On Tue, Jan 22, 2013 at 1:09 AM, Craig Weinberg <whatsons...@gmail.com> wrote:

>> Do you disagree that swapping a carbon atom for another carbon atom in
>> the brain will leave brain function and consciousness unchanged?
> I don't believe that we will necessarily know that our consciousness is
> changed. Even LSD takes a few micrograms to have an effect that we notice.
> Changing one person in the city of New York with another may not change the
> city in any appreciably obvious way, but it's a matter of scale and
> proportion, not functional sequestering.

>> The field of nuclear medicine involves injecting radiolabeled
>> chemicals into subjects and then scanning for them with radiosensitive
>> equipment. This is how PET scanners work, for example. The idea is
>> that if the injected chemical is similar enough to normal biological
>> matter it will replace this matter without affecting function,
>> including brain function and consciousness. You could say this is a
>> practical application of the theory that consciousness is
>> substrate-independent, verified thousands of times every day in
>> clinical situations.
> That's because the radioactivity is mild. Heavy doses of gamma radiation are
> not without their effects on consciousness. Anything that you do on the
> nuclear level can potentially effect the chemical level, which can effect
> the biological level, etc. These levels have different qualities as well as
> quantitative scales so it is simplistic to approach it from a
> quantitative-only view. Awareness is qualities, not just quantities.

Obviously, if the change you make to the brain changes its function it
could also change consciousness. This is the functionalist position.
You have claimed that this is wrong, and that no matter how closely a
replacement brain part duplicates the function of the original there
will be a change in consciousness, simply because it isn't the
original. If this were so, you would expect a change in consciousness
when atoms in the brain are replaced with different isotopes, even if
the isotopes are not radioactive. And yet this is not what happens.
The scientific explanation is that chemistry is for the most part
unaffected by the number of neutrons in the nucleus, and that since
the brain works by means of chemical reactions, brain function and
hence consciousness are also unaffected. It's not that there is
anything magically consciousness-preserving about switching isotopes,
it's just that switching isotopes is an example of part replacement
that makes no functional difference, like replacing a part in your car
with a new part that is 0.001 mm bigger.

Stathis Papaioannou

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