The trouble with this idea is that, thanks to modern physics, we already know what makes things transparent. Depending on the grain pattern of a substance, light may or may not be absorbed. That's what transparency is - something going through another thing without much friction.

So your theory becomes irrelevant because in this case, empirical evidence trumps a priori speculation.

The trouble with this idea is that, thanks to modern physics, we already know what makes things transparent. Depending on the grain pattern of a substance, light may or may not be absorbed. That's what transparency is - something going through another thing without much friction.

So your theory becomes irrelevant because in this case, empirical evidence trumps a priori speculation. — darthbarracuda

So, light waves travel through transparent things.

What's this got to do with whether clear things are 'see-through' or not? Spell it out.

Why do you think this? Are you unfamiliar with any of the physics facts of life that darthbarracuda pointed out?

Here is an explanation you might find useful and which you might also find (and I found) to be a bit too much information.

What the science blogger says is this: A light wave passing through glass is absorbed and re-emitted as it passes through the substance.

That it passes through on a straight line is the effect of destructive interference on the waves to the left and right of the center point. The center point is preserved by constructive interference.

Some materials (plastic overlays for windows) are designed to scatter the light. Ordinary clear glass does not scatter the waves, so it appears to be clear.

When a wave of light is interrupted by an opaque object -- like your shoe, for instance -- the light is absorbed and NOT re-emitted.

Because that's what it means to be see-through: photons are able to pass through the material.

all the light striking objects outside your window is reflected and then propagated through the your window with more or less fidelity.

Never mind whether its a particle or a wave. The light from the sun that bounced off the billions of points on the body of the naked woman sitting on (and denting) your car roof encounters silicon atoms in your window which absorb and re-emit the light in a 'forward' direction. What you are seeing is a stream of light from the sun, bouncing off objects, and (some of it) continuing on to be absorbed at last by the cones and rods in your retina, blah blah blah.

dukkha do you understand what I wrote?

Earth to dukkha? Come in dukkha. Dukkha, are you receiving? Dukkha?

dukkha isn't responding. Mission control, fire the mission abort bomb. He must be dead or unresponsive. Might as well blow up the capsule. I want to go to the bar now.

Why do you think this? Are you unfamiliar with any of the physics facts of life that darthbarracuda pointed out? — Bitter Crank

No. You need to spell out what a physical description of light and transparency has to do with whether we can see through clear objects or not.

The argument here seems to be, light waves travel through clear objects and are refracted, therefore we directly perceive what's on the other side of glass.

What does a physical description of light have to do with the phenomenology of clear things? Spell it out.

What you are seeing is a stream of light from the sun, bouncing off objects, and (some of it) continuing on to be absorbed at last by the cones and rods in your retina, blah blah blah. — Bitter Crank

Can you elaborate on this "blah blah blah"?

↪dukkha Because that's what it means to be see-through: photons are able to pass through the material. — darthbarracuda

That's what it means for a physical object to be transparent. But I'm not talking about that, I'm talking about whether we perceive directly what's on the other side of clear things (that is, whether clear things are 'see-through') or not.

So we see a pane of glass. A physicist might come along and say that the pane is physically transparent - light waves can travel through the object. You two seem to be making this giant leap from what the physicist is saying to concluding that we directly visually perceive what is on the other side of glass.

What does transparency and light waves have to do with the phenomenology of clear things? Can you spell it out?

I seem to remember similar theories a long time ago on PF.

Anyway, light is passing through two different medium, through transparent air, then transparent water, the only difference is the arbitrary distinction between gas and liquid. I suppose you could try to compare looking at something while in a vacuum, but it might not be a comfortable experience.

A good way to test that theory would be to drop some colored liquid in the water. If the straw changes color, too, then you are looking through the liquid. If it is merely projecting onto the surface, the straw ought to be unaffected by the change in water color. Of course, water has a color, but you need enough of it to start affecting the light, so go to a deep swimming pool, stream or clear ocean. The water tends to appear blue, and things at the bottom of deep water turn blue, proving the light is filtered by the water between the object and the surface.

You need to realize that when we perceive anything, it's really just the reflection of photons traveling through a transparent gas or space.

↪dukkha You need to realize that when we perceive anything, it's really just the reflection of photons traveling through a transparent gas or space. — darthbarracuda

This theory is wrong. But regardless it entails representationalism (i.e. photons travel through eye to retina, rods and cones convert photons to neuronal impulses, neuronal impulses travel through optic cord into the brain, into the visual cortex, visual cortex generates a visual perception), and therefore the argument still stands. We're discussing the phenomenology of clear things in the world around us. Your recourse to "physical objects are transparent" doesn't matter, because per your perceptual theory we don't perceive physical objects anyway.

My way of understanding this illusion is that 'see-through' things (eg, water, glasses, glass, plastic, quartz, etc) are not actually see-through. Rather they display what's behind them on their surfaces, — dukkha

Yeah, which is called "see-through" or "transparent." Apparently you came to the conclusion that "see-through" or "transparent" implied "literally invisible," but why you would have come to that conclusion is rather the mystery.

we make the mistake of thinking we're seeing the actual thing beyond/behind the surface — dukkha

But you are seeing the actual thing behind the surface. That's what "display what's behind their surfaces" refers to.

And reading further in this thread, it seems dukkha is really wanting to talk about perception, and specifically to critique naive/direct realism.

I've run into a number of folks recently (unless it's one guy posting under a bunch of different names) who seem to believe that naive/direct realism is more or less claiming that an object being perceived, if it's not literally in one's mind, somehow, is in direct contact with one's mind and/or sensory apparatuses--as if naive realists were saying that when you observe the moon, the moon is literally touching your eye.

Clearly, it would be incredibly stupid to claim such a thing. And usually, when it would be clearly, incredibly stupid to claim something, you can assume that that's not what the person is actually claiming. And indeed, that's not at all what naive realists are saying. (I'm a naive realist on perception by the way.)

On the other hand, it's clearly, incredibly stupid to believe that naive realists are saying that when they perceive the moon, the moon is literally in contact with their eyes (or minds), as if they would surely wind up with moon dirt in their eyes. So I have to assume that folks like dukkha do not believe that naive realists believe this. That's why I say, "who seem to believe" above. What they actually believe that naive realists are saying I can't quite discern yet.

Yeah, which is called "see-through" or "transparent." Apparently you came to the conclusion that "see-through" or "transparent" implied "literally invisible," but why you would have come to that conclusion is rather the mystery. — Terrapin Station

So then you agree with me that clear things aren't see through?

But you are seeing the actual thing behind the surface. — Terrapin Station

Suppose not.

Yawn. Looks like once again Terrapin Station, you've made another argument which doesn't make any sense. And your inane condescending strawman above isn't even worth responding to.

Don't bother replying.

So then you agree with me that clear things aren't see through? — dukkha

You don't agree with you that clear things aren't see-through.

There's an obvious misunderstanding of terms going on here. Seeing is a process that only occurs between light, eyes and a brain.

These objects are see-through because light passes through them (they are transparent) and into our eyes. Our brains use the light coming through our eyes to create a model of the world. This model is made up of visual symbols - of colors and shapes. When we say that they are "see-through" we are saying something about the relationship between the object, light, eyes and a brain. If there was just one part missing (no light, or no eyes, or no brains, or no object) then there would be no such thing as "see-through", or the visual experience of seeing through the air or a window. If there was only objects and light, then there would still be transparency, but no eyes-and-brain system to perceive this, or to complete the process, of being "see-through".

It's similar to colors. Objects aren't colorful. Colors are visual symbols that represent some quality or state of the object (like the yellow of a banana indicates it's ripeness and the black indicates it's rottenness). Colors only occur as a result of light, objects, eyes and brains interacting. Take out either of these things and colors don't occur.

So to say that things that we see through aren't actually see-through, is being contradictory.

you've made another argument which doesn't make any sense. — dukkha

He hasn't. You have. Please explain the physics by which the image appears on your hypothetical screen. What is its source, how do you see it? Is it actually there or does your brain project it onto this surface? What happens if there are say two sheets of glass between you and the object, or more? What are you seeing then?

Perhaps when you've done making stuff up to cover the cracks you could take a look at this video ...

http://sciencelearn.org.nz/Contexts/Light-and-Sight/Sci-Media/Video/Refraction

... and tell us what's wrong with this simple explanation robust enough to have survived unquestioned for over 400 years.

What the science blogger says is this: A light wave passing through glass is absorbed and re-emitted as it passes through the substance. — Bitter Crank

This seems to support dukka's position. In the stick in water example, what we are seeing is the light being emitted from the water, not from the stick itself. We see the water, not the stick, and the water is not properly "see-through".

That seems like simply shifting the ridiculous straw man a bit, though. Rather than the stick literally being in contact with one's eye, one is talking about whether a specific wave/photon was both in contact with the stick and one's eye.

I'm talking about dukka's claim, that what we see is the water, not the stick inside the water. If the light after it leaves the stick within the water, is absorbed by the water, and re-emitted by the water, to be absorbed into the eye, then we see the water, not the stick. The problem then is that the same thing must happen with the air as well, the light is absorbed into the air, and re-emitted into the eye, so we really see the air, not the water. And the air literally is in contact with one's eyes.

Yeah, I'm talking about that, too, but the process that you're describing is what it is to see the stick in the water.

No one is arguing that the stick literally touches your eye or that the same lightwaves/photons that touched the stick also touch your eyes. (Even though the latter isn't precluded.) That's not what anyone is saying by "seeing the stick in the water."

No one is arguing that the stick literally touches your eye or that the same lightwaves/photons that touched the stick also touch your eyes. (Even though the latter isn't precluded.) That's not what anyone is saying by "seeing the stick in the water." — Terrapin Station

According to what Bittercrank wrote though, it is not the same "lightwaves/photons" that touch the stick as which touch your eyes. The ones that leave the stick get absorbed into the water. Then the water releases new ones. If this is true, then this supports dukka's claim that what we are seeing is the water, not the stick. But the photons must also get absorbed into the air, and new ones released into your eyes, so really, you don't even see the water, you see the air.

According to what Bittercrank wrote though, it is not the same "lightwaves/photons" that touch the stick as which touch your eyes. — Metaphysician Undercover

Right, and according to my post that you're responding to, "No one is arguing that the stick literally touches your eye or that the same lightwaves/photons that touched the stick also touch your eyes."

No one means that by "seeing the stick."

So arguing against that isn't arguing against seeing the stick. It's arguing against a straw man.

Right. A specific photon doesn't travel from a light source to your eyeball directly, unless you and the light source are in the same vacuum with no barriers in between. In an atmosphere, or in a room with windows, or when looking at the stick in the swamp water, photons are absorbed atoms of silicon or H2O or N, O, and CO2, etc. and re-emitted, one after another, until they reach your retina and are finally absorbed by your tissue.

I'm pretty ignorant when it comes to physics. My guess is that photons passing through the air encounter far fewer atoms than they do in water or glass.

When you look at a stick in the water, you are seeing the stick, the water, and anything else that is dense enough, reflective enough, and non-transparent enough to change the light that reaches your retina. I can't see the air in this room because there are not enough atoms to refract light enough to see refraction. When I look out the window, the sky is blue because between me and the upper atmosphere there IS enough gas to refract light waves.

There is no such thing as a perfectly opaque substance because, if nothing else, quanta will always teleport right through anything. My own view is this reflects the fact that metaphysical extremes are always forbidden. For example, you might ask if a black hole is transparent and the answer is yes. Whatever goes in comes back out again in the form of virtual particles because the black hole's event horizon is where its normalized contents exchange identities with the greater context preventing metaphysical extremes such as someone creating a rock so heavy even God can't lift it. This supports the principle of Baryon conservation in quantum mechanics which insists that information is never destroyed or lost.

Even in a sealed vacuum chamber virtual particles will appear out of nowhere and the human eye is sensitive enough to detect a single photon. Meaning that, metaphorically speaking, things are transparent to ensure that nobody is ever left completely in the dark.

The ones that leave the stick get absorbed into the water. Then the water releases new ones. — Metaphysician Undercover

No. No. No. That's ignoring the wave/particle duality of photons to say nothing of the constant speed of light. When one hits a molecule it is absorbed and re-emitted. What goes in comes out the other side intact. So the photons that leave the stick are the exact same ones that hit our retinas and we do see the stick. Not the water, not the air, not some hypothetical or virtual screen, the stick!

Photons have no known independent identity of their own conveying energy and information with perfect fidelity, being instantly emitted and absorbed, and experiencing isomorphic space-time. In other words, their behavior is the same as that of their own shadows which don't recognize space or time or display any identifiable contents. The implication being that photons are made out of empty space and the Unruh Effect suggests at relativistic speeds space itself becomes a wall of radiation. It should be tested within perhaps three years at accelerators.

When I look out the window, the sky is blue because between me and the upper atmosphere there IS enough gas to refract light waves. — Bitter Crank

So, refracted light waves reach your retina. The retinal rods and cones convert the refracted light wave into a neuronal impulses. The impulses travel down the optic nerve, through the brain and into the visual cortex. The visual cortex generates a visual experience. This is a type of representationalism. *

It appears nobody can discuss phenomenology without bickering over physical descriptions of light and visual perception. So my strategy now is to show that the scientific view of perception entails representationalism, and therefore we can get back to discussing the OP because it isn't physical things that the representationalism is seeing around him. The world around him is a conscious experience generated by a physical brain, which represents the physical world (which contains refracted light waves) existing beyond the physical brain.

*http://m.pnas.org/content/98/22/12340.full

To spell it out; seeing as though the objects around us are not the physical objects that (we hypothesise to) exist in the external physical world, but rather are our physical brains *interpretation* of the physical world - an internal model, an internal visual representation of the physical world existing beyond it. Because it's not the actual physical object beyond the brain which we are directly looking at (as if our eyes are windows upon the world which we look 'through', but rather an internal visual perception - a representation of those (hypothesised) physical objects, then within the context of this thread we OUGHT have no problems with discussing the phenomenology of the physical brains internally generated visual perception. And the thing we are therefore discussing is whether the brain interprets glass much like it interprets the light coming from a television screen, whereby you are looking at a flat screen, but you also experience an illusion of depth beyond the screen. So to spell it out, if this is the same as how we see glass, when we look at glass we are looking at a flat surface but are experiencing an illusion of depth beyond the glass. Or when we look at glass are the things we see not an illusion od depth, but actual depth as in it is the objects beyond the pane of glass which are being internally represented by the brain.

We can put it like this, does the brain interpret light coming from a pane of glass as coming from a flat surface, much like a television screen (i.e. the brain does not present the TV as if the things on the screen are actually behind the television and we are looking *through* the screen at those objects as if the television is a 3d diorama). Or does the brain interpret light coming from glass in much the same way as it does interpret light coming from objects like chairs cups etc, whereby the depth you perceive is not an illusion on a flat surface.

Is the depth perception we perceive in a pane of glass an illusion on the surface of the glass which makes it look like we are seeing the objects/world beyond the pane of glass, or does the brain interpret light coming from a pane of glass as if the glass is invisible and the light is coming from the various objects beyond the pane which exist at varying depths?

I say that when we look at glass it is much like looking at an ultra high def television screen (no matter how close you go you can't see the pixels!) whereby we are looking at the surface of a flat object (pane of glass) but are experiencing an illusion of depth much like when we see the flat screen of a television but the image displayed appears to have some depth (i.e. some objects appear closer than others, it's not experienced as a 2D flat image it appears to have depth). Of course there is a difference between seeing an illusion of depth in a television screen and seeing one on a pane of glass, and that's that people don't 'believe' the TV screen illusion of depth - people don't think they're actually looking at things which exist behind the television screen - they recognise that it's an illusion and they're just seeing an illusion of depth on a flat screen, whereas MOST people (not me) do not recognise the illusion of depth on the surface of glass (because it's almost entirely seamless) and actually think that, much like someone seeing somebody on a TV screen and thinking that person is behind the television in their house, the depth perceived in glass is not an illusion and it is the objects beyond the pane that one is perceiving.

Basically you're all falling for an illusion and I'm not ;)

I would also like to point out, as an aside, that people ought have no problem discussing the phenomenology of their visual experiences without getting caught up and bogged down by physical descriptions of light and of the physical explanation/description of how perception is generated. I think the only reason this has happened is you all subscribe to the physical description of visual perception while at the same time not grasping that it entails representionalism because you want it both ways - a physical account of perception, and the objects around you being the actual physical objects in the external world which you are directly seeing, much like the naive realist.

Phenomenology has no ontological commitments, so there really should be no issue discussing it without bringing in the theory of physicalism.

are the exact same ones that hit our retinas and we do see the stick. — Barry Etheridge

This is highly confused. Light from a physical object hits your retina, gets converted to a neuronal impulse which travels to the visual cortex... and then we see the physical stick in the external world directly. How? Light hits the retina and a neuronal impulse travels through the brain, some magic happens and then we look *through* our retinas like they're windows upon the world? This is utterly confused.

So to spell it out, if this is the same as how we see glass, when we look at glass we are looking at a flat surface but are experiencing an illusion of depth beyond the glass. Or when we look at glass are the things we see not an illusion od depth, but actual depth as in it is the objects beyond the pane of glass which are being internally represented by the brain. — dukkha

I think that in a TV screen there is a source of light radiation, right there in the screen, but in the case of glass, the source of light is further beyond the glass itself. So these two are quite different with respect to the "illusion of depth".

Because it's not the actual physical object beyond the brain which we are directly looking at (as if our eyes are windows upon the world which we look 'through', but rather an internal visual perception - a representation of those (hypothesised) physical objects, then within the context of this thread we OUGHT have no problems with discussing the phenomenology of the physical brains internally generated visual perception. — dukkha

If your claim is that the entire visual perception is created by the brain, without any influence from things external to the brain, then what's the point in discussing how the brain differentiates between one object and another, in any sense whatsoever? If all the objects are simply created by the brain, then there is no difference between the TV screen and the glass, because they are both simply creations of the brain. Nor is there any real difference between any object created by the brain, in the sense that these are all fictions. However, the brain might create such a difference, dictate that X is different than Y. But then any difference is just a difference because the brain determines it as a difference.