Thank you for your question. For a long while in the history of philosophy it was thought that what was conceivable was a good indication of what was possible. Descartes is a good example of this way of thinking, though he was careful to require that not any old conceiving of a thing showed it to be possible. Rather he required that the conceiving had to be "clear and distinct", meaning roughly that it had to pass the most stringent standards we can muster to make sure the conceiving is coherent (i.e., not subtly self-contradictory). In the middle of the 20th century this methodology began to break down. For instance, in the Sixties Hilary Putnam distinguished between concepts and properties, making clear that our concepts of things like gold may not reveal its true properties. Similarly, Kripke's notion a decade later of "natural kinds" made room for the possibility that what is "metaphysically possible" may not correspond to that is conceivable.

This issue is still a topic of intense debate. Some philosophers in the last decade or so have argued that conceivability considerations have *some* force in determining what is genuinely possible. For instance, see Frank Jackson's, From Metaphysics to Ethics: A Defense of Conceptual Analysis, Oxford University Press, 1997. I should mention that conceivability does seem an important tool for many fields, not just philosophy: for instance, physics uses thought experiments regularly. Those "experiments" are constrained by what we know of the laws of physics, but philosophers' thought experiments can take into account all we know also about the empirical world. Imagine, further, how hard it would be to reason in ethics or political philosophy without being about to construct thought experiments! The moral here is that conceivability considerations are not aimed at finding out about our minds, but rather are our attempts to use common sense, albeit fallibly, to find out about the world.

Mitch Green

If you just reflect on your own experience you can see that the feeling that the pain is in your hand is not merely a matter of having learned over time that certain feelings are caused by damage in certain areas; on the contrary, your hand, as we say, "hurts". Infants clearly show recognition of the locations of pains in their bodies, and yet they certainly haven't had sufficient experience to learn the requisite correlations. Also, notice that sometimes we're wrong. This happens with tooth pain a lot. We feel the pain in one tooth but it's actually caused by damage in a different tooth. How would this mistake even occur if there weren't something inherent in the feeling itself concerning which tooth hurt? One fairly simple way to account for the localization of pains is this: The relevant nerves in the damaged area send signals to the pain centers of the brain, which represent both the damage and the location of the damage. The identities of the nerves from which the message emanated, or their location, is presumably part of the information contained in the message that reaches the pain centers. So the feeling will encode both something about the nature of the damage and the location in which it occurred.

We don't have two brains, we have much more! Philosophers (like Dan Dennett) and cognitive scientists (like Dan Sperber and Steven Pinker) argue that we have sub-personal processes that go on all the time in our mind/brain without the least control by our conscious processes, as when we parse a sentence in a natural language, a process that requires a highly sophisticated human mind but of which we do not have any conscious cue. The phenomenon you mentioned is at least similar to the "slip of the tongue" phenomenon, which is well known by psychologists (Freud also wrote an essay on it). There is a lot that is going on inside our brain and that we're not able to monitorate by our conscious processes.

In some sense of course the nervous system is an extension of the brain, and precisely where one sets the boundary of the brain is somewhat arbitrary. However there is a point to distinguishing the function of the nerves in the hand that detect the damage in question - say, a cut - from the function of higher-level centers in the cortex that process the information and mediate responses (such as grabbing the hand, putting pressure on the cut, etc.). Rather than speak of "projection of the pain" by the brain, I would describe what's going on as the brain representing damage in the hand (that's the pain - it's represented as located in the hand) based upon the inputs received from the nerves in the hand. So long as the best explanation of cognitive and perceptual activity requires describing the mind/brain in terms of distinct faculties with distinct functions - and this is of course an empirical question, but I believe there is good reason to accept it - it would only undermine the explanatory project to treat all nervous tissue as just "part of the brain". The fact that the tissue is made of the same stuff doesn't automatically entail that it performs the same function.

I wasn't entirely sure how many issues were on the table here. Your first question seemed to be whether it's contradictory to say that one person has two minds. But as your question continued, the issue seemed to be whether it's possible in general for there to be more than one mind.

There's no obvious reason to think there couldn't be many separate minds, and of course what we usually assume is that there are. Whether solipsism is coherent is something that some people have doubted, but I've never found the doubts very convincing. So the question we'll tackle is whether you or I might have more than one mind or self.

Interestingly enough, there are serious reasons for saying that the answer is yes. There are two bits here. One has to do with the brain. It has two hemispheres, and in patients with severe epilepsy, sometimes the only way to relieve the symtoms is to sever the corpus callosum -- the bundle of nerves that connects the two sides. Although there is room to argue about the details, there is reason to think that in cases like this, there really are two separate centers of consciousness. The philosopher Derek Parit, among others, has considered this kind of case in some detail. And if Parfit's interpretation is correct, the most plausible thing to say is that one person can have two minds or two centers of consciousness. Here are a couple of youtube videos:

http://www.youtube.com/watch?v=MZnyQewsB_Y
http://www.youtube.com/watch?v=ZMLzP1VCANo

As you'll see, the researcher in these videos doesn't agree that both hemispheres are conscious, but other researchers think otherwise.

The second bit in Parfit's view is that the very notion of a person is actually a shallow one. If we describe the split brain case in detail, making clear how it works and what the phenomena are, then the question of whether this is "really" one person with two minds or two persons is more or less a matter of what sort of description we prefer. But what seems clear is that one brain/body might well contain two more or less independent centers of consciousness that typically manage to co-operate but that are importantly distinct from one another.

In order to answer your question, I need to explain a distinction between two kinds of mental state: propositional attitude states, and qualitative states. A propositional attitude state is, as the name suggests, a state of having an attitude toward a proposition. Take the proposition expressed by the sentence, “there is milk in the fridge.” I can believe that proposition, that is, I can believe that there is milk in the fridge, but I can take other attitudes as well – I can hope that there’s milk in the fridge, want there to be milk in the fridge, regret that there’s milk in the fridge (because its availability caused you to eat the last brownie, perhaps), suppose for the sake of argument that there’s milk in the fridge, pretend that there’s milk in the fridge, etc. The point is that all these kinds of mental state crucially involve propositions or propositional content. A qualitative state is the state of simply experiencing – it’s a state where it “feels like” something to be in that state. Qualitative states often involve sensory experience. So, as you wash down the last of the brownie with a cold glass of milk, as you feel the refreshing chill and savor the creamy taste and texture of the liquid, you are in a qualitative state. But a state of mind doesn’t have to be directly linked to a perception of something in the outside world in order to have qualitative character: memories, dreams, and imaginings are like this.

Qualitative states do not seem to involve propositions in the same way propositional attitude states do. When you are experiencing the taste and texture of cold milk, there is not necessarily any proposition to which you are related. You might think to yourself, as you’re drinking, “This cold milk tastes great.” But in order to think that, you would need to think of the object of your experience in a particular way – as milk. We say that you would need the concept, MILK, in order to think the proposition “This is mighty fine milk.” But you don’t need that concept in order to experience the taste of milk. If you had never tasted milk before, never seen milk or heard of milk, you might still have the same qualitative experience as a veteran milk drinker. And here’s another difference: If you think to yourself, “This is mighty fine milk” and it turns out that what you’re drinking is not milk, then you have thought something false. But there’s no way that your experience of the taste of milk can be false or incorrect – it is what it is. Emotions are also kinds of qualitative state. (These are the mundane truths that lies behind a lot of pop psychology.)

Now some philosophers disagree with me about the distinction between these two kinds of state. They hold that qualitative states do, in the final analysis, have a kind of propositional content, that they, like beliefs, make a kind of claim about the way the world is. So in my example, the experience of drinking cold milk does involve the belief that I am drinking cold milk. But two points: first, theses philosophers admit that it takes argument to show that qualitative states have propositional content – that there’s at least a recognizable difference between these two kinds of state, and second, that having propositional content and having correctness conditions go together. That is, if qualitative states have propositional content, then they can be applauded or criticized in just the same way and for just the same reason as beliefs are applauded or criticized, because they are either true or false. If qualitative states have propositional content, then they can be true or false, right or wrong. The mere occurrence of a state of this sort doesn’t – can’t – guarantee that its content is correct. (Qualification: unless the content is supposed to be something that concerns the occurrence or character of the state itself.) So – I’m afraid of spiders. Some philosophers think that experiencing fear of an object is (essentially) like believing that that object is dangerous. If I continue to be afraid of a spider after it’s determined that it’s harmless, then I’m being irrational, just as I would be if I believed both that it was and that it wasn’t dangerous.

Now it’s clear that people who engage seriously in meditation put themselves in qualitative states that are quite different from the states they are in when they are just going about their everyday lives (although I’m told that in at least some practices, one aim of meditative practice is to carry something of the qualitative character of the meditative state back to everyday experience). People often report finding these states enormously pleasurable, gratifying in ways that go beyond and perhaps feel substantively different from other pleasant states they’ve experienced outside meditation. Sometimes something about these states is so unusual, so compelling, and so intense that people describe them as “profound.” That much is a matter of simple observation – whatever one’s religious or spiritual beliefs, it ought to be acknowledged that certain practices can produce effects of this kind.

Now in order for me to learn anything directly from being in such a state, two things would have to be true. First, the state would have to have, in addition to having qualitative character of an extraordinary kind, propositional content. Second, the state would have to involve taking an attitude of belief toward that proposition, rather than an attitude of mere supposing or imagining. So now you have two choices: if you want to say yes, these states are states of believing propostions (like “I am in touch with all living beings”), then you should also recognize that that content might be false, and that the mere fact that you are experiencing a state with that content doesn’t justify you in believing that content. On the other hand, if you think that it doesn’t make sense to say that your experience is false or wrong or misleading, then you are denying that it’s a belief state (and maybe even that it has propositional content at all). So bottom line – the mere fact that you’ve had an extraordinarily powerful experience can’t demonstrate that any substantive claim about the world is true or false. If the experience “tells you” something, then you have to evaluate the truth or falsity of that claim the same way you would have to evaluate any other claim.

One further distinction: you might think that qualitative states lack propositional content, but still think that the occurrence of certain kinds of states indicates that certain propositions are true. You might think, for example, that the best explanation of why you can have certain kinds of profound experiences during meditation is that you are in touch with every living being. In that case, you would owe a skeptic an explanation of how it was that you thought that fact was responsible for your experience.

Couldn't agree more.

I can imagine what it would be like to feel that I was observing my body from some detached perspective. And I can certainly imagine what it would be like to have the sense that I'm aware of various things "passing through my mind" without identifying with them. But even if it somehow seemed to me that I was actually outside my mind observing it (whatever that's supposed to mean), it is a very long step from there to conclusions about what I am, or what my mind is, and how the mind or the self fits into the rest of reality.

I'd add: the experiences on offer here are interesting. But anyone who simply offers the conclusions you've described as the only reasonable way to interpret them doesn't seem to me to be doing what philosophy does. There is a large boatload of objections to the conclusion being drawn, and what someone doing philosophy would do is examine the conclusion in light of those objections.

It's also worth noting that the meditative traditions don't all come to the same conclusion about meditative experience. Ater all, one of the things that Buddhist Vipassana meditation is supposed to help us see is that there really is no such thing as the self!

So you're right to be skeptical. But it's perhaps worth saying a bit more. I have some familiarity with the practice of meditation. But what strikes me when I listen to meditation teachers talk about it -- even thoughtful, non-dogmatic teachers -- is that they often suggest metaphysical conclusions that the teachnique they're using doesn't seem capable of supporting. The relationships among mind, self and world are complicated. It's not even easy to settle on the right questions. Whatever data meditative practice may have to contribute to the enterprise (and I believe it does have a contribution to make), asking it to lay bare the deep structure of reality is asking an awful lot.

We often use the verb "to see" in such a way that to say I see a cat is to imply that there's a cat in front of me (and that my eyes are open, etc.) In this way, my beliefs about what I see could be mistaken: I can believe that I see a cat, but I could be wrong if there is no cat there for me to see.

It seems similarly odd to say that I feel pain, but there is no pain there for me to feel. The difference is that pains--unlike cats--are thought to be mind dependent. And many philosophers have thought that while we can be mistaken about the existence of things like cats, trees and tables, we cannot be mistaken about the contents of our own minds. For that reason, I can be wrong that I see a cat, but I cannot be wrong that I feel pain.

Sometimes we use the word "see" in a way that does not imply that there is an object there in front of our eyes. I could describe a dream by saying, "I saw an elephant coming toward me." Since I was dreaming, there was no elephant there for me to see. But it might still feel natural to use perceptual verbs like "see" to describe how things seem to me. According to this use of "see", we cannot be mistaken about what we see any more than we can be mistaken about whether we feel pain.

You can find this distinction between the two notions of "see" in Descartes' second Meditation. He says: "For example, I now see a light, I hear a noise, I feel heat. These things are false since I am asleep. Yet I certainly do seem to see, hear, and feel warmth. This cannot be false. Properly speaking, this is what in me is called 'sensing'. But this, precisely so taken, is nothing other than thinking." Many philosophers have followed Descartes in thinking that the latter use of "seeing" is more fundamental, though some contemporary philosophers now want to resist that idea.

It is true that many types of things are repond in systematically recognizable and conistent ways to changes in their environment: including people, other animals, other types of organisms like plants, other living things like cells, and indeed non-living things like thermometers.

Philosophers have paid some attention to ways that things like these are sensitive to their environment. To consider the final example, on one epistemological line it is right to say that thermometers represent the temperature because they are sensitive in this manner to changes in temperature. I don't think this position is tantamount to saying that thermometers think, but I'll leave it to partisans of that perspective to say more.

One idea that rings true to me comes from the great 20th Century American philosoher Wilfrid Sellars, who drew a distinction between being "senstitive" to one's environment and being "aware" of it. In particular, it seems right to me to conclude that sensitivity plants and cells and thermometers and newborn babies show to their environments, this sensitivity is very much unlike the ways that you and I think about the world, which is based on a richer form of awareness than those other things are capable of manifesting.

By itself, this distinction does not imply that thought requires language. However, Sellars develpoed this insight in that direction. Likewise, Donald Davidson--another important 20th Century American philosopher--developed interesting arguments along a similar line, and I think arguments from Stoical philosophers about the dinstinctive nature of the sort of thought that you and I can manifest are also worth taking seriously. So, it strikes me that there are rich lines of thought that suggest, first, that babies and non-human animals and plants don't think in the way that you and I do and, second, that the way we think is intricately bound up with our linguistic abilities.

You raise a number of controversial questions about the relationship of language and thought and the possession of thought by non-adult humans and non-humans. You suggest that babies and animals can think. Do you think babies at any age can think, or just babies who have reached a certain level of cognitive maturity? Do you think all animals can think, or just some? Do oysters think? It appears that you attribute thinking to any organism that can sense. But most philosophers think that there is a distinction to be made between sensation and thought. An organism may be able to feel pain, for example, when it has certain unfortunate interactions with its environment. But it doesn't follow that that such an organism is thinking about it's environment. The sensation isn't a thought or a representation of the environment, but just a feeling caused by the environmental stimulus. This is a difficult philosophical distinction, one which has exercised many a great philosopher, and there's good reason to think that many philosophers were not as aware of the distinction as they should have been. So you're in good company!

Plants are caused to be in various states in response to environmental stimuli, but it's not clear that we should even attribute sensation to them. It's difficult to say what it is to have sensations, and to demonstrate that certain things, such as rocks and plants don't have them, we certainly wouldn't want to attribute sensations to anything that is caused to change its states in response to its interactions with its environment. A rusting piece of metal has not sensed the humidity which caused it to rust. A plant's flowers may open in the sunlight, but it may not be correct to say that the plant senses the sunlight.

We haven't addressed the issue of language and thought, which seems to have motivated your other questions. Here too, we can benefit from trying to be a bit more precise. What constitutes a language? You come close to suggesting that babies and other animals have a non-verbal language. It's true that young babies and other animals communicate without words, and they do so selectively in response to their environments. But we might want to resist characterizing such vocalizations as linguistic, pending an account of what contstitutes a language.