I'd say that the definition of "computer" is pretty simple. It's a device which can accept, store, and process data according to a pre-determined set of rules. Storing may not be absolutely necessary; I don't think it really matters for the purpose of this discussion, but there it is.
Well, the brain can accept data (the five senses), store it (memory), and process them according to a predetermined set of rules (various neurons and nerve clusters interacting).
What do you mean by "data"?
If I consider food "data", then my body can accept it, store it, and process it according to a predetermined set of rules.
But that seems odd to say because we normally use the term "data" to refer to sets of symbols -- to what we find in spreadsheets and on printed pages and burned into discs and such.
A baseball hitting you in the head is not generally considered "data". The number of beanballs a pitcher has thrown in his career (an abstraction) is condidered "data".
And because "data" requires abstraction, or encoding, it must be decoded -- if all intelligent life were to vanish from the universe tomorrow, our data would vanish with us.
So the problem with your model is that the brain's "input" is the equivalent of getting hit by a baseball -- it's just a whole bunch of physical bombardments.
No "data" goes into that organ of your body.
Once that organ is up and running properly, then we can talk about producing data, but not when we're talking about how the organ itself runs.
My PC, on the other hand, has been specially designed by human beings to help us handle data.
It lets us know that it arises from a complex system like the brain, can be altered by making changes to the rules or damaging the system, and can theoretically arise from artificial systems as well as natural ones.
But we already knew that consciousness arises from a complex system like the brain, because we already knew that it's a function of the brain. So there's no contribution on that count.
And we already knew that consciousness can be altered by physically manipulating or damaging the brain through lab experiments.
And we already assumed that this behavior, like all others, can (in theory, unless we discover different) be mimicked in some sort of other physical system, if properly designed and built.
We get all of this from observing the brain. So there are no contributions here.
I'm not entirely sure what you're arguing here. Or, rather, I'm pretty sure I understand what you're saying; I just don't get how it applies to the situation at hand.
Do you think that a robot could ever be conscious? Say that it was given analogues for the ear, eye, nose, mouth, hand, leg, and so on, as well as an artificial brain that could receive, process, and react to all this information in exactly the same way that a human brain could.
Would this robot be conscious? It has been "built", after all, and has the capability to "go somewhere" - experience and react to things. If you think it isn't conscious, why do you think that?
No, that's not my point.
Let me rephrase it....
As long as you're talking about signal-in/signal-out, it's fine to swap a computer out for some part of a system.
For instance, I can replace my car-body paint crew by replacing their brains and their arms with computers and mechanical arms.
That's because to run the paint sprayers I just need the computer to accept electrical signals in the right pattern and put them out in the right pattern.
That's why it's so (relatively) easy to build a machine that does what your knee does when the doctor taps it with a mallet.
Making your leg jump requires only that a nerve signal go up one line and trigger other signals that go back down another. (You do consciously feel what's going on, but you don't have to -- it's not necessary for the process to occur.)
So why can't I get a computer -- and a computer alone -- to haul my trash to the dump, or produce sugar, or filter my blood?
In other words, why can't I swap a computer (with only enough hardware to run the logic and nothing else) for my truck, or a leaf, or my liver?
It's because these processes are not just signal-in/signal-out... real work is required for these outcomes, even though they are all quite different in nature.
And although we don't know what it is yet, exactly, or how it's done, consciousness does not seem to be "signal out". (If it is, what is the signal and where is it going to, and how does it produce colors and sounds and smells and pain and such?)
In another thread I used this analogy to illustrate the point....
Suppose there's a town in a mountain pass separating the interior farmland from the port on the coast. All farms must go through this town.
Inside the town, there were various points where taxes had to be paid (in produce) and you might get "change" back in the form or other produce -- e.g. if you don't have a cantaloup to pay a tax, you pay a watermelon and get back two tomatoes.
Also, when farmers would meet at intersections, they would often barter among themselves.
The taxes changed all the time, and so did the barter, so you never knew what you'd end up with in your wagon when you left... you just had to wait and see.
So that's a vegetables-in/vegetables-out system.
But eventually, folks got tired of the traffic, so one day the mayor had an idea. They'd build a moat around the town, float all the farmers' crops and their wagons on barges from one gate to another, and give the farmers lists of their crops, both type and weight/number.
That way, they could do all their transactions on paper, and just pick up the right mix of veggies and their wagon on the other side.
Essentially, they've swapped an information system for a physical system.
But there's a catch... this only works if no real work needs to be done with the original inputs along the way.
(Think back to the truck and the leaf... you can't use a computer alone to substitute for either of these because the computer does symbolic work, and we need real work done here.)
So imagine if the mayor had contracted out the work of building a moat, but hadn't told the contractor why. And suppose he requested some sort of engine to make the moat flow in a circle.
The contractor thinks, "I know, there are weigh scales at every tax office and on every corner in town to facilitate the taxes and barter on vegetables... we'll capture the energy of the movement of the scales to make this moat flow."
So that's how he designs the system.
Well, now we're in trouble because the new information-based system can't do that work, so the moat doesn't flow.
As far as we know, consciousness is a direct result of the physical activity of the brain. We have no reason to believe otherwise.
As far as we can tell, the electrochemical activity in your brain directly results in behaviors like blue and green and pain and the smell of coffee and the feeling of disgust and the sound of birds singing.
Consciousness is not signal-in/signal-out.
Conscious phenomena are the result of real physical work by the brain, and if you swap it out with a computer which is only designed to "run the logic" and isn't built with the right hardware to actually make blue and green and pain happen, they won't happen.
That's why the comparison with the truck and the leaf is apt.
Here's a second way of thinking about it....
Suppose Major Tom is on a spacewalk to repair a space probe. When he's done, he sees there's a dangerous space squid between him and the mothership.
So he requests to be beamed back. They convert his physical structure somehow, preserve the information on how it's assembled, and re-assemble it back on the ship, and he's home safe.
But suppose he decides that the space squid is a threat to the ship, and he must kill it.
In that case, you can't convert to your information system... he has to go there himself in his suit and kill the thing.
You could, of course, beam him aboard and alter the information so that he appears in the same state he would have been in if he had killed the squid -- he'll be tired and a bit roughed up and he'll have a memory of killing the squid.
But the squid will still be there.
To actually do that work, you can't switch to an informational system.
That's why you can use a machine with a computer in it as a substitute for a liver, but you can't use just a computer with only enough hardware to run the logic, because real-world behavior can't be accomplished with logic alone.
That's why you can use a machine with a computer in it to do what my truck does, but you can't use a computer alone with only enough hardware to run the logic.
Ditto for a leaf... photosynthesis cannot be performed with logic alone.
There is absolutely no reason to think that the behaviors of conscious awareness are any different. They must require real work, not just logic.
ETA: That's where this "magic bean" nonsense comes from. The computational literalists believe that logic alone can create consciousness -- although they have no theory of how or why -- so they dub the physical process the "magic bean" since they think we don't need it.
