OK, this is a *thought* experiment only - Please do NOT raid my basement - also, it's going to take a while to explain properly, so please bear with me on this one...
NB: In what you are about to read, I have tried to keep the wording entirely matter of fact, it may sound cold, dry and morally repugnant, but I want to try and put across a hypothetical situation and then ask you to consider the results...
Take two babies - both might be newly born, but preferably we'll start observing them whilst they are still in the womb. Place one baby in an artificial, but womb-like environment - big glass tank full of warm nourishing fluids, breathing noises etc. Where the temperature, chemical makeup, everything possible has been geared so as to make the transition as unnoticeable as possible - making sure all its body functions are fully supported. Leave the other baby to develop naturally.
Both baby's minds are developing in their respective wombs, they both respond to noises they hear and sensations they feel in their respective wombs. They kick, punch, and have periods of relative activity and rest. Essentially they should be pretty equivalent at this point (assuming we've done a good enough job on the artificial womb).
Now our natural baby gets born. Everything in his world is turned (quite literally) upside-down - temperatures fluctuate, lungs breath air, his sustenance is now provided via a complicated process of groping, sucking, swallowing and digesting rather than the much more convenient method of having 'food' piped directly to the bloodstream. Noises are happening all the time, lights flash, dimly discernable things drift into and out of his visual range (not that he knows what any of these things are yet) All in all, it's a pretty lively time compared to the warm comfortable softness of the last 9 months. This liveliness kick starts natural baby's mind into overdrive, trying to process all this data and turn it into some kind of meaningful information. Associations are made. e.g. The smells, sights, sounds, sensations and tastes are grouped into a certain-smelling, smiling-faced, cooing, warm, milky thing called Mum.
A normal baby has a lot of sensual data to deal with, and it takes a great deal of effort to put it all together into a meaningful set of associations. By meaningful, I of course mean things that make the baby feel physiologically good. If a baby feels cold, it will want to be warm, if it feels hungry, it will want to be fed, if it feels bored, it will want stimulation, if it feels over-awed, it will want quiet etc. The normal response for an unhappy baby is for it to cry out until it has its needs served by someone else. There must be a set of 'hard-coded' feelings that makes baby feel good/bad, and mental development is a matter of learning how to gratify these feelings by itself rather than having to rely on a carer who isn't always going to be around out there in the big wide world.
Our tube-baby's birth is rather different. We keep the baby in the flask, but provide it with an array of flashing lights, temperature changes, loud noises and other provocative (certainly no more disturbing than the real experience of being born) stimuli. However, there are some major differences. A tube provides air to it's lungs, everything it sees is displayed on a mask placed over its eyes and it remains suspended in it's liquid environment. Again this child’s brain will attempt to make sense of the (much less richly stimulating) world around it.
It's a reasonably widely accepted fact that what we experience at this stage of our development moulds our brains and makes us able to understand what our senses tell us. Mice who's whiskers are kept trimmed at this stage are later unable to use them as sense organs to the same extent as regular mice. They effectively become 'whisker-blind'. In the same way, our baby is unlikely to develop very good sensual processing areas in its brain for those senses it is unable to use (hearing, touch etc) Meanwhile, it's brain is going to be able to concentrate on making sense of the light patterns it can see on it's screen. This means that the senses that we might take for granted, if not used will atrophy, while those that are stimulated meaningfully will grow and develop.
In order for the tube-baby to make sense of it's sensorium, we need to give it meaning. So, when the baby is hungry, we flash a certain combination of lights, and only when the baby responds in some simple way, do we provide it with what it wants. (Quite how to establish a meaningful set of representations with which to communicate to an infant in this situation is a huge task, but I'd ask that you allow me this shortcut and assume that we've worked out a suitably workable method) We also need to allow our baby to communicate with us somehow, perhaps by tracking its eye movements, or by the means of some basic implant (again unfortunately I don't have the details I'd like here, so would ask that you bear with me)
So while the normal child is busy processing information about its natural world, our tube baby is doing the same, only the information available to it is entirely controlled, and limited to the images it sees on the screen, and what it hears and feels in its tank (which we of course try to keep to a minimum). In addition, we carefully monitor our tube baby's physiology, translating it into a pattern of lights, which are relayed back to the child’s screen. Over time, and with little else to think about, it should be able to learn to regulate it's entire physiology, translating what it sees on the screen into some form of understanding.
Instead of a mother figure providing relief to unpleasant physiological stimuli, we use a certain frequency of flashing light, over time this frequency will become comforting. Since the child is aware that it can in some way control the stimuli it sees, it will try to determine what it can do to maintain the flash at the same frequency. We place mathematical puzzles in the form of lights for the baby to solve - since it has nothing else to focus on, these should be very easy - in the same way that autistic children, who find the world terrifyingly over-complex, retreat into the simple, logical worlds of mathematics, or representation (drawing, painting etc). As our child's mind learns to live in this (very strange) artificial world, the senses it doesn't use will likely atrophy with disuse until over time, it may be entirely unable to feel touch, sense smell or taste etc. At the same time, the purely logical information we present and collect will have the full brain's attention, the brain will become tuned to solving, or dealing with this kind of problem - we will have built a living computer.
There are a number of questions this line of inquiry poses:
Is the mind really this plastic? Would we think of this thing as a child, or a some kind of super-powerful computer? Would we have created a logical genius? A gruesome monster? Would this child have any form of emotion? Would we be able to communicate (as in discuss, or hold a meaningful conversation) with it? Would it have a soul? Would it have a notion of 'I'?
When thinking about this, bear in mind recent experiments involving animal neural tissue (
linked to here) where pieces of rat brain were trained to control a simulation of a plane flying. There are other instances where animal brain tissue was used to control simple pieces of machinery.
Once again, I'm not suggesting that we try this out, nor am I saying that I don't find the idea abhorrent and against everything I value, but what I am asking is whether this is possible, and if it is, what does it say about us as biological machines, and if it's not, why not?