with the inconclusive reasoning that your looks and actions are similar to mine, so your mind is probably like mine, too. Likewise, my gut tells me that raccoons have consciousness, also. As a scientist, though, this is profoundly unsatisfying. Where’s the hard data? I want to objectively determine which species have awareness. Just a handful, like chimps and dogs and dolphins? All mammals? What about birds, or other vertebrates? Any invertebrates? How could we figure this out? What kind of data could there even be that would be convincing?
One trick that evolutionary biologists use to figure out which species share a certain trait is to parsimoniously trace character evolution along an evolutionary tree. If we assume that consciousness is a complex trait that is unlikely to be gained or lost very often, then it probably existed in the most recent common ancestor of all living species that have it. So, if both humans and dogs are self-aware, then our most recent common ancestor was self-aware, and therefore so are all other species descended from that ancestor, including raccoons, whales, bats, and even the cows and pigs that many people eat. Of course, consciousness might have evolved independently multiple times, or be lost occasionally, and this method still doesn’t solve the problem of figuring out who else is conscious in the first place.
Our ignorance is frustrating, because consciousness is arguably the most important thing in the world. If nothing in the universe were able to feel joy or perceive beauty, then the universe has would have meaning. Value exists only because beings exist who can value their existence. We know almost nothing about this most important thing in the world. Furthermore, the ethical implications are staggering, since beings with self-awareness have intrinsic value, while those without it have only extrinsic value. We should have a master list of exactly which species can sense pleasure and pain, with all of the moral consequences that carries, but no such list exists. We can make some general presumptions, like that the presence of nerves might be associated with the ability to sense, but we have little justification for this. After all, you could easily make a robot with artificial nerves that senses and reacts to “pain,” but such behavior doesn’t mean it’s really feeling anything. On the other hand, as biotechnology and computer technology increase, we might actually create an artificial consciousness. We might have already. How would we know?
I remain cautiously optimistic for scientific progress on this question, perhaps torn between fear and curiosity just like the raccoons. In the meantime, I can only be thankful for the opportunity to be a conscious being in the world, to feel the cool damp air around me and smirk at the cute antics of four raccoons… and perhaps I will err on the side of caution and not abuse beings which potentially can sense the abuse. Consciousness is very real, yet just as mysterious and awe-inspiring as any concept from mythology or old-time religion. I do not know who my fellow participants on this blessed adventure might be, but if you are awake in there, let us celebrate this gift and have faith that we are in this together.