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[Neuroscience] Re: Philosophical Foundations of Neuroscience

jonesmat via neur-sci%40net.bio.net (by jonesmat At physiology.wisc.edu)
Wed Nov 29 16:51:33 EST 2006


John H. wrote:
> >
> > GS: Change. The brain is changed when animals are exposed to certain
> > environments and, as a consequence, they behave differently. It does not
> > follow that anything is "stored." And besides, that leads to a view that
> > Bennett and Hacker talk a lot about, and to which they give a (brilliant)
> > name: the mereological fallacy.
>
>
> JH
> To use a computer analogy(oh dear!)
>
> People typically say that a hard disk stores information. This is
> incorrect. A hard disk stores electronic switches which are meaningless
> in themselves. What is on a hard disk only becomes comprehensible when
> it is subject to the machinations of the whole computer AND we then
> interpret it.
>
> I often think that it is wrong to study memory as if it is some
> independent entity in the brain. "Memory" cannot exist by itself, it
> can only be functional within the context of all the other things we
> do. Hence for me, the distinction between "memory" and "cognition" is
> perhaps a conceptual convenience, though a very dangerous one.
>
> "Change" lacks informational value. The question for me is how that
> change becomes a perception. Perhaps this question is redundant.


Howdy,

Interesting discussion.

Might as well throw in my two cents.

Cent #1
I disagree with the whole "mereological fallacy" accusation against
"neuroscientists" in general.  First, no sensible neuroscientist would
argue that the brain acts in isolation from the rest of the organism.
At the very least, most people would agree that external stimuli coming
in through our sense organs have at least some influence on our
thoughts and behavior. So I don't think anybody is seriously saying
that the brain (the part) is the sole contributor to consciousness or
behavior (the whole). No mereological fallacy is being committed -
that's all just hype to make their book sound more provocative. Second,
the authors' apparent (I haven't read the book, just scanned the
reviews) utter rejection of the idea that psychological events or
properties or states or whatever can reasonably be said to occur in the
brain, and are essentially identical with functions of the brain, just
seems silly to me given the rapidly accumulating physiological data.

Here's an example. The NPDR review states the following:

"It is when Searle claims that "mental phenomena are caused by
neurophysiological processes in the brain and are themselves features
of the brain" (Searle, Rediscovery, p. 1) that Bennett and Hacker
demur. Searle's claim commits the mereological fallacy discussed
earlier. Brains are no more conscious than they are capable of taking a
walk or holding a conversation. True, no animal could do either of
these things without a properly functioning brain. But it is the
person, not the brain, that engages in these activities."

Now, consider the claim that brains are not capable of taking a walk or
holding a conversation. Ok, forget about the walk part for a minute.
But is a brain capable of holding a conversation? Modern experiments
suggest that the answer to this is almost certainly going to be "yes".
Signals recorded from electrodes implanted in a monkey's brain have
been used to direct the motion of cursors on a computer screen, or
robotic arms. Similarly, EEG signals from human brains have been used
to do the same thing, including using the cursor to write messages.
See this wikipedia entry for a brief summary of some of this research:
http://en.wikipedia.org/wiki/Brain-computer_interface.

If the signals produced in the brain and by the brain can communicate
information in the form of written messages, bypassing the rest of the
body, then the brain is capable of holding a conversation. If the brain
can hold a conversation on behalf of the "person" whose brain it is,
then it will pass all of the other tests for being "conscious" that the
"person" would need to pass. If we allow the use of robotic legs
instead of arms, then in principle the brain is also capable of taking
a walk.


Cent #2
Regarding computer analogies and the definition of information:

John H. wrote:
> People typically say that a hard disk stores information. This is
> incorrect. A hard disk stores electronic switches which are meaningless
> in themselves. What is on a hard disk only becomes comprehensible when
> it is subject to the machinations of the whole computer AND we then
> interpret it.

Not to pick on you John, but this is a common sentiment, so your
bringing it up gives me a chance to mention a few points.

Let's avoid the term "information" for a just a moment. Would you
object to the following statement:

"A hard disk stores sequences of ones and zeros (or A's and B's or
pluses and minuses or whatever binary symbols you want)"

If your answer is "no, I don't object", then consider that there are
mathematical theorems proving that a) any signal whatsoever can be
represented by sequences of ones and zeros, b) most quantitative
definitions of the word "information" revolve around statistical
comparisons between two ensembles of signals (e.g., a set of signals
that is "sent" and another set that is "received"). Therefore, if I can
write sequences of ones and zeros on a hard disk (i.e., "sending" those
signals to the disk) and then later read some signals back from the
disk (i.e., "recieve" signals from the disk), and if the received
signals correlate well with the sent signals in a certain way, then I
can prove mathematically that the hard disk stored a certain amount of
information (using for example, the Shannon definition of information,
but nearly all other quantitative definitions would also work).

Note that I don't need to know what the sequences "mean". They could be
English text (which I might or might not understand), or Japanese text
(which I definitely won't understand), or purely random digits (for
which understanding is not possible at all). My understanding or
interpretation of the signals does not affect the amount of information
that was sent, stored and received. My not understanding Japanese has
no bearing on the amount of information that can be conveyed in that
language. Similarly, I don't (consciously) understand the patterns of
activity in my brain. That has no bearing on the fact that information
(in the quantitative sense) is being sent, stored and received by my
neurons all the time.

  

But that's just my two cents.


Cheers,

Matt



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