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Am I correct in thinking that vibrations in the air are just one cause of sound,

Am I correct in thinking that vibrations in the air are just one cause of sound, and that really sounds are what are experienced? So for example under this definition of sound, ringing in the ears is included. Equally then, that sights can be caused by light bouncing off objects but also by the imagination? Can I draw the conclusion then that there are an equal number of sounds/sights/tastes/smells/feelings that have ever existed, than have ever been seen/heard/tasted/smelled/felt? The tree that falls in the woods with no one in it makes no sound at all (but plenty of vibrations)?

The issue here seems to be verbal. It's not clear that ordinary language has a settled answer to the question whether "sound" refers to the vibration in the air, or to the experience that the vibrations cause. If we fix on the former, then there have been plenty of sounds that never led to any experiences. If we fix on the latter, then sounds and experiences of a certain sort are one and the same thing. But there's no deep fact about which is the "right" way to think of it.

Something else worth keeping in mind: language doesn't map onto the world in any simple, direct way, and in particular we need to be careful about letting the fact that we have the noun "sound" fool us into thinking that there is some thing in the world -- a sound -- whose location (in the head? in the landscape?...) needs to be sorted out.

Are rainbows real? That is, do they exist unperceived?

Are rainbows real? That is, do they exist unperceived?

The Guinness Book of Records says (or at any rate, used to say) that the world’s longest lasting rainbow was continuously visible over Sheffield for some six hours on 14 March 1994. Here's a picture (I had an office in the Arts Tower at the time which is why I know about it!)

Now, did the Book of Records do some research to check that at every single second from 9am to 3pm, someone or other was perceiving the rainbow? I very much doubt it! I guess that the Book of Records supposed that, to establish the record, it was enough to have grounds for thinking that,at any moment in those six hours, someone suitably placed and lookingin the right direction would have seen the rainbow (it was continuously perceivable, though not necessarily continuously perceived).

And the Book of Records is speaking here entirely in accordance with our ordinary ways of talking about rainbows as continuing to exist unperceived. I see a dramatic double rainbow, go to fetch someone to see it, and when we get back to the window say "oh good, it is still there". And what makes it the same rainbow that is still there at those two different times? Indeed, what makes it the same rainbow that is visible at a given time by differently located people, given that it would look to be in a very slightly different location to them? Nice questions! Presumbably the answers will appeal to something to do with the continuity of what would have been seen over time had we been looking, or the continuity of what would be seen if we moved from one viewing position to another.

Anyway, we certainly do talk of seeing the same rainbow again after a temporal gap, when perhaps no one happens to be looking. We do talk as if rainbows can continue to exist unperceived.

But ok, should we talk that way? Given what we know about the mechanisms by which we come to see rainbows as we do, should we really talk about them sometimes as if they are real persisting things than can exist unperceived?

Well, why not? I'm inclined to be pretty relaxed about this. Talk as you like -- so long as you are not misled!

Rainbows are variously like rabbits, rivers, ripples, holograms, and mirror images, in each case in some ways and not in other ways. In different contexts, we might want to stress different similarities or dissimilarities among such things. Perhaps a small child will be helped a bit to understand what is going on if you say "Rainbows aren't really there you know, there isn't a real coloured arch in the sky". But equally, if the same small child starts to think of rainbows as a kind of waking dream or a private illusion, then we might say "Oh it is really there, I can see it too!".

Which suggests that here (as elsewhere) the dichotomy "real"/"not real" is a crude tool -- and what we (seem to) talk about doesn't in fact sharply divide into two neat categories.

But still, the similarities between rainbows and central cases of "real" things are probably enough to give point to those everyday, Book of Records, ways of treating rainbows as real things that can exist unperceived. So we might as well, to that extent, continue to fall in with our ordinary language practice here.

So long as we do not mislead ourselves ...

I have a theory which I would like to develop. I was wondering if it is possible

I have a theory which I would like to develop. I was wondering if it is possible that all human perception could differ from person to person. My reasoning is, if you are born into this world a seeing, hearing, smelling, feeling, tasting individual, your senses learn to describe different perceptible things form that very time. The problem with this is, is that each individual has parents, who also had parents, who had parents and so on. If I was born, and I saw a completely different world, or tasted things very differently, I wouldn't be able to communicate these things because every description I can provide is synonymous to what it is called. For example. If I am looking at what is called an apple, I see a round, object with a stem. For the sake of argument it will be a red apple. The thing is, I could be seeing a spinning vortex, but because this is how I have always perceived things, I describe it at a red apple. I suppose this isn't a question, but what do you think?

Your view about the possibility that people perceive things radically differently is an old philosophical puzzle. The so-called "inverted spectrum" hypothesis is the most common variant. Assuming that color space is organized symmetrically, so that one can switch primary colors like red and green, or blue and yellow, while maintaining all the similarity relations among them, it seems someone could see red wherever others see green and yet there be no difference in their behavior. As you point out, they would learn to call red things "red", even though they looked green to them. Perhaps there could be inversions of other properties as well. So is this really possible?

One way of approaching the issue is to distinguish between what we might call the "representational content" of a perceptual experience and its "qualitative character". The representational content is what the perceptual experience is "saying" about the world around you. So if you see a red apple, your visual experience is "telling you" that there is a red, round object, an apple, at a certain location. The qualitative character is the subjective "feel" of the experience, what it's like for you to be seeing the apple. Given this distinction, we can ask whether the possibility of a behaviorally undetectable inversion - a difference in experiences that can't be detected by what the people say or how they act - applies to both the representational content and to the qualitative character, or just one (or, indeed, neither).

There are good reasons for thinking that an inversion with respect to what the experience is representing is not possible. The point is that on a very plausible theory of what determines what the experience is representing, a theory that grounds the representational content in the facts about what conditions in the world reliably produce the experience, the sort of inversion you are imagining won't occur. Since both people are experiencing what is reliably produced by the same wordly conditions, their experiences will automatically count as representing the same conditions. However, when it comes to the more elusive feature of qualitative character, it does seem possible that an inversion occur. Some philosophers try to argue that such inversions aren't possible, but I, for one, have never been convinced by their arguments.

Living things have perception. When a sensory cell is disturbed, a chain

Living things have perception. When a sensory cell is disturbed, a chain reaction is caused which sends the sensory data to the brain where, through very physical means, it is analyzed and thoughts and emotions are created. If this is all done by physical means, by the complex physical reaction which is the nervous system, do seemingly non-organic things such as my computer have perceptions as I do?

If your question is whether “yourcomputer,” which I take to be an ordinary personal computer, has perceptions asyou do, then the answer is clearly “no.” Your computer has input devices suchas a keyboard, and possibly a scanner, a video camera, and a microphone. Such input devices transduceranalog physical processes into discrete digital symbols, and those symbols arestored in various locations in the computer and then can be manipulated inconcert with computer programs and further input. Your brain also takes inputfrom external physical stimuli such as light, sound waves, etc. It alsotransduces those signals into other forms, typically chemical and thenelectrical signals. Those electrical signals – action potentials, are then propagatedto other locations in the central nervous system. So both the brain and yourcomputer transducer signals and do things with them. One could call bothprocesses “perception”, though the actual mechanisms in your pc and your brain arefunctionally different, and it is a bit misleading to describe them both asperceptual mechanisms.

A related question is whether computerscould have perceptions, that is,whether we could build computers which transduce external stimuli in the sameway our brains do. This question is harder to answer, and it’s one widelydebated in the philosophy of mind and cognitive science. Part of the reasonthis is such a difficult question to answer is hinted at in your question. Ourperceptual systems begin with external physical stimuli, but we wind up with “thoughtsand emotions.” So to build a computerwhich takes in such stimuli and stores or outputs thoughts and emotions wouldrequire that we not only have a functional account of the mechanisms by whichwe receive such stimuli and begin to transduce and store it, but a full accountof what the mind/brain does with such information in order to bring about therich experiential life we enjoy.

How can anybody, including myself, be sure that what is seen is real?

How can anybody, including myself, be sure that what is seen is real? My right eye was scratched, and I can see this scratch-mark before "reality", as one would see their right hand before their left if they arranged the two that way. I wonder if this proves the external to be an actual place within something (the universe?), like it has an absolute position within my (a sentient being) perception. This brings me to my final question: How can I prove the distance between my two hands? When I look at my right hand in front of my left hand, I see them as two objects apart from each other, but I sometimes see a flat picture, like a movie screen: it is manifestly flat but produces 3-dimensional pictures. Does this mean that my eyes create reality to be other than what it is, like how they create depth to be where it really is not? Or does this mean that my eyes are perceiving reality as it should be perceived? Ugh! And the thought that those who cannot "see things" in ink-blots on white paper have learning...

Yeah, these are the kinds of questions that lead many of us to "Argggh!" They're also the kind of questions that I approach with a great deal of trepidation because they are knottier than knotty. So, please understand that what I say here by the nature of this kind of exposition will be very rough and overly simplistic. You'll also probably find more than a few of my colleauges to disagree. But anyway, let's barrel right on with it.

I don't think you can be absolutely sure that what you see is what's "real"--though you really ought to take some time to parse out what you mean by that word because it's LOADED. I take it that you mean by "real" something like what's out there independently of us. In a sense, actually, my best shot is that what you or we see isn't exactly real in that sense. Do remember that old Aristotelian question, "When a tree falls in the forest and there's no one around to listen, does it make a sound?" Well . . . get ready . . . almost yes, but no. No in the way that it's not precisely right even to talk about "trees" and "forests" existing independently of us. Before you call for an ambulance to pick me up, what I mean by that crazy sentence is that what we experience is a kind of product of a number of factors, roughly our perceptual faculties and what seems to exist independently of us and interacts with them. The sound of a tree falling, for example, is the product of (1) our sense of hearing and (2) something like sound waves. Without either of these factors there's no sound. (If you think about it, this is actually obvious. Just ask any deaf person, or go into a silent room.) We contribute some of what goes into experience, and the external stuff contributes some of it. That goes for all the other dimensions of our experience of a tree falling or just a tree. Since in this sense there is no "sound" without the hearing of sound, then it really isn't meaningful to ask whether the sound we hear is the same as the sound that's out there. You see, there is no sound out there. Sound, like every other perceptual experience, exists in the relationship the relationship between us and what's not us. (Actually, I shouldn't even say "us"; but let's just let that slide.) No objects of experience strictly speaking exist out there. Now, it doesn't follow from this that nothing exists beyond us. I think there are pretty convincing, if not absolutely convincing, reasons to think so--at least I'm convinced. The shorthand way I'd put it is that the world we experience is external reality as it appears to us through its interactions with us. (And we are what we experience of us in the course of that interaction--there, I've said it.)

About your eye, I'd say you interpret what you see as a scratch, and your interpretation works better than others. So, go with it.

About whether we experience reality the way it "should" be experienced. I don't think there's any way reality "should be perceived". It just is perceived, and we make the best of it we can.

About "proving" the distance between your hands, I'm not sure what you mean. Once you've accepted hands and distance as meaningful, once you're in that relationship, you pick up (or have someone else pick up) a measuring tape and measure.

About seeing three dimensinal pictures at the movies, I'd say you see two-dimensional pictures that you full well know are two-dimensional and interpret them or imagine them as representations of three-dimensional things. You don't really think of them as three-dimensional; otherwise you'd duck when someone shot towards the screen or a robot exploded, or something.

Do we "see" black objects in the same sense that we see objects of other colors?

Do we "see" black objects in the same sense that we see objects of other colors? Black objects being those which reflect no light, how is looking at a black object different than closing your eyes (it seems absurd to say that we see anything with our eyes closed); in either case, no light reflects from the object to our eyes. If I have a white piece of paper with a black spot on it, do I "see" the spot, or do I infer it?

This question reminds me of an experience I had going to rent a tuxedo. I told the clerk I wanted a black tuxedo, and he responded with the question, "What shade of black?"

I suppose the answer here depends upon what you mean by "see" and by "black." I'm inclined to think that all "seeing" of objects involves a kind of inference or judgment. That is one judges what one sees to be an object. Does it really matter whether the physical cause of what one sees and hence the basis of judgment is light or the absence of light? I'm not sure I see why.

What my haberdasher taught me, however, should also be said. That when we see some "black" object, we really don't see utter colorlessness. We see all kinds of shades of gray, etc., so much so that one might argue that we never really see a purely black object (unless one is staring a black hole, I suppose, which perhaps isn't really an object, anyway). We also see boundaries with other hues, as well as shadows and patterns of motion and interaction with other objects--all of which inform our judgment that a black object is before us.

We know that after images are formed as a result of latency in the retinas of

We know that after images are formed as a result of latency in the retinas of our eyes. So if they are in our eyes or, more likely, in our brains, why do we see them in front of our eyes? How do they get out there?

The good news is that this feature of after-images seems no more difficult to explain than how we see physical object like a table 'out there'. True, there is an actual table out there while there is nothing corresponding to the after image out there, but this makes no difference. In both cases, something inside our head is managing to present something as out there. (Fortunately, the table doesn't come into our heads when we see it.)

So I think your question is just how the brain or the mind manages to see things as outside itself, whether there really are those things out there or not. The bad news is that we really seem to have no idea how this is possible (which is not to say that philosophers -- including notably Immanuel Kant -- haven't spent a lot of time worrying about it).

Are all of the senses (taste, sight, etc.) equally credible?

Are all of the senses (taste, sight, etc.) equally credible?

This is an excellent question, but one of the reasons it is not easy to answer is that we are not comparing like with like, because different senses give us information about different kinds of thing. It’s not like two people who tell you about astronomy where we might say that one person is more credible than the other on the same subject.

Take sight and taste. Sight seems to give more information about the external world, but in part for that very reason it is more open to error. Taste seems to give much more restricted and subjective information, and in part for that very reason it is less open to error. Having said that, however, all the senses may form the basis for inferences about what is going on in the external world, and any of these inferences may go wrong.

Another reason your question is hard is that philosophers don’t agree about what counts as the senses getting things right. Take the colors that we believe things to have on the basis of sight. Some philosophers think that our eyes do a pretty good job here; others think that this is a case where they get it wrong every time, since external objects never have colors in the way we see them. According to the anti-color lobby, what is going on in color vision is that we take our inner color experiences (which are real but entirely mental) and mistakenly project them out onto external objects.

Appearances can be deceiving. I feel that humans are hindered by what they

Appearances can be deceiving. I feel that humans are hindered by what they perceive, visually. Perhaps almost all forms of major prejudice come from visual representation of ideas that we believe we do not like. I feel that sight is an anchor to the physical realm and without it, perhaps humans could transcend into higher states of being, perhaps becoming super-human, evolutionarily speaking. So my question is: Philosophically, do you feel that humans are hindered from becoming a complete being due to some of our inherent senses, etc. and do you feel it is possible to overcome these physical limitations to attain a higher state of being?

I agree that sight and indeed the senses are our anchor to the physical realm, but I think that is a good thing, since the physical realm is what we need to understand. At the same time, our senses give us only very limited contact with the physical world, much of which is unobservable. Creatures with different senses might have a cognitive advantage over us in this respect. But any sort of physical sense we can imagine (such as echolocation in bats, or exotic sensory sensitivity to chemicals) would still require massive inference from the limited effects of the world the experiencer to the complex worldly causes of those effects. At the same time, science has done an impressive job of reducing the limitations stemming from the peculiarities of the human sensory endowment through the construction of instruments that enable us to detect things we cannot directly observe.

In today's society, there are certain conceptual frameworks which change the way

In today's society, there are certain conceptual frameworks which change the way people perceive others in their everyday life. For example, history, since the times of slavery in America, has dictated that blacks are "irrational", or "incompetent", and that they are subordinate. This is obviously not true, if you perceive people in an intrinsic manner. There are many frameworks for other groups, such as women, homosexuals, etc. My question is, how are we to rid ourselves of this framework? Is there any way to do so, or are they too ingrained into our society?

I don't think it is humanly possible not to have any prejudices at all. So I don't think that ridding ourselves of this "framework" is a realistic goal. What we can and should do is to continue to subject our assumptions to free questioning and challenge. That's one of many good reasons why society needs philosophers!