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|Sun, 02 May 2010
There is an old philosophical chestnut that says that the mind is to the brain as digestion is to the digestive tract. The underlying thought is clear: why should we regard the mind as something "special," over and above the brain, when we wouldn't regard digestion as something over and above the digestive organs?
The best reply to this chestnut is simple but surprising: digestion is something over and above the digestive tract. Your digestion - what you refer to when you say things like "I have a slow digestion" or "my digestion is good today" - is not merely part of your digestive tract. Instead, it is a feature of your digestive tract. It is what philosophers call an abstract entity. A feature of a thing is not identical to the thing. Thus, your digestion is not identical to your digestive tract - for the same reason that the mass of an electron is not the same as an electron, or that the shape of a window is not the same item as the window.
The reason the digestion-digestive tract difference is unlike the mind-brain difference is that nothing interesting follows from the digestion-digestive tract difference. The fact that the digestion is different from the digestive tract doesn't tell us anything new about the nature of digestion or of ourselves. It tells us no more than we already know when we admit that the shape of a window is not identical to the window. It is a near-trivial logical fact.
However, in the case of the mind (which is a feature or set of features of the brain), the difference between mind and brain does imply something interesting. Unlike digestion, the mind is associated in a distinctive way with a large domain of other abstract entities. These other entities are the contents of consciousness, which make up what we think of as our inner world. The fact that we possess this inner, abstract "world" has a drastic bearing on who we are as individuals and as a species. It makes the difference between a conscious observer and a mere nonconscious thing. Once we face the fact that this inner world exists, we realize that minds and selves are not just lumps of matter, even if they are only features of the brain. What is more, we cannot understand the mind without taking the inner world into account. If we ignore the contents of consciousness, we miss what is most essential to the mind.
With digestion it is different. Once we know the physical mechanisms of digestion, there is essentially nothing left to understand about the nature of digestion. Even if we admit that digestion is something distinct from the digestive tract, this fact doesn't help us understand digestion. We learn no more that way than we already knew when we realized that the mass of an electron is not an electron, or the color of a stone is not the same as the stone. The distinctness of digestion from digestive tract is, as I have said, a near-trivial logical fact. However, if we don't pay attention to the complex abstract features of the brain (specifically mental contents), then we don't really have any idea of what a mind is. We miss the important aspects of the mind.
This, in brief, is why the old analogy between digestion and mind fails.
The same argument works against any analogy that says "Why should I think my mind is distinct from my brain, when my [fill in name of body function] isn't distinct from my [fill in name of organ]?" The analogy fails for the same reasons.
posted at: 23:04 | path: /mind | persistent link to this entry
Thu, 19 Mar 2009
Think about your conscious experience as it is right now - everything that's going on in your inner mental world.
Now imagine the items in that world (sights, sounds, thoughts, the feeling of time passing, and so forth) disappearing one by one, until there's nothing left.
The result is a totally blank inner world - a mental world with no impressions or other contents at all.
What is left over? Just your consciousness - a "pure" consciousness, with no contents.
Now ask yourself a question: Is this any different from no consciousness at all?
What is the difference between a completely empty consciousness and no consciousness? Is there a difference?
This mind-bending question might seem purely theoretical. After all, how often does anyone have a pure, empty consciousness? Perhaps this happens sometimes during states near to unconsciousness, or during deep meditation - or perhaps not. In either case, empty consciousness seems to have little to do with our ordinary mental lives.
If you think about it further, the question of empty consciousness turns out to be important. This question might bear on the puzzle of the mind-brain relationship. Here's why.
If an empty consciousness is not possible, then the absence of conscious experience - the lack of a "stream" of impressions and other mental contents - is the absence of consciousness itself. If (as we usually suppose) the brain is responsible for creating these contents, then consciousness is entirely dependent on the brain.
On the other hand, if an empty consciousness is possible, then the absence of conscious experience might not spell the complete absence of consciousness. All the contents caused by brain activity could stop for a while, and some residue of consciousness - an empty consciousness - would remain. This empty consciousness would exist without any of the contents that correspond to brain activity. This raises the possibility that consciousness itself, in the form of an empty consciousness, might exist even in the absence of brain activity. In other words, maybe the mind is not simply reducible to the brain.
It is hard to see how scientific evidence could rule out this possibility. We can use scientific observations to study behavior, mental activity, and the processing of information in the brain. However, it is hard to imagine how science could test for the existence of a hypothetical "pure" consciousness in which no mental events happen. Suppose that a comatose person or a really good meditator were truly devoid of mental contents for a while. What observations would you do to tell whether this person was truly nonconscious or was in a state of empty, contentless consciousness? No set of scientific observations could tell the difference. Science studies consciousness by collecting and interpreting data about behavior (including verbal reports) and the functioning of the nervous system. The absence of behavior, and of the kind of brain activity associated with experiences, would point to the absence of any impressions, thoughts, feelings, or the like - any contents. However, if there were an empty consciousness, it would not be associated with any impressions or experiences. There is no compelling reason to expect that such a consciousness would be evidenced by any behaviors, or by any happenings at all. To use a colloquial English phrase, such a consciousness would be "nothing doing." Even if there were some type of observable brain activity associated with empty consciousness, how could a scientist decide whether this activity is associated with empty consciousness or with nonconsciousness? The subject would behave the same way in either case. From a first-person standpoint, neither empty consciousness nor nonconsciousness would involve any distinguishable experiences, so the subject would not have any grounds for making different reports. Thus, the question of the existence of an empty consciousness does not seem to be an empirical question at all.
Why should we even worry about empty consciousness? It seems like an outlandish possibility - the stuff of thought experiments at best. So why worry about this possibility? One potential answer comes from the strange world of mathematical logic. If we apply a little formal logic to the question of empty consciousness, we find that empty consciousness might have to exist, even if science cannot decide its existence one way or the other!
The most striking feature of consciousness is the existence of a way things seem - an "inner world" of facts that seem, to the conscious subject, to be true. If you are conscious right now, things seem a certain way to you. This "way things seem" is different from the objective, external world in many ways. Things can seem to be the case that are not the case (as when illusions occur), and many things really are the case that do not seem to anyone to be the case. The important fact is that there is a way things seem. For any conscious subject, a fact may seem to be the case or may not seem to be the case. These "subjective facts" of an observer's consciousness can be quite different from the facts of the objective world.
If you are conscious, you have a world of subjective facts. A "conscious" system that does not have such a world is not really conscious at all.
In my book From Brain to Cosmos, I used ideas from modern logic to explore the idea of subjective fact. I stressed the fact that consciousness defines what logicians call a modality.
The idea of a modality is somewhat involved. To show what a modality is like, I'll present two examples of modalities. (For more information, see a book or encyclopedia article on modal logic.)
Example 1: Possibility. Given any statement, you can create a new statement by adding the words "It is possible that" to the beginning of the statement. The new statement then describes what is possible instead of what is actual. For example, you could begin with the statement "There is a zebra in Moscow." From this you can form a new statement: "It is possible that there is a zebra in Moscow." This statement describes what is possible - what might possibly be true. This statement can be true even if there actually is no zebra in Moscow. After all, the mere fact that there is no zebra in Moscow doesn't rule out the possibility that a zebra might end up there!
The phrase "It is possible that" stands for an important modality - the modality of possibility. (Philosophers recognize several different kinds of possibility, but I won't explore those details here.)
Example 2. Pastness. For any statement, you can make a new statement by adding the words "It was the case that" to the statement. The new statement then describes what was true in the past, instead of what is true now. For example, you could begin with the statement "There is a zebra in Moscow." From this you can form a new statement: "It was the case that there is a zebra in Moscow." A less awkward and more grammatical way of saying this is: "There was a zebra in Moscow." This statement describes what was true in the past. This statement might be true even if today there is no zebra in Moscow. If today there is no zebra in Moscow, this doesn't rule out there having been a zebra in Moscow in the past!
The phrase "It was the case that" stands for an important modality - the modality of pastness. (Philosophers also recognize several other modalities having to do with time. The mathematical subject of "tense logic" makes use of these modalities.)
These two examples illustrate what a modality is. It's like a function that changes a statement into a statement of a different kind. Phrases like "It is possible that" and "It was the case that" change ordinary statements about the actual, present world into statement of other kinds - statements about possibilities and about the past, respectively. You can think of a modality as a way in which propositions can be true. A proposition (like the proposition that there is a zebra in Moscow) might be actually true - but it also might be possibly true, or true in the past. Even a proposition that isn't actually true can be "true" in one of these other ways.
Students of logic know of many different modalities. For our purposes here, the important thing is that seeming is a modality. The phrase "It seems to me now that" changes a statement about how things are into a statement about how things seem. If I say "It seems to me now that there is a blue door," I am making a statement about how things seem to me now - in other words, about my experience. This statement does not imply that there really is a blue door. Maybe I'm looking at a window and misinterpreting it as a door, or maybe I'm only dreaming about a blue door. Or maybe I really am seeing a blue door. In any of these cases, it seems to me that there is a blue door.
Now, what does all this talk of modalities have to do with the problem of empty consciousness?
Suppose that you really did attain a period of empty consciousness, like I described earlier. Would there be anything of your consciousness left over during that period?
Yes, there would. Even if you were having no experiences, there still would be a modality of seeming. There would be the modality of how things seem to you now - and this modality is an important element of your consciousness!
At any given moment during your period of empty consciousness, there still would be the modality of seeming to be the case for you now. This modality, like all modalities, is a way that propositions can be true. Even if there currently are no propositions that are true in this way (that is, nothing seems to be the case for you now), there still is this modality of seeming to be the case for you now. We still can make meaningful statements using this modality, even if nothing seems like anything to you. At very least, we can make the statement "It is not the case that it seems to you now that P," where P is any proposition at all. (Translation of this statement into plain English: "Nothing seems like anything to you now.") If you are conscious of nothing at all, then the statement "It is not the case that it seems to you now that P" is true, and describes an actual state of affairs. The statement could not be true in this way if the phrase "It seems to you now that" were meaningless. We know what this phrase means; it means the same as it meant before you went blank! Since that phrase still has its meaning, it follows that there still is a modality of seeming to be the case for you.
The bottom line is that there is something left of your consciousness even if your consciousness is absolutely empty! This "something" is a modality of seeming - a modality that is essential to being conscious. Even if you are not conscious of anything, there still is such a modality.
Of course, the modality is not an extra thing that exists besides your brain activity. The modality isn't a "thing" at all. It's an abstract logical item, just as are the other modalities like possibility and pastness. The important fact is that the modality of seeming does not go away just because your consciousness is empty. It continues being what it was before: just a modality.
Now we can answer the question that started this post. Is there any difference between an empty consciousness and no consciousness at all? Yes, there is! With an empty consciousness, there still is a modality of seeming, similar to the one that the conscious subject used to have when his/her/its consciousness was not empty. This applies to a subject whose consciousness didn't used to be empty, but is empty now. This situation is very different from the existence of no consciousness at all. If a physical system (like a rock) has no consciousness at all, then there is no modality of seeming associated with that system. There simply is no way that things seem for that object - not even an empty, blank, void way.
The fact that seeming is a modality suggests that there can, in principle, be an empty consciousness. There is no fundamental logical reason why an empty consciousness of some kind cannot exist. This is true because there is more to consciousness than just the contents of experience. There also is the modality of seeming - which is equally real whether or not consciousness has any contents.
Earlier I pointed out that if empty consciousness is possible, then consciousness has a feature that science cannot detect. Since empty consciousness is possible in principle, we are stuck with an interesting conclusion: that there is at least one fact about consciousness that science cannot know. This conclusion may seem dangerous to the scientific approach to nature, but actually it is not dangerous at all. Mathematics constantly deals with facts beyond the reach of scientific methods - for example, the fact that the Pythagorean theorem follows from the axioms and postulates of plane geometry. No one thinks that such formal mathematical facts are threats to science. The existence of an untestable feature of consciousness is a fact of much the same sort. It is a formal fact that becomes apparent when we apply modal logic (a type of mathematics) to the idea of consciousness. The facts of mathematics and logic are not threats to science - so the fact that empty consciousness is possible cannot be much of a threat either!
(Post updated slightly 10/18/2010 - one link changed)
posted at: 21:48 | path: /mind | persistent link to this entry
Thu, 07 Aug 2008
Is matter the only reality?
Is there anything in the cosmos beyond physical substances and forces?
Religious teachings usually answer "no" to the first question and "yes" to the second. Most religions claim that the universe contains spiritual things, or spirits, as well as physical things.
Most Western religions teach that God is a spirit. Most of these religions also teach that the human soul (the innermost self of a person) is a spirit.
Different religious teachings have different ideas about spirit. Many believers seem to think of spirit as a substance or stuff that is invisible but real. This substance supposedly can act on matter, producing the connection between body and soul.
This idea of spirit is interesting, but it has a serious drawback: it depends almost completely on faith.
Science hasn't found any need for the idea of spiritual items or substances that affect the material world. Instead, scientific findings suggest that the human brain "runs itself," in the sense that it doesn't need a separate soul to make it work properly.
Some people claim that parapsychology provides evidence of a soul, but this claim is extremely controversial.
Philosophy has more to say about the soul, but still not enough. Some rationalistic philosophers, such as the brilliant Descartes, have believed in a separate soul that influences the body. However, there is no widely agreed-upon rational line of argument for such a soul.
This leaves religious believers in a pickle. If they believe in spirit, they must rely on faith to support their belief. This makes their position unconvincing to those who don't happen to believe the same way. It also makes them vulnerable to atheists, who can simply laugh at the whole idea. Many modern atheists believe that science is the only important form of knowledge, and that faith should play no role in human thought. According to today's science-based antireligion, the mind is only a property of the brain, and therefore there is no soul and there is nothing spiritual in human nature.
This disagreement between believers and atheists rests partly on a mistake. Neither side seems to realize that the universe, as known to science, already contains items that are not physical objects. We don't have to believe in these items through faith; they are right there in the scientists' universe. What is more, if the mind is a property of the brain, then the human self is one of those remarkable items!
What are these remarkable items?
To find out, let's start with some basic observations.
The universe contains physical objects, like sticks, stones, stars and atoms. However, those objects never exist alone. Each physical object has properties: its shape, color, weight, and so forth. In other words, there are not just physical objects. There also are properties of physical objects.
A round stone has the property of roundness. A yellow star, which gives off mostly yellow light, has the property yellow. (Colors, after all, are properties.) A hexagonal snow crystal has the property of hexagonality. (It might not be a perfect hexagon, but still it has that property.) A diamond has the properties of solidity and transparency.
Roundness, yellowness, hexagonality, solidity, and transparency. These are not physical objects. They are properties of physical objects. They are not physical objects - yet we find them in the real world.
We don't live in a world of physical objects alone. We live in a world of physical objects plus their properties.
There are at least two kinds of items in the universe - (1) physical objects, and (2) properties.
Someone might object to this statement by arguing that properties really don't "exist" at all. Maybe there are only physical objects, and although we can talk as if the properties existed, it's only the physical objects that really exist.
Philosophers have been debating this question for thousands of years. The debate goes back at least to Plato and Socrates in ancient Greece. Philosophers have a name for this question (I'll mention it at the end of this post), but the name doesn't matter. The question is: Do properties really exist?
I think this question depends on confusion about the meaning of the word "exist." If someone asks whether properties exist, I'll answer the question with another question: What do you mean by "exist"?
If you think "exist" means "be a physical object," then the answer is no - properties don't exist, because they are not physical objects.
But if you think "exist" means "be something" (be any kind of item at all), then properties do exist.
I've written a philosophical paper on this subject, where I went into more detail and covered some points that I've skipped over here. The main lesson of that paper: We can safely assume that properties exist.
Properties exist for all practical purposes. The people who have to work with properties act as if properties are real. Colors are properties. No painter would dare to claim seriously that there are no colors in the world! No weather scientist would claim that ice crystals are not really hexagonal, just because some philosopher said the property of being hexagonal doesn't exist.
To insist that properties don't exist is to cut off the idea of existence arbitrarily - to limit existence artificially to concrete, individual objects like physical objects. If existence includes everything found in the universe, instead of just concrete physical objects, then properties exist. They exist as properties instead of as physical objects - but that's just another way to be real.
So properties are real for all practical purposes.
The world in which we live is not a world of physical objects alone. It is a world of physical objects plus the properties of physical objects. The properties are real items too - just as real as the physical objects, but existing in a very different way. The properties are not simply globs of matter and energy, like physical objects. Instead, they are qualities, features, or patterns in the physical world. They are real items that are found in physical objects, but that are different from physical objects. (For example, the property of roundness can be found in the sun, the moon, or a coin - but roundness is not the sun, the moon, or a coin. It's a property that all these objects have.)
What does all this have to do with spirit?
If properties are real, then spirit doesn't have to be a substance or stuff. Instead, it can be a property!
Instead of being an invisible substance, spirit might be a property of physical objects. As a property, it would be every bit as real as the redness of a sunset, or the hexagonal shape of a snowflake, or the brilliance and transparency of a diamond.
If spirit is a property, then the human brain could indeed have a soul. Science suggests that your personality or self is a property of your brain. If so, then that property might be your soul.
The nice thing about this idea of the soul is that it's hard for skeptics and atheists to attack. If you believe the soul is a property, then the skeptical argument that "the self is just a property of the brain" doesn't disprove the soul.
Skeptics try to debunk the soul by claiming that the self is "only" a property of the brain. The skeptics had better watch out! They are making a serious mistake!
The skeptics begin with the idea (suggested by science) that the self or personality is a property of the brain. From this, they argue that the soul is nothing - that there is no soul.
But wait a minute!
The skeptics say the self is a property of the brain. However, we have found that a property is not just nothing. In its own way, a property is quite real!
If the self is a property, then the self has a real existence of its own - just as real as if it had been a real ghostly substance. By saying that the self is only a property of the brain, the skeptics are admitting that the self is real. Worse yet for them, they are admitting that the self has a type of existence that goes beyond the existence of physical objects!
The skeptics might not realize they are admitting all this. However, if properties are real in any way at all, then this is where their "skepticism" leads.
Without realizing it, the skeptics have painted themselves into a corner, and admitted that people have souls of a sort!
Granted, these souls are a little different from what most religions teach. They are properties, not ghostly supernatural objects. But the important point is that they are real.
Once we admit that properties are real, then the skeptical view that the self is a property of the brain becomes almost the same as the religious belief that people have souls distinct from their bodies. The property of the brain that we call the self is an entity different from the matter of the brain - just as the yellowness of the sun is different from the sun itself.
So it appears that the skeptics and the believers are not as far apart as they seem.
Religious believers might have a big problem with this idea of soul-as-property. They might think that if the soul is a property of the brain, then the soul cannot be immortal. Skeptics often use this argument to debunk the idea of an afterlife: if the self is a property of the brain, then it must cease with the brain.
But things are not so simple!
I'm not going to make an argument for (or against) the afterlife here. I just want to point out that if the soul is a property of the brain, then the soul still might be immortal.
After the end of the brain, another brain could have the same property!
Most religions believe either in a nonmaterial afterlife, like Heaven, or in reincarnation. If you believe in reincarnation, the idea of your self ending up in another brain is nothing new. If you believe in Heaven, then you still can believe that the soul is a property - if you are willing to believe that there are bodies of some kind in Heaven, with brains of some kind!
I'm not suggesting that any of these beliefs are true. I'm not going to take a stand for or against belief in the afterlife. My point is just this: that the property version of the soul does not rule out belief in an afterlife. It also doesn't force you to believe in an afterlife. It just leaves the question of the afterlife open, for you to decide for yourself.
So we don't live in a world of things alone. We live in a world of things and properties. Once we realize that, and take the reality of properties fully to heart, we begin to see what spirit might be. The world of spirit might not be supernatural at all. Instead, it might be a part of the world of properties - the part that contains a mysterious and complex property of each of us, the property that we call the self.
I'm including these notes to thank the sources of some of the ideas in this post, and to fill in some technical details that students of philosophy might find interesting.
The name of the question of the existence of properties and such is "the problem of universals." (Technically, the question "Do properties exist?" is only part of the problem of universals, but it's the most important part.)
My position that properties are real is a milder version of what Plato thought about properties (the so-called "Platonic realist" view). However, you don't have to believe everything Plato said to accept my view of properties! (See this paper for details.)
The idea that the soul is a property of the body, but still is an item distinct from the body, is a version of what philosophers of mind call "property dualism." (Property dualists usually don't use the idea of "soul" - often their position is that conscious experiences are nonphysical properties of the brain.) Property dualism is different from "substance dualism" - the idea that the soul or self is a kind of mental substance associated with the body. Descartes was a "dualistic interactionist" - a substance dualist who thought the soul could act on, and be acted on by, the body.
The idea that the soul could be immortal even if it is "only" a property of the brain is not new. Plato thought of the soul as something sort of like a property (an "abstract object" as philosophers would call it today). Plato thought of the soul as immortal. See this paper of mine for my take on Plato's view of the soul. The idea that the self, as an abstract object, might be potentially immortal comes up in modern thought, for example in Daniel C. Dennett's book Consciousness Explained. (I disagree with Dennett on some important points - see this paper - but this idea is interesting.)
(This post was slightly reformatted after posting.)
posted at: 01:50 | path: /mind | persistent link to this entry
Fri, 11 Jul 2008
Still No Disproof of Free Will
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