Consciousness, Self, and the Prefrontal Cortex

cartesian-theater

There is a basic question that must be addressed when pondering the nature of consciousness, and that is: why have consciousness at all? The brain processes a great deal of information below the level of conscious awareness, from visual to auditory to tactile, and then the integration of all of these before they can be brought into conscious awareness. Yet conscious awareness itself seems much more limited in the amount of information that it can handle at a time—5 to 9 “chunks” of information, at a time, it would seem. So why rely on conscious awareness as heavily as we do? It certainly seems, at least from this angle, much less able than non-conscious processing—yet, given its apparent efficacy in raising humanity to the heights of culture and insight that we enjoy today, it surely has something essential to offer us.

The prefrontal cortex is the latest structure to appear in the evolution of the brain, and is the structure that shows the greatest development between humans and our closest biological relatives. Furthermore, it is known to mediate a great deal of the abilities considered distinctly human, such as planning, reflection, and empathy, all of which apparently require conscious awareness. Surprisingly, however, a vast abundance of the projections that the prefrontal cortex sends back to more primitive, sub-cortical structures are inhibitory—they function largely to suppress activity in these regions. In fact, this has led several researchers to rethink the concept of free will and, somewhat amusingly, refer to it rather as “free won’t,” in that we are mainly choosing what not to do, of all of the responses recommended by sub-cortical structures. And this is where we might find a reason for conscious awareness.

Consciousness relies on a crucial ingredient for dealing with the world in the way that the prefrontal cortex specializes in doing: it removes behavior from the moment-to-moment sensory perceptions incessantly presenting themselves to sub-cortical brain regions. Instead of constantly responding to each and every stimulus as it comes in, consciousness introduces a disconnect that allows reality apart from oneself to be treated as perceived, and thus distinct from the self and manipulable. Non-conscious responses don’t require perception in the same way that conscious processes do. In order to consciously ponder a course of action while planning, you need a virtual representation to work with, and in order to do that, you need some distance between yourself and the object being represented. Every day perceptions such as the visual field in front of you may function in a very similar manner: a stimulus presents itself, is processed by sub-cortical structures, and then a course of action is offered up to conscious awareness to be chosen or discarded by conscious reflection. There is a whiff of “opponent processing” going on in this narrative, something that comes up a lot in systems biology: two structures working in opposite directions in order to better center around a single desired outcome. Non-conscious, sub-cortical processing is largely reactive, leading to sometimes extreme, reflexive responses; conscious prefrontal processing, on the other hand, divorced from the constant demands of the environment, is more receptive to multiple courses of action, but can sometimes leave us unable to settle on an alternative. With the two of these working with opposing aims, however, behavior that is reactive enough to survive, but receptive enough to be a functioning member of society, can be attained.

This is far from a coherent theory or hypothesis, but the parallels between the roles of sub-cortical and non-conscious processes on the one hand, and prefrontal and conscious processes on the other, along with the connections between the two, are surely going to be important in mapping human consciousness.

Advertisements

Memory and Personal Identity

Today in metaphysics I had to write up an impromptu response to the question: “Is memory important to Personal Identity?” I only had thirty minutes to write and not much time to prepare, so it’s a little rough, but I am nonetheless satisfied with what resulted, so I’ve reprinted it here:

———————————————————————

Memory is not vitally important to personal identity. This is not to say that it is not useful to our everyday determination of “who’s who,” more on that later, but we can show that it is possible to maintain personal identity without maintaining memory.

Consider the case of Tom, or case 1. Tom is about to be tortured. But the torturer, being a slightly nice guy, proposes the following: before torturing Tom, he will wipe all of Tom’s memories. Should this make Tom feel any better? “Of course not,” I would expect Tom to reply, “I’ll still be tortured, I just won’t remember that it’s still me who was tortured!” So we are not making the situation any better—we are actually making it worse! Not only are we going to torture Tom, we are also going to turn him into an amnesiac! If this case is persuasive, then we have shown that memory is not necessary for personal identity.

But I think we can go one step further and show that it is not sufficient either. Consider case 2: Exactly the same as before, except this time we will not merely erase Tom’s memories, but instead transfer them to another body, say, Jane’s body. Now, who would Tom, pre-memory transfer, want us to torture, Tom’s body or Jane’s body? I think that, thinking only of himself, he should want us to torture Jane’s body, and here’s why: this case is no different from the first. If removal of memory is not enough to remove personal identity, as the case 1 seems to show, then how could implantation of memory create a person? If it were able to do so, then we would have two “Toms” at the end of the procedure: one amnesiac Tom in Tom’s body and one “normal” Tom in Jane’s body—but this seems to be obviously mistaken, Tom can only be in one place at a time! So which Tom is illusory? Well, if we stick with our judgment for case 1, then it seems we have to say that the “Tom” in Jane’s body is the illusory one. It’s not really Tom, Jane just thinks that she is Tom. Tom is still in Tom’s original body. If all of the preceding is true, then we have shown that memory is neither necessary nor sufficient for personal identity.

At this point, it would be prudent to evaluate just what it is that we are saying, and just what we are not saying. The preceding argument aims to show that memory is not important from a metaphysical standpoint—but this says nothing about the epistemic standpoint. In real life, memory is often all that we have to go on for determining personal identity. How do I know that I am the same person as I was last week? Because I have the memories of what I did last week! If we agree with the preceding argument, though, it would seem as if we were contradicting ourselves. We cannot determine our own identity based solely on our memories. Well, okay, maybe we can’t, for all we know, some mad scientist  implanted some false memories into my brain while I slept, and I am not who I think I am, this is not outside the realm of possibility. But it seems pretty unlikely—so, inferring to the best explanation, that barring unusual circumstances memory goes hand-in-hand with personal identity, I conclude that I am most likely the same person as my memory tells me I was last week. It’s not certain, but it is very likely. It’s important to note here, though, that these are all epistemic worries. They tell us nothing about the metaphysics of personal identity. I can use memory as a good “indicator” of personal identity, so in that sense it is very important to our conception of personal identity, but that does not mean that the two are inextricably linked. As an analogy, if I hear a dog bark, I usually infer  that a dog is nearby, but for all I know someone is merely playing a recording of a dog’s bark and there is, in fact, no dog nearby. Personal identity refers to the dog, and the recording of a bark is the memory of Tom in Jane’s body.

———————————————————————

There’s a technical point about memory that I did not have time to address in my original response, but which I want to bring up here. In order for something to really be a memory, it has to stand in a causal relation to the event that it recalls—that is, the event that it recalls has to itself be what caused the memory to exist. So in this sense, I probably have many things that I would call “memories” in my head that are not truly memories. Perhaps I am misremembering something, or perhaps I have heard a story of my childhood so many times that, even though unbeknownst to me my own memory of the event is gone, I have recreated the scene in sufficient detail for me to be able to picture it vividly. On this definition of memory, Jane never really had memories of Tom’s life. They felt like memories to Jane, but since they were not caused by the events in Tom’s life, but rather by the torturer’s memory implantation, they are not, in this strict sense, true memories. If you were to adopt this more nuanced view of memory, then a memory theory of personal identity may be more plausible. Unfortunately though, you can still show, as per case 1, that memory is not necessary for personal identity.

Personal Identity, Brains and Fission Cases

When it comes to personal identity, the following question needs answering: what does it take for person A at time 1 to be the very same person as person B at time 2? Perhaps more clearly, right now I am sitting in front of my laptop, typing this post. In, say, ten minutes, there will be a person sitting in front of this laptop, publishing this post. What has to be true of that person for us to say that that person, ten minutes from now, is me? Now, it seems to me that this is a rather strange question for us to be asking, and it may be that we are simply confusing ourselves when we ask it—but let us assume for the present discussion that it is a coherent question to ask, as many contemporary philosophers certainly have, so that we may examine one answer that has been suggested.

The brain view, a slightly more refined version of the body view, says that in order for us to determine whether or not we have the same person at two different time points, we need to determine whether or not they have the same brain (accordingly, the body view says that we need to track the body—but this, for obvious reasons, can lead us astray). Neuroscience tells us quite assuredly that the brain is, in some way, the seat of what makes a person a person. Inside the brain lies all of the machinery required for memory, learning, personality, and all of the other traits and abilities that ordinarily allow us to identify the people around us as being who we think they are. The problem, however, with simply examining these surface-level features is that they can be mimicked, they can be replicated in a copy, leading us to the false conclusion that the copy is the real thing, just as if we were merely to examine outward body features. If we track the causal history of the brain itself, however, we should be able to figure out who is who in a more concrete manner.

So far, so good. We have what seems to be a good thesis: track the brain, track the person. Now we would like to refine the view even further. Is the whole brain necessary for personal identity, or only part of it? We know that in many respects the brain is redundant, having two more-or-less copies of each cortical structure—might we only need half of a brain to maintain personal identity? We are not necessarily constrained by specifics here, so let us make a simplifying assumption: each cortical hemisphere is indeed an exact mirror image of the opposite cortical hemisphere (there seems to be nothing in nature that points to this being impossible).

Now consider the following thought experiments: At time 1, Fred is a normal, healthy person. At time 2, he suffers a sudden, catastrophic loss of one of his cortical hemispheres. We now need to ask ourselves, is Fred-2 the same person as Fred-1? Common sense seems to tell us that he is, so perhaps on the brain view one hemisphere is indeed sufficient for maintaining personal identity. Now let us start over: at time 2, instead of Fred simply losing half of his brain, imagine that, instead, his brain is removed from his body, half of it is destroyed, and then the remaining half is implanted into the brainless body of Steve. After sufficient recovery from the operation, Steve’s body wakes back up—but who has woken up? On the brain view from before, we would have to say that Fred wakes up in Steve’s body. After all, it is the brain, not the body, that truly matters here. Alright, one more twist. Imagine this time that at time 2, Fred’s brain is again removed from his body, but this time the left half of brain is implanted into one brainless body, while the right half is now implanted into a separate brainless body. I have provided a schematic below to clarify the situation:

lY4c1

 

 

We have one body, Lefty, and another body, Righty (the names merely allow us to keep track of which body gets which half of the brain). After sufficient time for recovery, both bodies awaken. Now we again have to ask: who is waking up in each body? We have three options here, it would seem: 1) Fred, the same Fred as Fred-1, is waking up in both bodies; 2) Lefty is Fred-1, but Righty is not (or vice-versa); or 3) Neither of these people who wake up are Fred-1, Fred-1 died when the transplant took place. It we remain faithful to our previous conclusions, it would seem that we have to go with choice 1: both Lefty and Righty are equally Fred-1. But this can’t possibly be the case! How can Fred be in two spatial locations at the same time? Is he experiencing both bodies’ perceptions at the same time? If so, how? This simply seems to be impossible, and I am inclined to agree with this. Okay, how about option two? Perhaps Fred-1 is now in Lefty’s body—but wait, what reason do we have for him being in Lefty’s body versus Righty’s body? Both bodies, as per our simplifying assumption, have exactly the same half of a brain as the other. So much for option two. We’re now left with a final choice: neither Lefty nor Righty are Fred-1. Fred-1 is dead, no longer in existence.

But if we accept this conclusion, and it seems that we must, what does this say for our first two cases? Is Fred-2 no longer Fred-1 simply because he has lost half of his brain? There’s something that tells us that he has to be the same person. Obviously he is not exactly the same, he now has half of a brain, but intuitions seems to maintain that he is nonetheless still the same person—are we wrong?

I am not sure where exactly I stand on this issue at the moment, but I do have one thought that I think is promising. If the brain is truly duplicated in each hemisphere, but only one is needed for personhood, might there have been two people in Fred-1’s body (that is, one per hemisphere)? We may want to redefine a “person” as two of these “hemisphere-persons” in this case, which leaves us with the following: Fred-1 did not die, but half of him did. Fred-1, in the strictest sense, no longer exists, but part of him does. Returning to the final case, then, none of our original options really suffice. Instead, we would say that half of Fred-1 is in Lefty, while half of Fred-1 is in Righty.

This may not seem to be too strange of a conclusion, seeing that each body indeed has half of a brain, but when it comes to identity, it is at least a little weird. We like to think of personal identity as a 1:1 relation. You either have a person or you don’t, nothing in between. It’s not the case that after ten years of life, I am only 80% me. No, I am still me—the same person as I was before, even if my desires, beliefs, etc. have changed a little or a lot in the intervening time period. Should we re-evaluate this intuitive answer?

 

 

Brief Thoughts on the Analogy with Vitalism

It is sometimes asserted that consciousness and many of its aspects are illusory. Some of this, I believe, may turn out to be true. For example, our naive conception of conscious will seems to be at least partially illusory (see here and here for my views on that). Some, however, claim that even such fundamental notions as our sense of self are illusory, finally claiming that consciousness as a whole will one day be explained away as an illusion. I, as you may have guessed, take serious issue with this claim.

A common line of argument taken to support the claim draws an analogy between the present situation and the endeavor to explain life some hundred years ago. There were, in those days, the vitalists. These were the theorists who could not imagine that dead matter and its interactions could account for all that there is to complex life—there had to be something extra, some elan vital, or life force, underlying all of this. Even if we explain heredity, reproduction, growth, etc., we will still be missing something—namely life itself. We now know that they were wrong, dead wrong, and that, in fact, there is simply dead matter interacting in specific ways that leads to the formation of complex, living organisms.

Now take the assertion made by many contemporary philosophers of mind: even if we explain vision, intelligence, emotion, etc. (i.e., the so-called “easy problems” of consciousness), then we will still be missing something—namely consciousness itself. If we explain all of those things that can be worked out computationally, then we will be missing the very thing that we sought to explain in the first place: subjective, conscious minds. But is this necessarily the case? Might consciousness simply fade away the more and more we know about these other processes? Maybe consciousness is simply the elan vital of philosophy of mind, say proponents of this analogy.

This could not be further from the truth. When it came to explaining life, a higher-level property such as the elan vital was postulated to account for something that we did not know the cause of: the difference between living and dead objects. When it comes to consciousness, we are not postulating something above and beyond what we already know. In the words of Descartes, “I think, therefore I am.” His dualism may have been misguided, but he was spot on in stating that there is nothing that we know with more certainty than that we are conscious, that we are our own self. In this way, the analogy is deeply flawed. Something can only be explained away if it was postulated to explain something that we know to be true. Consciousness, however, was never postulated. Instead, it was the very phenomenon that we set out to explain. We may be wrong about the details, and in all likelihood we are, but we are not, as a matter of fact, wrong when we state that we are conscious beings, that consciousness is a real, existing phenomenon that begs explanation in its own right.

Predictability, Determinism and Free Will

In ordinary language, the concepts of predictability and determination are taken to mean roughly the same thing: if something is predictable, then it has definite causes that determine it to be the way it is; conversely, if something has definite causes that determine it to be the way it is, then it is, in principle, predictable. In philosophy, however, these are distinct concepts. Something that is deterministic need not be, in principle, predictable, and again, conversely, something that is predictable need not be deterministic. I will use two examples to illustrate this point, remarking on the second statement first, as I think it is the less significant of the two.

First, we will examine quantum physics. We would like quantum physics to be deterministic and may even have good reason to suggest that it must be, but at this point, we cannot say that with any certainty that it is, in fact, deterministic. Still, even supposing that it is not deterministic, we can use probability based models to predict, with sufficiently high precision, what the results, or outputs, of a quantum system will be.

Second, and I think more importantly, we can look to the universe at large. If we assume that the universe is entirely deterministic—which again we cannot say with any certainty but have good reason to think that it is—then it does not follow that everything in the universe need be predictable, in principle. We could say that a super-being with all the information about every single particle and its momentum could, theoretically, predict the state of the universe at any given time, but if we add materialism to this deterministic universe, this suggestion becomes meaningless. So let us think of it this way: if we want to model a system, we can represent each part of that system in a computer program. In order to do this, we will need to map each bit of information onto its own bit of computer coding, in a one to one fashion. Put simply, if we want to model a system with 10 components, we will need 10 bits of computer code, each mapping one of the ten components*. But we cannot do this with the universe at large. By definition, we need to map every single particle in the universe onto its own bit of computer coding—how can we do this? We have already exhausted every single particle in the universe by defining our system to be modeled—we simply have no particles left that could make up the computer coding for our program. Going back to our system of 10 components: if our universe only contains 10 particles, then we cannot model this system except by using the system itself as the model, but then we aren’t really modeling it, we are just watching the original system play out naturally. In this way, we can see that, even if our universe as a whole is deterministic, we still cannot, in principle, predict everything that is going to happen, because we, in principle, lack the means to do so, excluding the existence of non-physical super-beings.

To drive this home, I am going to borrow a quote from Richard Feynman:

It’s again this chess game business. If you were in just a corner where only a few pieces were involved, you could work out exactly what’s going to happen. And you can always do that when there’s only a few pieces, so you know you understand it. And yet, in the real game, it’s so many pieces you can’t figure out what’s going to happen. So there was a kind of hierarchy of different complexities. It’s hard to believe—it’s incredible, in fact most people don’t believe—that the behaviour of, say, me, one yack-yack, and you, nodding and all this stuff is the result of lots and lots of atoms all obeying these very simple rules.

To conclude, in a way, I want to remark on the relation between determinism, predictability, and our naive conception of free will. Part of the naive conception of free will is that we can, in principle, act in unpredictable ways. It simply is not the case that someone external to me could predict my own own behaviour with perfect precision. Often, the view of determinism, and its lay-equivocation with predictability, is seen as an attack on this conception of free will. But using the argument above, we see this need not be the case. We will never be able to predict the state of the universe at large, and if we cannot do say, we may always be misdefining one of the variables that we use to predict a local, closed system (i.e., for the purpose of this example, a human brain). Determinism does, in fact, have profound implications for free will if it turns out to be true, but they are much more subtle than they might seem at first glance.

*This is an oversimplification. We would also need computer coding for each of the laws describing the relations between the different components, but we will see that we need not even invoke these to illustrate the point.

Indeterminism: What It Is, and What It Isn’t

I want to briefly remark on the concept of indeterminism:

It is sometimes stated that we have two choices: determinism in the strict sense, or probabilistic indeterminism. This could not be further from the truth. Simply because a system is not strictly deterministic does not mean that the only other option is probability, or “lawlessness,” as some have put it. Agent causation is another option (note: it is possible to redefine and subsume agent causation under one of the two former options, but it is not necessary to do so).

That said, it seems to me that the attempt to formulate the problem in this way is not mere carelessness, but, in fact, a deliberate attempt by strict determinists to belittle their opponents. Most anti-determinists do not propose that simple probabilistic indeterminism is the right way to go, but rather endorse some form of agent causation, as mentioned above. If you can convince your audience, however, that your opponents are arguing for nothing more than “simple indeterminism” (i.e., the probabilistic form of indeterminism), then you avoid having to actually take on your opponents arguments, seemingly strengthening your own position.  It is worth noting that some of the arguments that get labeled as indeterminism in this way are actually only arguments against the strictest form of determinism.

This kind of rhetoric is highly counterproductive, and should be attacked whenever it is identified.

On Schools of Thought in the Sciences

Joseph Schumpeter:

A man expressing his political will and the same man expressing a theory in the lecture hall are two different people . . . Especially in my case, ladies and gentleman, because I never wish to conclude. If I have a function, then it is not to close, but rather to open doors, and I never felt the urge to create something like [my own] school [of thought] . . . Quite a few people are upset about this point of view, because there are [many] who feel they are the leaders of such schools, who feel like fighters for total light against total darkness. That gets expressed in the harsh criticisms that one school levies against the other. But it doesn’t make any sense to fight about these things. One shouldn’t fight about things that life is going to eliminate anyhow at some point. In science momentary success is not as important as it is in the economy and in politics. We can only say that if something prevails in science, it has proven its right to exist; and if it isn’t worth anything, then it’s going to die anyway. I for myself completely accept the verdict of coming generations.

 

Brief Thoughts on Res Cogitans and Res Extensa

Descartes ultimately distinguished between two sorts of substances: those that are extended in space (res extensa) and those that are purely mental (res cogitans). However, physics now tells us that, at their most basic, all those “things”—or “particles,” if you will—that we once labeled as extended are not really extended at all. Atomic and subatomic particles are more accurately described as points of localized mass-energy, rather than spheres with discrete spatiotemporal dimensions. In light of this, Descartes’ dilemma can be, in a way, resolved: He viewed mental contents as distinct and incapable of scientific description because they lacked physical extensions that could be measured. We have now seen, however, that the very “things” that we once praised for their apparent extension (i.e., their property that we believed allowed them to be studied scientifically) are not really extended at all. Thus, it could be argued that the lack of physical extension is not sufficient for the exclusion of res cogitans, or the mental, from scientific inquiry.

(Note: I am not denying any distinction between ordinary physical events and mental events. There certainly is a distinction. I am merely proposing that this view of the distinction may be false, though this is certainly not new.)

 

Reblog: Problematical Property Dualism

 In the philosophy of mind, non-reductive materialism is a position taken by people who are convinced that there are non-material properties, yet still want to maintain a monistic ontology, while distancing themselves from idealism. Generally, this position entails a substance monism combined with property dualism. So, there is one kind of substance in which physical and mental properties are both instantiated. A brain would then be composed of a material substance which has both mental and physical properties.

This view is usually combined with the thesis that mental properties supervene onto physical properties, but are not reducible to physical properties. So, any substance S that has mental property Q will have physical property P; and it is necessarily the case that if  S has Q then is also has P. That is the general supervenience thesis held by non-reductive materialists who endorse property dualism.

There is a problem with this account of the mental, though. If there was a certain time in the past when there were no mental properties (a time before the existence of life complex enough to instantiate said properties), then there must be a time at which mental properties instantiated. It seems as though there’s literally a moment when mental properties didn’t exist, then they were ‘zapped’ into existence by whatever it was that instantiated the mental properties. It seems very implausible that such an account is true, given a monistic, materialist ontology. However, on substance dualism, the existence of non-material/non-physical properties like the ones endorsed by the property dualist is a plausible possibility. So, the moral of this story is that non-reductive materialism doesn’t seem as plausible as a substance dualism, given the existence of non-physical properties. If the materialist doesn’t find substance dualism plausible for the many reasons many philosophers of mind do, then the materialist may want to bite the bullet and give up his commitment to non-physical properties (unless he or she wishes to become a substance dualist).

My thoughts are re-printed below:

If I agreed that mental states had to “zap in” at some point in the past, then I would find this objection more appealing. That said, property dualism does not require that this occur. A more faithful property dualism would say, rather, that some form of “phenomenal character” existed at all points in the history of the universe, but this is not to say that it has to be recognizably “mental,” as we think of it today. The distinction between “physical” and “mental” is irrelevant to the discussion of property dualism—and philosophy of mind in general, I think, as everything mental is, so far as we can tell, necessarily physical is some way*—it is the distinction between objective and subjective that is most important. Each side of this more refined distinction has fundamentally different tools of explanation, and this is what I think of as a true property dualism.

*for support, I rely on a simple principle from Christof Koch: “No matter, never mind.”

via Problematical Property Dualism.