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From: Kory Heath <kory.heath.domain.name.hidden>

Date: Sun, 25 Apr 2004 05:45:38 -0400

At 10:36 AM 4/24/04, Stathis Papaioannou wrote:

*>Does the fact that we never find ourselves in one of the bizarre,
*

*>inconsistent worlds that are postulated to exist in Platonia cast doubt on
*

*>the reality of these worlds and the validity of the underlying theory?
*

Not yet. We know that the bizarre, inconsistent worlds must exist if the

Platonia idea is correct, but we (or at least I) don't currently know how

likely they are. In Platonia, there are X number of possible-next-states

from my current state. (For simplicity's sake, lets even say that X is a

very very large finite number.) If a vast majority of these states show me

sitting in my chair typing, with my computer not turning into a kangaroo,

etc., then no, the fact that my world so far has not been bizarre and

inconsistent does *not* cast doubt on the validity of the Platonia theory.

In fact, if we can show logically, mathematically, or computationally (for

me these are all ultimately the same thing) that a vast majority of my

next-possible-states do in fact show me sitting in my chair typing, with

very few computers turning into kangaroos, this would be an extremely

strong reason to believe that the Platonia theory is correct, because it's

survived a rather stringent falsification test.

Note that the tests we need to perform - tests like "how many of my next

possible states show me still sitting in my chair? How many of my next

possible states show my computer turning into a kangaroo?" - are logical /

mathematical / computational ones, not empirical ones. We already have the

empirical data, which we call "the laws of physics". We need to know what

the Platonia theory actually predicts, and compare it to the empirical

data. For my part, I don't actually know what the Platonia theory predicts,

because I have no idea how to go about addressing the question

mathematically. Bruno Marchal says we need to create a better model of what

counts as a platonistic observer, and "interview it" about its relative

consistent extensions (what I've been calling "next-possible-states"), and

find out what regularities it would see. To me, that's just another

statement of the problem. I don't have a very good model of what counts as

a platonistic observer, and I don't know how to determine the structure of

its next-possible-states, etc.

If we make progress on this issue, and we come to the mathematical

conclusion that the probabilities we're looking for *don't* exist in

Platonia - that is, if we determine that (say) my next-possible-states in

which my computer turns into a kangaroo are just as common as those in

which it remains a computer - then I think that that does cast doubt on the

validity of the Platonia theory.

*>For your vacation, you buy a ticket that allows you to be destructively
*

*>scanned and teleported to one thousand fabulous destinations around the
*

*>solar system. The machine also sends a copy of you to a receiving station
*

*>next door, on Earth (it's the rules). You enter the sending station, press
*

*>the red button, and a second later find yourself in slightly altered
*

*>surroundings. When you get out of the machine, you realise that you are
*

*>still on Earth. Disappointed, you buy another ticket on the spot and go
*

*>through the same procedure again, hoping for a better result. Again,
*

*>however, you walk out and see that you are still on Earth. This time, you
*

*>are angry. The probability that you finish up the stay-home copy twice is
*

*>less than one in one million! You suspect on this basis that the company
*

*>running the teleporter has cheated you, and did not send copies to the
*

*>holiday destinations at all.
*

Your vacation-company thought-experiment brings up interesting issues about

falsifiability. If I buy two tickets in a row, and I reappear on Earth both

times, I'm tempted to suspect that I've been cheated. On the other hand, I

know that the chances were 100% that this was going to happen to *some*

copy. So maybe I'm just that unlucky copy? Unfortunately, if you continue

to think in this way, you give up the idea of falsifiability completely. No

matter how many times you buy a ticket and reappear on Earth, you can

always argue that the chances were 100% that this would happen to some

copy. No amount of empirical data can ever convince you that the company is

cheating you. This is fine if you have some independent reason for trusting

the company with 100% confidence, but without such an independent reason,

you should suspect foul-play.

-- Kory

Received on Sun Apr 25 2004 - 05:52:05 PDT

Date: Sun, 25 Apr 2004 05:45:38 -0400

At 10:36 AM 4/24/04, Stathis Papaioannou wrote:

Not yet. We know that the bizarre, inconsistent worlds must exist if the

Platonia idea is correct, but we (or at least I) don't currently know how

likely they are. In Platonia, there are X number of possible-next-states

from my current state. (For simplicity's sake, lets even say that X is a

very very large finite number.) If a vast majority of these states show me

sitting in my chair typing, with my computer not turning into a kangaroo,

etc., then no, the fact that my world so far has not been bizarre and

inconsistent does *not* cast doubt on the validity of the Platonia theory.

In fact, if we can show logically, mathematically, or computationally (for

me these are all ultimately the same thing) that a vast majority of my

next-possible-states do in fact show me sitting in my chair typing, with

very few computers turning into kangaroos, this would be an extremely

strong reason to believe that the Platonia theory is correct, because it's

survived a rather stringent falsification test.

Note that the tests we need to perform - tests like "how many of my next

possible states show me still sitting in my chair? How many of my next

possible states show my computer turning into a kangaroo?" - are logical /

mathematical / computational ones, not empirical ones. We already have the

empirical data, which we call "the laws of physics". We need to know what

the Platonia theory actually predicts, and compare it to the empirical

data. For my part, I don't actually know what the Platonia theory predicts,

because I have no idea how to go about addressing the question

mathematically. Bruno Marchal says we need to create a better model of what

counts as a platonistic observer, and "interview it" about its relative

consistent extensions (what I've been calling "next-possible-states"), and

find out what regularities it would see. To me, that's just another

statement of the problem. I don't have a very good model of what counts as

a platonistic observer, and I don't know how to determine the structure of

its next-possible-states, etc.

If we make progress on this issue, and we come to the mathematical

conclusion that the probabilities we're looking for *don't* exist in

Platonia - that is, if we determine that (say) my next-possible-states in

which my computer turns into a kangaroo are just as common as those in

which it remains a computer - then I think that that does cast doubt on the

validity of the Platonia theory.

Your vacation-company thought-experiment brings up interesting issues about

falsifiability. If I buy two tickets in a row, and I reappear on Earth both

times, I'm tempted to suspect that I've been cheated. On the other hand, I

know that the chances were 100% that this was going to happen to *some*

copy. So maybe I'm just that unlucky copy? Unfortunately, if you continue

to think in this way, you give up the idea of falsifiability completely. No

matter how many times you buy a ticket and reappear on Earth, you can

always argue that the chances were 100% that this would happen to some

copy. No amount of empirical data can ever convince you that the company is

cheating you. This is fine if you have some independent reason for trusting

the company with 100% confidence, but without such an independent reason,

you should suspect foul-play.

-- Kory

Received on Sun Apr 25 2004 - 05:52:05 PDT

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