On 07-10-2015 02:04, Brent Meeker wrote:
On 10/6/2015 4:35 PM, smitra wrote:
On 07-10-2015 00:06, Bruce Kellett wrote:
On 7/10/2015 7:51 am, Brent Meeker wrote:
On 10/6/2015 1:18 PM, Stathis Papaioannou wrote:
I'm not sure I understand what you are getting at. I meant that if
the normal sequence of brain states is s1-s2-s3 with corresponding
mental states m1-m2-m3 and s2 is omitted, there is nothing in m3 to
give any indication of the discontinuity. Of course, normally s2 is
necessary in order to generate s1, but that doesn't change the
argument.
But I think that's wrong. Brains are not like ideal von Neumann
computers or Turing machines that have "brain states" corresponding
to "mental states". If you simulated a brain using a computer you
would find that an enormous number of "brain states" were required
to instantiate a single conscious thought and furthermore the brains
states necessary for one thought overlapped with those necessary for
the next thought. So this overlap at the low level is part of the
physical continuity needed for consciousness. The fact that the
physics can be simulated by discrete computation doesn't imply that
the conscious states are discrete.
I think that is an important insight, Brent. One thing that it means
is that two brains can, by chance, be in the same physical state at
one instant, but those two brains might be supporting quite different
thought processes. The consequence is that there is one person per
brain -- the same person can't be spread over several brains.
Bruce
That's impossible, two identical physical states within an isolated
system will yield the same (statistical) results when measured. So, if
one person would be experiencing something different compared to the
other person at that very instant then, by definition, they were not
in the same physical state at that very moment, because that's how we
define physical states to begin with.
No, the contention is that a physical state, a state that obtains at a
single moment (Planck time?), does not instantiate a thought or an
experience. A thought or experience requires a sequence many physical
states and having two sequences share some subsequence of states is
not enough to make the two experiences the same. Consider an airport:
the fact that two runways cross doesn't make them the same runway.
Brent
Yes, this is the "observer moment problem" discussed a long time ago in
this list, but the requirement of needing a sequence of states is also
problematic, because at any given time I'm a conscious being. This
paradox is related to the well known paradox where one argues that you
can map the states of the brain of a person as it evolves in time to
that of a clock and then ask why the clock isn't conscious.
Of course, the clock doesn't perform any computations, but to see this
you have to consider the counterfactual inputs and the corresponding
counterfactual outputs. Then as I've argued here one or two years ago,
a much better solution is to invoke the MWI. Given your conscious
experience, your brain can still be in an astronomically large number of
states. So, instead of identifying yourself with the single branch, you
should consider the very large bundle branches that contain the same
macroscopic information.
The superposition of these states describes a person that is entangled
with the environment. This entanglement contains the counterfactuals
that you need to define what computation is performed at any given
moment.
But invoking the environment makes this a messy way out, a better way
i.m.o. is to include one computational step, you identify the operator:
O = sum over inputs i of |output(i)><i|
as your observer moment . The summation is over states that fall within
your resolution, and this then partially defines a computation.
Saibal
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