Stathis Papaioannou wrote:
> Brent Meeker writes (quoting SP):
>>>>Consider a computer which is doing something (whether it is dreaming or 
>>>>musing or just running is the point in question).  If there is no 
>>>>interaction between what it's running and the rest of the world I'd say 
>>>>it's not conscious.  It doesn't necessarily need an external observer 
>>>>though.  To invoke an external observer would require that we already 
>>>>knew how to distinguish an observer from a non-observer.  This just 
>>>>pushes the problem away a step.  One could as well claim that the walls 
>>>>of the room which are struck by the photons from the screen constitute 
>>>>an observer - under a suitable mapping of wall states.  The computer 
>>>>could, like a Mars rover, act directly on the rest of the world.
>>>The idea that we can only be conscious when interacting with the environment 
>>>is certainly worth considering. After all, consciousness evolved in order to 
>>>the organism deal with its environment, and it may be wrong to just assume  
>>>without further evidence that consciousness continues if all interaction 
>>>with the 
>>>environment ceases. Maybe even those activities which at first glance seem 
>>>involve consciousness in the absence of environmental interaction actually 
>>>on a trickle of sensory input: for example, maybe dreaming is dependent on 
>>>proprioceptive feedback from eye movements, which is why we only dream 
>>>during REM sleep, and maybe general anaesthetics actually work by 
>>>all sensory input rather than by a direct effect on the cortex. But even if 
>>>all this 
>>>is true, we could still imagine stimulating a brain which has all its 
>>>sensory inputs 
>>>removed so that the pattern of neural activity is exactly the same as it 
>>>have been had it arisen in the usual way. Would you say that the 
>>>stimulated brain is not conscious, even though everything up to and 
>>>the peripheral nerves is physically identical to and goes through the same 
>>>physical processes as the normal brain?
>>No.  I already noted that we can't insist that interaction with the 
>>environment is continuous. Maybe "potential interaction" would be 
>>appropriate.  But I note that even in your example you contemplate 
>>"stimulating" the brain.  I'm just trying to take what I consider an 
>>operational defintion and abstract it to the kind of 
>>mathematical/philosophical definition that can be applied to questions 
>>about rocks thinking.
> The brain-with-wires-attached cannot interact with the environment, because 
> all its sense organs have been removed and the stimulation is just coming 
> from 
> a recording. Instead of the wires + recording we could say that there is a 
> special 
> group of neurons with spontaneous activity that stimulates the rest of the 
> brain 
> just as if it were receiving input from the environment. Such a brain would 
> have 
> no ability to interact with the environment, unless the effort were made to 
> figure out its internal code and then manufacture sense organs for it - but I 
> think that would be stretching the definition of "potential interaction". In 
> any 
> case, I don't see how "potential interaction" could make a difference. 

Yet you had to refer to " if it were receiving input from the 
environment" to create an example.  If there were no potential interaction 
there could be no "as if".  So istm that the potential interaction can be an 
essential part of the definition.  That's not to say that such a definition 
is right - definitions aren't right or wrong - but it's a definition that 
makes a useful distinction that comports with our common sense.

>If you had 
> two brains sitting in the dark, identical in anatomy and electrical activity 
> except 
> that one has its optic nerves cut, will one brain be conscious and the other 
> not?

Where did the brains come from?  Since they had optic nerves can we suppose 
that they had the potential to see photons and they still have this 
potential given replacement optic nerves?  Not necessarily.  Suppose one 
came from a cat that was raised in complete darkness.  We know 
experimentally that this cat can't see...even when there is light.  The lack 
of stimulus results in the brain not forming the necessary structures for 
interpreting signals from the retina.  Now suppose it were raised with no 
stimulus whatever, even in utero.  I conjecture that it would not "think" at 
all - although there would be "computation", i.e. neurons firing in some 
order.  But it would no longer have the potential for interaction; even with 
its own body.

But I think you do bring up a good point - the boundary between "brain" and 
"environment" is clear enough for actual animals, but seems rather arbitrary 
in the abstract.

Brent Meeker

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