professor frink said:
You said that the image exists nowhere in the physical world. I explained that if there is an image, it exists between the ball and the eye as photons. I can't comment on the nature of hallucinations, because I am not a neurophysiologist.
Well, if the situation with the photons (seeing an actual ball) and without them (hallucinating) have the exact same sensory experience and generate the same exact image (there is no difference in the mind between a hallucination and the real thing), then it is pretty clear that the image does not take place in the physical world at all, but only in the mind.
No. The photons are indeed the image. If those photons hit a light sensative film, there will be a chemical reaction. This can eventually be developed into a photograph, but that is not necessary. I could take that film, analyse it chemically and deduce what the image likely was, without ever actually seeing the image. Granted this would be very hard, but given enough time and patience, I could do it.
No, you couldn't. You could infer that the person was seeing a red ball, but the image itself you have no access to.
Think of bats: you can analyze their brains and the sound waves they receive and come to the conclusion the bat is sensing, through eco-location, a pillar ahead of him. However, you have no idea of the bat's experience of this pillar (it uses a sense we don't even possess). The same is true with the vision of others. You know what they are seeing, but you have no access to their vision.
They still see the ball though. They just interpret red differently that you or I. Nonetheless, as I stated, I am no neuroscientist, so I cannot address what goes on in the brain.
Indeed, and I have made it pretty clear all along that I'm talking about the image of the ball, and not of the ball.
It's the same ball for two people, but one sees it red, the other sees it grey. The photons and neurons are all the same, yet the experience is different. And it is this experience (the image of the ball), that I'm talking about. Not the physical elements which cause it to happen (photons).
There is a certain kind of photon that is called red, and everyone agrees that they produce an experience of something everyone calls red. But this red may be experienced differently by everyone. And this experience (the images, the smells, the sounds; NOT the photons, molecules and vibrations) does not exist in the physical world.
Basically, I think we both agree, but while I was using the subjective definition of image (what each person actually sees, experiences) you were referring to the physical definition.