Billy T: Your Essay on free will is interesting & informative. I agree with your views on mammalian visual systems.
Thanks, glad you liked it. Also thanks for reading its 8 or so pages, few do. (Unfortunately, we live a world dominated by 15 second "sound bites" on TV. They even stress the attention span of most.)
...I am not convinced that your arguments provide a strong argument for free will, ...
Nor am I. In fact, I tend to think genuine free will is an illusion. I.e. humans are really just very complex biological machines, with some innate programs and many things learned especially in the first two years of their life. I only note that it need not logically* be impossible if we are non-material constructs in a simulation as only material things (and energy flows) are governed by the natural laws.
I would not call the perceptual image generated by our brains a simulation, ...Whatever one calls the process, you seem to have described the essence of it.
Although it was via my effort to understand how a visual 3D perception is created from 2D stimulation of the retinas that lead me to my POV about perception, the "simulation" I suggest that we perceive is about EVERY aspect that we have sensor for. (It does not include the radio waves passing around and thru our bodies as we lack sensors for them, etc.) I.e. I call it a "simulation" for that reason - We internally simulate (in parietal brain tissue, I am certain) the ENTIRE environment we can sense, and extrapolate slightly ahead to compensate for the neural progressing delays (mainly caused by time required for diffusion of neuro-transmitters across the "synaptic gaps.") so it is a "real-time" simulation of the world we sense.
I do not think that this parietal simulation actually has any representations in it that could be called "images." Even in the primary visual cortex, V1, where there certainly is a "one-to-one" conformal mapping of the retinal stimulation into neural activity, calling that neural activity an "image" is controversial. I have a thick book, called "mental images" from about 25 years ago when this controversy was hotly debated in the cognitive science literature. (I have not kept up with that literature for more than 16 years - since moving to Brazil - so do not know current POV. I bet neither side persuaded the other, but both just grew tired of the discussion.)
... Consider viewing brick walls. ... My conscious mind seems to be viewing an image precise enough for me to actually count the individual bricks in any wall I face. ... I doubt that the band width of the optic nerve and the processing power of my brain is sufficient to create the image in real time from the incoming data. ... I am sure that much of the apparent preciseness is due to the memory of other brick walls....
Correct on all this. Usually instead of bricks, and related to the "mental image controversy", one is told to "Imagine a tiger in profile view." "Do you have a sharp image of it?" - "Yes, especially with my eyes shut." "Good, now count the strips for me." - The subject never can.
The simulation is not as detailed as we think it is. IMHO, there may not even be any image in the real time simulation. Instead we may just have a set of facts "tied together" that we associate with a tiger, with the computer I perceive now, etc. for the whole 3D world I perceive with my eyes open. I do not know, but lean towards this "no image" POV because we do perceive many facts that are not visible. Generally they are called "affordances." For example, when I perceive a red apple I also know the interior is white and it is food I can eat, etc. It does seem perception is more than surface deep but this is getting into a level of detail about the nature of the parietal simulation I wish to avoid comment on as I would just be guessing.
Yes, the remainder of your post is true - we fill in much with our memory and/or "reasonable expectations." There is a nice simple visual experiment showing this. A piece of graph paper, not too finely divided is best, that you can make two small spots on, perhaps 2 or 3 inches apart and look at with one eye closed. When in the position that one of the two spots is falling on the fovea and the other on the "blind spot" (optic nerve entry point) you will see only one spot and an otherwise complete set of graph paper lines - That is you have filled in with the graph's regular lines all of the region falling on the "blind spot." We do this "filling in" of vision all the time when ever one eye is closed. I.e. with one eye closed there is no perceived black spot in the field of vision. And as you note, we do it for all the senses with possible exception of taste and smell.
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*The simulation is taking place in the most capable computer that exists, but still there may be rules of its operation. I.e. the parietal brain computer making the simulation cannot be a Von Neumann machine, not a parallel processor of any type yet conceived by man. It certainly is not rigid rule following "fuzzy logic."
The main weakness of my argument that being non material creatures living in a simulation provides at least the possibility of genuine free will being real is here. I.e. by what set of rules is this parietal computer operating? I do not know the answer (and that is why I suspect genuine free will probably does not exist.). If there is an answer, I am inclined to think that logic does not have any "truth value" for at least some of its (declarative) statements.
For an example of such a declarative statement with no "truth value" (neither true nor false) consider:
"This sentence is false."
Note this four word example is in the class of "self referencing" statements. I think it likely that if genuine free will does exist, then there will be a lot of mutually self referencing activity of the parietal neurons, too complex for man's current understanding of their logic.
