On 10/6/2015 8:11 PM, smitra wrote:
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,

Sure it does.  It computes the time.

but to see this you have to consider the counterfactual inputs and the corresponding counterfactual outputs.

Right. The problem is not that it doesn't compute anything, it's that it doesn't interact with its environment so it has nothing to be conscious of, except the time.

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.

I agree with that. But the hypothetical being argued was the inverse: Suppose two persons/brains were is exactly same state.


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,

But doesn't that just move the problem to determining which states are "yours".

Brent

and this then partially defines a computation.

Saibal


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