What is it Like to See the Color Red? (Am I My Brain?)
- Descartes, "Meditations: Meditation VI"
- Thomas Nagel, "What is it Like to Be a Bat?"
- Stephen Law, "The Consciousness Conundrum" (pdf)
This synopsis is considerably longer than usual. We're just past the midpoint of the semester, and this seems a good opportunity to trace the route we've taken to get here and highlight the mileposts we've passed along the way.
Our puzzles this semester have been leading one to the other in rapid, perhaps dizzying, succession. For consider,
1. We began the semester considering in what sense Socrates could be wisest man of Athens, since he knows nothing. Yet knowing nothing, he knows he knows nothing. Therein lies his wisdom: He alone of all the supposedly wise of Athens knows that he does not know, whereas they think they know, but in wrongly believing they know, deceive themselves. Socrates came to grasp this point by inquiring, critically, of the wisdom of the wise, who eventually convicted and executed him for it. To be sure, Socrates shies away from defending himself from what he himself deems the most serious charge, that he makes the weaker argument appear the stronger, and the stronger the weaker. He had not the tools, you see, since it was his pupil's pupil, Aristotle, who would eventually come to develop the science of reasoning we call Logic, which led us to ask,
2. What is the nature of truth-tropic language, such that language in certain forms (and not others) helps us to draw conclusions which are either likely true, in the case of (strong) inductive arguments, or guaranteed to be true, in the case of (sound) deductive arguments? How does the logical structure of an argument bear on its (deductive) validity, such that having certain structural features suffices for validity, regardless of the content of the propositions so structured? To answer these and other questions we developed a modest logic, the Propositional Calculus, and along with it two definitions of validity, which also serve as tests of validity: Truth Tables and Analytic Tableaux. We discovered we can analyze arguments for their truth-tropic properties, which led us to ask,
3. What is the nature of truth-phobic language, such that in some argumentative contexts language can seem truth-phobic, but in fact it leads us astray? Here we considered a number of the kinds of deliberate confusions the malicious can drop into language which only serve to mislead us, cloud our reason, or otherwise foil our earnest attempts to get at the truth. These fallacies, as we called them, were frustratingly ambiguous, in some contexts leading us towards the truth, as when an expert's authority is germane, and sometimes leading us away from the truth, as when it is not. We confronted the possibility that we cannot always determine which is which in the fog of language, which led us to ask,
4. Are there limits to human creativity and reason, beyond which we for whatever reason cannot go? Here we took up three paradoxes, which seem to have no solution so far as we could discern. Our trouble was this: The way in which puzzles confound us, the feelings of confusion and perplexity we had, is exactly the same experience of confusion and perplexity we have when we face a paradox. So how do we know whether an apparent paradox is not simply a puzzle we have yet to correctly analyze to discover the solution? (Since philosophy is all about asking such puzzling questions as this very question about puzzles and paradoxes, we do well to bear the limitations of our own human reason in mind as we take an altogether too brief tour of them.) We found that in the project of discerning (mere) puzzle from paradox, understanding the question becomes absolutely critical, which led us to ask,
5. Arguably the most fundamental question one can ask, the riddle of existence: Why is there something and not nothing? Looking around the world, we find only contingent beings--that is, beings whose explanation for being invokes other beings. What explains you? Your parents! What explains them? Their parents! And so on and so forth... but for how long? Surely the series of contingent beings cannot go on forever. There must be a necessary being whose existence is explained not by reference to some other being, but by reference to itself alone. Or, even if there could be an infinite series of contingent beings, what explains the series itself? And there we hit a wall, because either the series explains itself, or there is a necessary being whose existence explains the series' existence. In either case, we face the difficulty of explaining how a being (the series, or the necessary being) can be self-explanatory. Yet drawing on a necessary being to explain why there is something and not nothing invites (obviously) speculation about God's existence, which led us to ask,
6. Does God exist? Here we considered two arguments for the existence of God and one against. The Teleological Argument for the existence of God finds in the astonishing complexity and wonder of nature a level of function or purpose that seems to escape explanation by purely mechanical processes. Thus the complexities we encounter seem designed to us, which leads one naturally to wonder about a designer. Unlike the Cosmological Argument we took up last time and the Teleological Argument this time (both of which we say are a posteriori, or depend on observable phenomena we find in the world), the Ontological Argument is a priori, requiring no experience of the world, but only a careful consideration of the idea of God as the being than which none greater can be conceived--and surely, the argument goes, such a being must exist, since if it were merely a concept, it would not be the being than which none greater can be conceived! Of course, closely examining the presumed qualities of God (omniscience, omnipotence, and omnibenevolence) resulted in a rather daunting argument against the existence of God: The Problem of Evil. For if God exists and is all of those things, then evil could not exist. Yet evil surely exists. To be sure, we found cogent responses to all of these arguments. That is, we could extract valid arguments in each case, so our question in each case was: Is it sound? Are all the premises true? Invariably we found questionable premises. Our investigation into the existence of God was left an unsolved puzzle, which led us to ask,
7a. Should intelligent design as the Teleological Argument infers be taught alongside evolutionary theory in schools as a scientific alternative? Which question immediately led us to ask,
7b. What is a science? That is, how do we discriminate between genuine sciences like physics and biology, pseudo-sciences like astrology and palmistry, and (apparently) proto-sciences like alchemy and geo-centrism? We pointed to the logic of scientific theory, noting that a theory connects its laws to its empirically testable hypotheses via deductively valid arguments of the sort we have been studying. Since a valid argument can have a true conclusion and one or more false premises, a hypotheses confirmed by experimentation tells us nothing about the truth of the theory. No scientist can ever prove a scientific theory true! Yet since a valid argument cannot have a false conclusion without also having at least one false premise, a disconfirmed hypotheses serves to show us the theory (or, at least, some part of it) is false. The upshot is that scientists are never trying to prove their theories true--they cannot!--when they conduct experiments. Instead, they seek to prove them false. Should every attempt to prove a theory false to date fail, we do not say the theory is true. Instead, we say it is well-confirmed, which is frankly the most we can hope for with science. Following this line of reasoning, we reject as pseudo-scientific those endeavors which cannot be falsified. Genuine sciences always admit of falsification, of test by the tribunal of experience, to paraphrase the philosopher W.V.O. Quine. So maybe we shouldn't teach intelligent design alongside evolutionary theory in schools, going back to our original question, which led us to ask,
8a. Why are people so insistent on involving God in school? Our charitable answer was that they fear pupils will have no moral compass with which to guide their lives, which quickly led us to ask,
8b. Can we be good without God? If one says otherwise, then (generally speaking) one is adopting a very common view of what it is to be good. Namely, to be good is to conduct oneself according to God's commands. This seems simple enough, predicated as it is on the proposition that God's will determines morality. In making this assumption, however, we confront a devilish dilemma: Is it good because God commands it, or does God command it because it is good? If the former, being good could amount to anything, since in any case God commands, He, She, or It could have commanded otherwise. Moreover, the fact that God didn't happen to command otherwise tells us nothing unless we insist on God being perfectly good, yet God being perfectly good on this alternative just amounts to God doing what God says, which is meaningless. If the latter, and God commands thus and so because it is good, then God's will has nothing to do with morality, and we can be good (indeed, must be good!) without God. Yet the conclusion that we can be good without God says nothing about whether we will be good at all, which led us to ask,
9. Why should we be good? The usual story is that being good itself is merely an instrumental good. There's nothing good in itself about being good. What's good about being good is the rewards one hopes to receive and the punishments one hopes to avoid. Being good is merely useful as a way to seek rewards and avoid punishments. This, naturally, is a very old story. The very idea of heaven and hell is a way of holding out the prospect of eternal reward and eternal punishment, for example. As we saw with the Ring of Gyges, however, it is possible to reverse rewards and punishments. We imagine a very bad man who, using the ring, is perceived as good and enjoys all that comes from being bad and the rewards due goodness. We imagine a very good man, perceived as bad, who suffers all of the punishments of badness and none of the rewards his goodness merits. What is intrinsically good about being good, regardless, that is to say, of rewards expected or punishments avoided? Complicating matters is the fact that goodness (or badness) seems not to be entirely a matter of choice or even character. Instead, circumstance has a lot to do with whether ordinarily decent, unexceptional people become moral monsters, on the on hand, or moral heroes, on the other, which led us to ask,
10. Can we be morally responsible at all? That is, being held morally responsible (praiseworthy or blameworthy, as the case may be) seems to presuppose (among many other things) the capacity to have done otherwise. Yet as we saw in considering the problem of freedom of will, either we're caused to act as we do, in which case we could not have done otherwise, or we're not, in which case our actions are random and inexplicable. In either case, it seems we could not have done otherwise, for we are either the mechanical clock ticking away, or the spring careening off the wall and landing, say, in the coffee. Whether the universe is fundamentally deterministic or not, it seems irrational to hold one another morally responsible inasmuch as there seems no room in it for us to have capacity to have done otherwise, which led us to ask today,
11. Are we simply the sum of our neurological mechanisms, or is there more to the mind than simply the body and its central nervous system?
We must grant that the mind and the body appear to be very different kinds of things having very different kinds of properties. Descartes, swayed by such considerations, argued that the mind and the body are distinct, but causally interacting, substances. That is, he claimed that mind is an entirely different kind of substance than body, and he bridges the chasm between the two by asserting that physical events cause mental events and mental events cause physical events. Nevertheless, mind and body are distinct substances. How, then, do they interact? Solving this problem leads Descartes to do a lot of hand-waiving, some of which involves the pineal gland. In the end it is not at all clear that Descartes has a solution to the problem of how mind and body, conceived as distinct substances, causally interact.
An alternative to dualism is physicalism, the view that every mental state is some physical state. There are different ways to understand physicalism, but the one that has come to dominate modern cognitive science is known as machine functionalism, or the view that the mind is to body as the software is to the hardware in a computer. The mind is properly understood, on this view, as the functioning of the neural mechanisms that together constitute the central nervous system. According to this view, we really are (in a way) the sum of our neural mechanisms.
Yet just as a mechanical watch, a digital watch, a klepsydra, a sundial, a sand-timer, and an atomic clock can all serve the same function and tell time, surely we ought to be able to construct out of other parts (maybe computer parts themselves!) a device with a mind--an artificial intelligence, if you will, which, finally, led us today to ask,
12.Are there any capacities the mind has which escape altogether or in some way transcend the possibility of physical explanation?
So today we took up a puzzle which is so daunting it has been called the hardest problem in physics today. Consider that my subjective experience of smelling the freshly brewed coffee has a qualitative character--what it is like for me to smell the coffee--and a subjective character--what it is like for me to smell the coffee. The conscious state I am in while enjoying the subjective experience of smelling the coffee is the state it is because of the distinctive qualitative character of the experience, but it is my conscious state in the first place in virtue of my having it. We say that my capacity for having subjective experiences is grounded in my capacity to enjoy phenomenal consciousness and that the qualitative character of my phenomenal consciousness is in turn a result of the bits and pieces of colors, sounds, smells, tastes, touches--all the raw feels, in short--out of which my subjective experience of the world is constructed, which we call qualia.
For reasons we sketched in class, the problem posed by subjective experience is that there seems to be no physical basis for it to which we can point.
Setting Out the Problem
Phenomenal Consciousness is essentially the subjective character of experience. That is, phenomenal consciousness is what it is like to have this or that experience.
"[F]undamentally an organism has conscious mental states if and only if there is something that it is like to be that organism--something it is like for the organism."
Consider, for example, the bat. If the bat has subjective experiences, then there is something it is like to be a (particular) bat. But that something is wholly inaccessible to us.
There are facts accessible only from the first-person point of view of the organism. These facts consist of the facts of the qualitative character of subjective experience.
Materialism (Physicalism) proposes that every mental event is a physical event. The thesis of Reductive Materialism proposes that all the facts about mental events can be accounted for by facts about physical events.
|1||If Reductive Materialism is true, then any fact of mental events can be explained in terms of facts about the physical events to which they reduce.|
|2||It is not the case that any fact of mental events can be explained in terms of facts about the physical events to which they reduce.|
|∴||3||Reductive Materialism is not true.||1&2|
This is a very general way of presenting the challenge accounting for the phenomenon of subjective experience poses not just for understanding the computational basis of mind, but for any physical basis of mind whatsoever, whether computational or otherwise.
There is, you see, an important aspect to mental states: There is something it is like to have them. To want a glass of red wine is, on the one hand, to have a desire for the glass, and, on the other hand, to feel the pull, if you will, of the red wine. There is further something it is like to actually drink the red wine and satisfy the desire for it. These raw feels or qualitative experiences associated with mental states collectively fall under the problem of phenomenal consciousness. Yet why should there be anything it is like to be in a mental state of any sort?
The problem of phenomenal consciousness is usually cast as a problem for physicalism: At least some mental facts--facts about phenomenal consciousness, in particular--are arguably not physical facts; hence no version of physicalism, including computationalism, is true. Thus phenomenal consciousness is opaque to science, since science only trades in physical facts. Put another way, science cannot, apparently, explain how phenomenal consciousness emerges in a purely physical universe.
The problem phenomenal consciousness presents is as simple as it is devastating. As Nagel points out, no study of bats can ever reveal what it is like to be a bat. As much as we might learn about echo-location and nocturnal navigation, a bat's phenomenal consciousness is intrinsically perspectival: We can never know what it is like without already having that perspective, which we would have only if we were already bats ourselves.
This is the hard problem of consciousness: For creatures like us there is something it is like to be, just how is there something it is like to be them? How does a squishy lump of greyish/whitish matter have phenomenal consciousness insofar as it is not merely aware of things in its environment, it has rich subjective experiences of them as having various qualities?
Today we considered a couple of thought experiments designed to show that phenomenal consciousness is not reducible to brain states or, really, any physical state whatsoever.
|The Knowledge Argument|
|1||If Physicalism is true, then it is not possible to know all the physical facts without knowing all the facts.|
|2||It is possible to know all the physical facts without knowing all the facts.|
|∴||3||Physicalism is not true.||1&2|
Fred is able to consistently sort tomatoes into two piles, because Fred is able to distinguish between two kinds of red (what he calls "red-1" and "red-2"). He calls the rest of us red-1 and red-2 color-blind, because we cannot distinguish between objects that are red-1 and objects that are red-2. Yet we can determine all the neurophysiological facts about Fred.
|The Case of Fred|
|1||We can determine all the physical facts about Fred, but we cannot determine what it is like for Fred to see red-1 and red-2.|
|2||If (1), then it is possible to know all the physical facts without knowing all the facts.|
|∴||3||It is possible to know all the physical facts without knowing all the facts.||1&2|
Mary is an expert in vision. She has, however, gained her expertise over black-and-white television while in a black-and-white room. Mary has never seen the color red, so she does not know what it is like to see red. What she does know are all the facts of neurophysiology pertaining to vision.
|The Case of Mary|
|1||Mary knows all the physical facts, but she does not know all the facts.|
|2||If (1), then it is possible to know all the physical facts without knowing all the facts.|
|∴||3||It is possible to know all the physical facts without knowing all the facts.||1&2|
The Knowledge Argument seems to force us to the unhappy conclusion that there is no physicalist account of the phenomenon of phenomenal consciousness. I say "unhappy" because the lack of a physical account of phenomenal consciousness entails we cannot build a mind: We have, after all, only the 'stuff' around us to use in building a mind; yet if these arguments are sound, no amount or combination of physical stuff will allow us to build a mind which enjoys phenomenal consciousness.
Thus much hinges on these arguments. No doubt this explains why the problem of phenomenal consciousness has been one of the most discussed problems in recent philosophy. Some of the best minds philosophy has to offer have been absorbed by it, and some physicists and neuroscientists have begun to notice the enormity of the challenge phenomenal consciousness presents.
Part of the appeal of the Knowledge Argument is surely the simplicity of its explanation. Our intuitions about phenomenal consciousness are teased-out and bolstered by two clever thought experiments, the case of Mary and the case of Fred, which provide us something like a graphic-novel approach to philosophy. Putting it that way is not to denigrate but to compliment: One of the reasons Jackson's original article, "Epiphenomenal Qualia", has generated so much discussion is the accessibility and clarity of the problem he describes.
In the forward to "There's Something About Mary: Essays on Phenomenal Consciousness and Frank Jackson's Knowledge Argument" (Peter Ludlow, Yujin Nagasawa, and Daniel Stoljar, eds., Cambridge, Mass: MIT Press, 2004), Jackson offers this brief on his argument:
There are two main parts to the knowledge argument (in the form in which I advanced it; there have been many versions of it): the part that says that complete physical knowledge is not complete knowledge tout court (or anyway not as far as the mind is concerned), and the part that says that if physicalism is true, it is. The final step is then modus tollens. The first part is the part supported by the plausibility of the contention that Mary would learn something about what the world is like on her release. As we might put it, she would acquire an enlarged view of the available dimensions of similarity in our world. Before her release, runs the first part, she knew a lot about how different people looking at ripe tomatoes typically were alike, both in themselves and in their relations to the tomatoes. She knew, for example, how the ripe tomatoes typically induced a tendency to use the word 'red' in such people, provided they were English speakers. After her release, she would realize that there was another dimension altogether to how they are alike, and to how they differ from people looking at, say, grass. The second part of the knowledge argument is the part where it is observed that because she knows all there is to know physically, this means that were physicalism true, there would be no dimensions of similarity instantiated in our world other than those she knows about in the room before her release. Therefore, physicalism is false.
In the same forward, Jackson repudiates what he formerly believed the argument demonstrated. Indeed, he is now confident the argument goes wrong somewhere, even if it is not clear where. As he puts it,
Although I no longer agree with the knowledge argument, I do think it has been, and continues to be, a major impetus to many important debates that have cast a great deal of light on some very hard problems in the philosophy of mind. In many ways, I which I could still accept it.
Let us expand a bit on the above case of Mary. Mary is the object of a sadistic philosophical experiment in which she is raised from birth in a black-and-white room. We might even imagine her being tatooed black and white herself to remove any possibility of her ever seeing color. We're not wholly sadistic. We give her a computer with which to learn things about the world. (You shouldn't have to ask: Of course it has a black-and-white monitor!)
Now let us suppose that the physics of color an the neurobiology of color perception are completed sciences. Thus all the physical facts about color and its effect on our neurophysiology are known. Mary, never having experienced color, uses her computer to become expert in these (completed) sciences. So she knows everything there is to know about the physical facts of color.
Now let's let her out of her black-and-white room. Just for fun, let's put a huge, juicy, ripe red apple on a table outside the door so it will be the first thing she sees on leaving the room. Surely she will learn something new, something she would not know before leaving the room: what it is like to see the color red. She will now know, to frame it as Jackson does above, that those seeing the color red are alike in a way she did not, and could not, have known before leaving the room. Yet she knows all the physical facts, so what she now knows is not a physical fact.
Broadly speaking, two responses to the knowledge argument have emerged corresponding to the two parts of the argument as Jackson described them above:
- Deny the proposition that "complete physical knowledge is not complete knowledge" (Jackson's own move, interestingly); or
- Deny the proposition that all knowledge is physical knowledge while maintaining that physicalism is nonetheless true.
The philosophical gymnastics involved in either response are complicated and fascinating. Suffice it to say that Jackson is correct: We learn much in coming to grips with the argument.
The current state of affairs is not, however, encouraging: There is no consensus on a final solution to the puzzle Mary presents. As puzzles go, it's a doozy.