On 14 May 2015, at 08:12, Bruce Kellett wrote:
meekerdb wrote:
On 5/13/2015 10:25 PM, Bruce Kellett wrote:
meekerdb wrote:
On 5/13/2015 5:32 PM, Russell Standish wrote:
On Thu, May 14, 2015 at 11:26:17AM +1200, LizR wrote:
On 13 May 2015 at 18:20, Russell Standish
<[email protected]> wrote:
For a robust ontology, counterfactuals are physically
instantiated,
therefore the MGA is invalid.
Can you elaborate on this? ISTM that counterfactuals aren't,
and indeed
can't, be physically instantiated. (Isn't that what being
counterfactual
means?!)
No - counterfactual just means not in this universe. If its not
in any
universe, then its not just counterfactual, but actually
illogical, or
impossible, or something.
If "not in any universe" is meant in the Kripke sense, then
something not in any universe is something that is logically
impossible. But if "not in any universe" is meant in the MWI
sense, then counterfactuals are only those outcomes consistent
with QM but which don't happen. I think it is only the latter
kind of counterfactual that need be considered in computations.
No. The counterfactuals that Bruno refers to in comp seem to come
from the "If A the B else C" construction of computer programming.
This puts no restriction on the worlds containg B and C.
That would seem to create conundrums. The counterfactual is A
taking a value other than the one it actually did. A is one of the
inputs to the prosthetic brain part, so in practice the doctor
would only consider a finite number of values of A that could be
realized by the sense organ or other brain parts that realize it.
But if A can be anything from platonia it could be "If this program
X halts..." or "The smallest even integer not the sum of two primes."
If you read around the typos in my post above, the counterfactual
if...then...else... construction branches on the input A, which is
not necessarily *anything* at all, just what the program encounters.
It is B and C that can be anything that the programmer wants them to
be. We are talking computing here, not physics.
Indeed.
That is why the other worlds of MWI have nothing to do with
counterfactual correctness.
Yes and no, as it is a very difficult subject. The problem is mainly
for the past false situation, like: as the following sentence any
meaning: "if Hitler did not born, the Nazis would have got the atomic
bomb before the others, in 1960."
Now, with the MWI, + ultra-quantum computer, we might imagine a day
where detailed quantum emulation of that part of the earth might
suggest that in 80% of the realities with Hitler not born, the nazi
(sometimes with another name) got the Atomic bomb before the others,
and in 30% of the situation used them.
The normal reaction, before such technology exists, is in the french
saying: "avec des si et des mais on mets Paris en bouteille" (with if
and but we can put Paris in a bootle).
So the MWI might still have relations with some type of
counterfactuals. Like comp itself, as you can know that you would have
done something differently, you would belong to different
computations, most plausibly.
Note the ethical problem: can we simulate earth at the substitution
level of its inhabitants?
Bruno
Bruce
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