Re: Does Man Have Free Will?

From: Bob Casanova <nospam@xxxxxxxx>:
On 08 Mar 2008 10:40:13 GMT, the following appeared in
talk.origins, posted by none@xxxxxx (Eric Rowley):
From: Bob Casanova <nospam@xxxxxxxx>:
On Thu, 6 Mar 2008 17:00:39 -0800 (PST), the following
appeared in talk.origins, posted by Sonofagunzel
<soasoag@xxxxxxxxxxxx>:

<snip>

Invent a time machine, and put the video in it. Send it to
the other side of the world, and have someone watch it seconds
before the actual event takes place. That person knows what
the choice will be before the choice is made.

Why have we now disproved free will?

You haven't.

But in his thought experiment I think he has.
(I.e. he would if he performed his experiment with the results
he thinks he'd get.)

Yes, under the conditions he described he has; I was
incorrect, and answered based not on the stated conditions
but on my belief that those conditions would be impossible
to implement. My error in treating a hypothetical as
possible (which *really* irritates me when it's done to me
for one of my own hypotheticals; sorry 'bout that...).

I don't know which is right or wrong, my main reason
for pointing out this option was that I think it keeps
the discusion moving in a more interesting direction.

Your assumptions are:
1) Time travel into *the*, *not *a*) future is possible.

I don't see any time travel into the future, but I think the
normal method of getting there suffices for your point.

Oops. Not really sure where this one came from; I have to
assume I had a brain fart and conflated at least two trains
of thought.

2) It's possible to return from the future.

3) There is only one universe (sort of implied by 1) ).

Well, we only have access to one universe there could be
others as long as they are compleatly separate.
(Not alternate futures.)

That's why I specified below that the Many Worlds
interpretation would need to be incorrect.

1) and 2) *assume* determinism,

1) does, I don't see it for 2)

See below (nsgre gur EBG13).

since both require the
future to be as fixed as the past.

Sort of, 2) allows the future to be as mallable
as the past. He's already changed the past by sending the time
machine, which wasn't there "before", and the changed past ought
to influence the future.

...unless the entire sequence was "always" part of the
continuum. Again, this requires determinism.

And some unusual view of time, I think, where was the time machine
stored the first time through the loop, and where is the time-
machineless past on the second pass.

And wouldn't the normal view of determinism exclude time travel?
Maybe I'm confusing determinism with causuality, but we've got a
time machine popping up where/when it has no direct cause, sure ,
ultimately we can see the "seeds" of a cause but no imediate
cause.

Notice how careful Sonofagunzel was to specify a scenario where
his time machine and video couldn't directly influence the
customers before they made their choices.

I think the combination of 1) and 2) might assume something
that "outdetermines" determinism as it is normally defined.
Something like the world in Terry Pratchetts "Mort" "healing"
itself and rejecting changes in it's predetermined history.

(Ab gvzr geniry vaibyirq, whfg fbzrbar abg orvat qrnq jura gurl
jrer fhccbfrq gb or.)

Vagrerfgvat vqrn. V unira'g ernq zhpu Cengpurgg, ohg V'ir
ernq n ybg bs bgure zngrevny, obgu svpgvba naq aba-svpgvba,
qrnyvat jvgu gvzr geniry naq gur vaurerag vanovyvgl bs
Ratyvfu gb unaqyr gur grafrf, *rfcrpvnyyl* vs nygrengvba bs
gur cerfrag/shgher ol punatvat gur cnfg vf cbffvoyr.

3) assumes that the *only* future which can be visited,
and from which one can return, is that of a lineally-
progressing universe;

But not necessarily one that can't be changed by time travel.

Hmmm... I think I see where I went wrong; I was
subconsciously assuming that there were basically two
choices:
1) There is no macro effect from the probabilistic nature of
QM, and therefore every event is fully determined by
preceding events; this results in determinism.

And probably excludes time travel.

2) There *is* a macro effect from QM, and this results in a
"many worlds" scenario; all decisions go all possible ways,
and therefore it's essentially impossible to return to the
same past one left.

Past or future?
There would certainly be an infinate number of pasts but
depending on the nature of time travel it might only be posible
to return to ones that were "ancestral" to ones own present?

Perhaps not though, one could almost certainly get around such a
limitation by simply going back further and changing the choices
that led to the "original" later past :-)

But there's a third (at least; there may be more)
possibility: There's a macro effect from QM, but "many
worlds" is *not* correct; there's only one universe, and
while the past is fixed the future isn't (IOW, an unfolding
and solidifying decision sequence). In this scenario (unless
I'm missing something) it would be possible (actually,
"required") that one return from the "a" future to the
original past, but since the future wouldn't be fixed normal
progress through time is *not* guaranteed to arrive at the
previously-visited future. However, in this case I'm not
certain that futureward time travel would even be possible,
since how can one visit a universe which hasn't actually
come into existence yet?

Shunt the time machine onto a siding and wait for time to
catch up? ;-)
(And hope that time doesn't pass at the same rate inside the time
machine, cf Ian Watsons's "The Very Slow Time Machine")

On the other hand, how could one receive a visit from a future
that hasn't actually come into existence yet?

I think that time travel, in either direction, requires a rethink
of the nature of time, scraping the idea of a priviledged "now"!

"Now" would have to be nothing more than where you happen to be
on the timeline, no more the "real now" than your current
geographical position is the "real here".

And this rethink would almost certainly have to involve some
version of "many worlds".

However, there was an article in Scientific American many, many
years ago that suggested that a way to avoid paradoxes would be
a variant where the branching was caused by time travel itself,
time travel involved "looping back" but not attaching to the past,
but rather continuing on a "parallel track".
So the grandfather you kill isn't the one that has to survive in
order for you to be born and invent the time machine.

Though this might not actually require time travel as such, maybe
you could switch over to a timeline that was "out of sync" with
your original one thereby preserving the "priviledged" now, the
fixed past and the not yet existing future.

(Actually, there's at least one more possibility: There's no
macro effect from QM, but results do *not* proceed directly
from causes. I reject this one out of hand.)

"many worlds" is false.

Now, instead of the time machine, you have a gun. Stand
outside the restaurant, and threaten to kill anyone who
doesn't buy a strawberry shake. Better still, give yourself
the power to create those people and the circumstances
leading
up to their choice, and make it so that
they want strawberry shakes.

...which yields determinism, which I reject.

Me too.

Now have we disproved free will (or at least demonstrated a
potential inconsistency between God and free will)? Yes.

Not really;

But if he could do what he suggests, he would disprove free
will wouldn't he?

Yes, but since I reject determinism I have to also reject
the idea that his scenario is possible to implement.

And I think his thought experiment does show that the view of
God as a being who knows every detail of all future events is
incompatable with free will.

Agreed.

where does QM come in?

It's obviously incompatable with his scenario.
(Unless it has some underlying reqularity.)

I believe that this (underlying regularity) contradicts the
very nature of uncertainty which is inherently
probabilistic,

Probably ;-)

But surely without a time machine we can't be _completely_
certain that this isn't some kind of psudouncertainty?
Like the psudorandom number generator in a computer, generating
what appears to be random events but if the "tape" is rewound
the same sequence would be generated every time.

but I'm no physicist; all I know on the
subject is from my undergrad physics courses and the little
I've read since.

(BTW, if you're interested in a fairly readable book dealing
with QM and the multiverse [and the evidence it exists] I'd
recommend _The Fabric of Reality_ by David Deutsch.)

Thanks, I'll look into it.

<snip>

Eric

.