“there has been no progress in bridging the gap between this activity in the brain and the nature of our experience, the richness of our sensations of color, sound, touch, motion, or simply awareness.”
“How, then, can the internalist theory be tested and demonstrated scientifically?”
“What about the hypothesis that Riccardo Manzotti has been setting out in these dialogues, that consciousness is actually external to the body? Are there any scientific experiments that could settle this debate?”
“Tim Parks: Riccardo, let me start with a very simple experiment, something anyone can try, that seems very much in favor of the internalists. When we look intensely at a field of red color and then shift our eyes to a white or grey surface, we see, admittedly only for a few seconds, but nevertheless very distinctly, an area of green. Since it is clear to anyone who has not been looking at red that there is no green on this white background, is it not evident that colors are generated in the brain?”
“Riccardo Manzotti: Well, first, you don’t see green but cyan, a greenish blue color.”
“Manzotti: If you had stared at green rather than red, then when you turned to the white you would see white minus green, which is magenta. And if you stared at red and then looked at a field of yellow rather than white you would see a green afterimage, which is yellow minus red.”
“Parks: Ah. What you’re saying is that what we see is dependent on what’s out there.”
“Manzotti: You are. That’s why it matters that we establish the exact color we’re seeing. Because it’s not produced in the head. It depends on what’s out there. It is what’s out there, for your altered perceptive faculties. And before we move on, let me just say that this is a classic example of how an orthodoxy—in this case the idea that experience, and in particular color, is all generated in the brain—leads to some sloppy science and even a denial of what anyone can go and check for themselves.”
“Manzotti:”
“The question of what’s “there” or what’s “now” is complex. The objects that make up our experience can be milliseconds or years away from our bodies. Photons take time to travel, neurons take time to send electrical signals. We have already suggested that although ongoing ordinary experience of the world follows a privileged neural path that makes it possible for the body to deal with phenomena immediately around it, there are also other paths, eddies as it were, where neural activity mills, or is somehow delayed, then released later in dreams, or when a surgeon stimulates a part of the brain electrically. But this does not mean the brain is creating experience.”
“Parks: I’m not entirely convinced by this. You can’t prove, scientifically, this idea of experience being buffered or delayed in neural eddies.”
“Manzotti: At this stage, no. Neuroscientists can’t disprove it, or prove that the experience is “generated” in the head. But let’s remember, we do science by forming a hypothesis, making predictions in line with that hypothesis, and inventing experiments that prove or disprove the hypothesis.”
“Manzotti: Hypothesis: All our experience is made of physical things that have had some causal relationship with our bodies. In fact, if it could be demonstrated that someone has had an experience made up of elements that were never causally related to his or her body, my theory would collapse”
“Parks: I can see we’re not going to get very far with this. Your general prediction is that every experience will be traceable back to an actual physical property in the world. But when it comes to fleeting feelings and intuitions, any such tracing back becomes extremely complicated. And I want to be brutally definite. Can you invent a clear and concrete experiment and predict an outcome of that experiment that would prove your position? Accepting of course, that if the outcome is different, you are wrong.”
“Manzotti: At present we are stuck in a dead end where the orthodoxy, internalism, is entirely dominant, but no progress is being made as to the nature of consciousness for the simple reason that, as we showed in our earlier dialogues, this orthodoxy makes no sense at all. Rather than doing any real science, we are hearing fantasies about downloading consciousness into computers and the like. Perhaps in our next conversation we could consider this state of affairs and challenge internalists to disprove the hypothesis I have put forward.”