This is a solid article by Dennet; it should provide a state of the art picture of the physicalist approach to consciousness. Although we may scoff at Dennet, there is a lot to appreciate in this article.
Facing up to the hard question of consciousness
I'm particularly interested in what
@USI Calgary thinks about this first powerful point in light of his own quasi "physicalist" approach to consciousness:
"The causes of the misdirection can be uncovered by reminding ourselves of a few largely uncontentious but easily neglected discoveries of neuroscience:
- (i) There is no double transduction [5]. The various peripheral and internal transducers—rods and cones, hair cells, olfactory epithelium cells, stretch-detectors in muscles, temperature-change detectors, nociceptors and others—are designed by evolution to take the occurrence of physically detectable properties as input and yield signals—axonal spike trains—as output. There is no central arena or depot where these spike trains become recipes for a second transduction that restores the properties transduced at the periphery, or translates them into some sort of counterpart properties of a privileged medium. Vision is not television, audition does not strike up the little band in the brain, olfactory perception does not waft aromas in any inner chamber. (Nor, one had better add, are there subjective counterpart properties, subjective colours-that-are-not-seen-with-eyes, inaudible-sounds, ghost-aromas that need no molecular vehicles, for us to enjoy and identify in some intimate but unimaginable way.) Colour vision is accomplished by a sophisticated system of information processing conducted entirely in spike trains, where colours are ‘represented’ by physical patterns of differences in spike trains that are not themselves colours. The key difference between the transmission of colour information by a DVD and the transmission of colour information by the various cortical regions is that the former is designed by engineers to be a recipe for recreating (via a transduction to another medium) the very properties that triggered the peripheral transducers that compose the megapixel screens behind the camera lens, while the latter is designed by evolution to deliver useful information about the affordances that matter to the organism in a form that is readily usable or consumable [10] by the specialized circuits that modulate the behaviours of systems external and internal."
The first is something
@smcder and I discussed intensely over the past couple months. Perception does not restore the properties transduced at the periphery.
After this Dennet writes:
"I have discovered that it is useful to pause at this point and invite readers to consider whether or not they actually agree with these two basic points, because their implications are highly destructive of commonplace presumptions."
The second point—the one I'd like to hear
@USI Calgary 's response to if he'd like—is: spike trains are not themselves transduced into properties of a privileged medium (i.e. phenomenal consciousness).
I believe
@USI Calgary 's stance is that spike trains (or some other brain activity) is transduced into some type of conscious field, akin to a magnetic field.
Dennet is arguing (and has for years) that consciousness just is the activity of the nervous system.
He says:
(ii) So, there is no place in the system for qualia,
if they are conceived of as intrinsic properties instantiated by (as contrasted with represented by) some activities in the nervous system."
So, I agree with Dennet that processes of the nervous system don't instantiate a
new medium (consciousness). But in saying this, it's not enough to say that phenomenal qualities are representations within the nervous system. I certainly believe that they are, but Dennet hasn't explained how. He argues that they aren't instantiated (emergent from) the nervous system. But he hasn't explained how physical spike trains can be phenomenal qualities.
I'll see if he addresses this in the rest of the article.
If he doesn't account for how physical spike trains can
be phenomenal qualities, individuals will continue to argue that phenomenal qualities emerge
from spike trains.