Peter Carruthers has been blogging this week on the thesis of his new book, Human and Animal Minds: The Consciousness Question Laid to Rest. I mentioned Carruthers’ book in my post on global workspace theory (GWT), but didn’t get into the details. While I had been considering taking a fresh look at GWT, his book was the final spur that kicked me into action.
Carruthers used to be an advocate for higher order theories (HOT) of consciousness. He formulated the dual content version that I thought was more plausible. As an advocate for HOT, he seemed skeptical of animal consciousness. But in recent years, he’s abandoned HOT in favor of GWT: the idea that conscious content is the result of processes that have won the competition to have their results globally broadcast to systems throughout the brain.
Most GWT proponents will admit that it’s a theory of access consciousness, that it doesn’t directly address phenomenal consciousness, which usually isn’t seen as a problem because most people in this camp see them as the same thing, with phenomenal consciousness being access consciousness from the inside. In other words, the idea that phenomenal consciousness is something separate and apart from access consciousness is rejected.
Carruthers isn’t completely outside of this view, but his is a bit more nuanced. He sees phenomenal consciousness as a subset of access consciousness, the portion of it that includes nonconceptual content, content that is irreducible, such as the color yellow. (Of course, objectively the content of yellow is reducible to patterns of neural spikes originating from M and L cones in the retina, but only the irreducible sensation of yellow makes it into the workspace.) This is in contrast to conceptual data, such as the perception of a dog, that is reducible to more primitive experience.
So Carruthers sees phenomenal experience as globally broadcast nonconceptual content, in humans. Why the stipulation at the end? He points out that phenomenal experience is inherently a first person account, in that discussing it is basically an invitation for each of us to access our own internal experience.
Asking whether another system has that same internal experience is asking how much like us they are. Other species may have processes that resemble our global broadcasting mechanisms, to greater or lesser extents, and the collection of competing and receiving processes may resemble our own, again to greater or lesser extent. In both cases, the farther we move away humans in taxonomy, the less like us they are.
Which means that no other species will have the exact same components of our experience. Whether what they have amounts to phenomenal experience, our first person experience, depends on which aspects of that experience we judge to be essential. In other words, there isn’t a fact of the matter.
I pointed out to Carruthers that this also applies to many humans, notably brain injured patients, whose global broadcasting mechanism or collection of competing and receiving processes no longer match that of a common healthy human. Carruthers, to his credit, bites this bullet and acknowledges that there isn’t a fact of the matter when it comes to whether human infants or brain injured patients are phenomenally conscious.
Carruthers’ overall point is that it doesn’t matter, because nothing magical happens at any stage. Nothing changes. There are just capabilities that are either present or absent. In his view, the focus on consciousness is a mistake. Broadly speaking, I think he’s right. There is no fact of the matter. Consciousness is in the eye of the beholder.
But it’s worth discussing why that’s so, arguably the reason why anything ever fails to be a fact of the matter: ambiguity. In this case, ambiguity about what we mean by terms like “phenomenal experience”, for it to be “like something”. “Like” to what degree? And what “thing”?
As soon as we try to nail down a specific definition, we run into trouble, because no specific definition is widely accepted. The vague terminology masks wide differences. It refers to a vast, hazy, and inconsistent collection of capabilities we’ve all agreed to put under one label, but without agreeing on the specifics. It’s like lawmakers who can’t agree on precisely what a law should say, so instead write something vague that can be agreed on, and leave it to the courts to hash out later.
And yet, I think we can still recognize the ways various species process information will be similar to the way we do, to varying degrees. As Carruthers notes, there is no magical line, no point where we can clearly say consciousness begins. But great apes are a lot closer to us than dogs, which are closer than mice, which in turn are closer than frogs, fish, etc, all of which are much closer than plants, rocks, storm systems, or electrons.
And there’s something to be said for focusing on systems that do have irreducible sensory and affective content that are globally integrated into their processing. This matches the definition many biologists use for primary consciousness. Primary consciousness appears to be widespread among mammals and birds, and possibly among all vertebrates and arthropods.
But primary consciousness omits aspects of our experience many will insist are essential, such as metacognitive self awareness or imaginative deliberation, capabilities that dramatically expand our appreciation of the contents of primary consciousness. Such a view dramatically reduces the number of species that are conscious, perhaps only to humans and maybe some great apes. Which view is right? To Carruthers’ point, there is no fact of the matter.
Incidentally, even primary consciousness gets into definitional difficulties. For example, fish and amphibians can be demonstrated to have both sensory and affective content, but the architecture of their brains makes it unclear just how integrated the affective contents are with much of the sensory content. Does this then still count as primary consciousness? I personally think the answer is yes since there is at least some integration, but can easily see why many might conclude otherwise.
What do you think? Is Carruthers being too stingy in his conclusion? Is there a way we can establish a fact of the matter we can all agree on? Or is the best we can do is recognize the partial and varying commonalities we have with other species?