On 16/10/2015 8:56 am, Jason Resch wrote:
On Thu, Oct 15, 2015 at 12:34 AM, Bruce Kellett
<[email protected] <mailto:[email protected]>> wrote:
What evidence do you need to say that something does not exist?
Absence of evidence is, in this case, evidence of absence.
Why is that so in this case, when the standard form of that phrase is
"Absence of evidence is not evidence of absence"?
Because if there is no evidence for something where one would, if that
thing existed, expect evidence, then one is justified in saying that the
thing does not exist. If there were an elephant in my room at this
moment, I would expect to see it when I turned round. The fact that I do
not see an elephant when I turn round is good evidence that there is no
elephant in my room. Absence of evidence is evidence of absence.
Also, despite your claims to there being no evidence, there is in fact
evidence of platonic computations. They exist independently of you,
mean, and this physical universe, as surely as "7 is prime" is true
independently of you, me and the physical universe.
The statement "7 is prime" is true by virtue of the axioms of arithmetic
and the definition of a prime number. That does not imply that "7"
exists in any sense whatsoever. You confuse "true" being used of a
proposition, with "exists". That is a profound and serious confusion.
In mathematics you have descriptions of Turing machines and
descriptions of computations, but no live machines or
computations.
There are both.
What evidence do you have for this assertion?
The existence of a UD implies a quantum reality, and we observe a
quantum reality.
Accepting the truth of arithmetical systems like the axioms of
Peano/Robinson arithmetic, implies their existence.
But I do not accept the 'truth' of these mathematical structures. And,
even if taken as a set of axioms upon which one can reason, they do not
imply that anything like a UD actually exists in any useful sense. The
UD is an idea in platonia, and it is totally without function until it
receives a physical implementation.
Substrate independence simply means that you can replace all or
part of the human brain with computer-based equivalents. In other
words, strong AI. No need for platonia in order to say that
consciousness is independent of the substrate.
But if it is independent of substrate, and if computations exist
platonically, then those platonic computations are equally capable of
instantiating consciousness.
You are confusing the meaning of 'substrate'. In the context, I meant
an explicitly physical substrate. Platonia is an idea,
If Platonia is an idea, then so is "The primary physical reality". It
is up to science now, to determine which of these two ideas is more
likely to be true.
Sure. And science has proved many times over that physical reality
exists and can be operated on, while platonia is an idea that has no
useful consequences whatsoever.
it is no more 'physically real' than is the idea of a unicorn, or
of Hogwarts School.
Of course it isn't physically real. But why assume physical existence
is the only kind of existence? That seems to be an idea based purely
faith.
Neither unicorns nor Hogwarts can instantiate consciousness. No
more can the idea of platonia.
The idea of platonia doesn't instantiate consciousness, but objects
within platonia do.
Prove it by showing me this magical platonic conscious being.
If you want to demonstrate that the idea of platonia can sustain
consciousness of itself, then all you have to do is produce a
conscious being that does not have an accompanying physical
substrate. Until you do that, I think you should shut up about
platonia.
Would you demand of Everett to produce a conscious being from another
branch of the wave function, or else shut up about the other branches
of the wave function?
Yes, of course. The other branches of the wave function are not real
in any useful sense. They are an idea, just as is platonia. And ideas
can have effects in the real world only through the intermediary action
of conscious physical beings, never by magic.
If not, then why demand that I shut up about the consequences of
well-accepted theories?
Well-accepted?
Why? Arithmetic is system of propositions. Whether it is real
or not has no effect on Church-Turing.
Then you should be equally happy to have your brain implemented by
"unreal computations" as "real computations" :-)
Computations in platonia are 'unreal' -- they do not exist, so cannot
implement anything.
You said earlier that you have no evidence that objects of platonia do
not exist. So why insist so adamantly that they do not?
You should learn to read. I said no such thing. I said that the absence
of evidence for platonia was evidence that it did not exist.
Are you familiar with Max Tegmark's idea that physical existence is
mathematical existence?
* https://en.wikipedia.org/wiki/Mathematical_universe_hypothesis
* http://arxiv.org/pdf/0704.0646.pdf
*
http://www.amazon.com/Our-Mathematical-Universe-Ultimate-Reality/dp/0307599809
I am familiar with Tegmark's ideas. I do not agree with most of them.
Arguments from authority do not carry weight here. Tegmark is an
outsider in the physics community.
Bruce
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