Re: Questions on Russell's "Why Occam" paper

From: Patrick Leahy <>
Date: Thu, 9 Jun 2005 01:55:32 +0100 (BST)

[Russell Standish wrote]:

> The AP is a statement that observed reality must be consistent with
> the observer being part of that reality.

Famously, this can be interpreted as either a trivial tautology (Brandon
Carter's original intention, I think), or an almost-obviously false
principle of necessity (Barrow & Tipler's SAP). If you think there's a
mystery here it suggests you go for the necessity version, but given your
infinite ensemble the tautology would suffice perfectly well.

You also said:

>> >The observer _is_ the interpreter. There may well be more than one
>> >observer in the picture, but they'd better agree!
>> Why does this follow? <snip>
> It follows from the Anthropic Principle. If O_1 is consistent with its
> observed reality, and O_2 is consistent with its observed reality, and
> O_1 observes O_2 in its reality, then O_1 and O_2 must be consistent
> with each other (at least with respect to their observed realities).

Ah. Just to be sure, do you mean that the string the observer "attaches
meaning to" is the one which describes the very same observer? This seems
to be implied by your comment above; but you don't say it or clearly
imply it in your paper.

Then you are implying that the observer can, in a finite time, read and
attach meaning to a full (space-time) description of itself, including the
act of reading this description and so on recursively.

Which is impossible, of course.

You also said:

> I'm not entirely sure I distinguish your difference between "external
> world" and "internal representation". We're talking about observations
> here, not models.

I'm sure you can distinguish *my* mental representation of the world from
your own. Hence if we share a world, and you can't distinguish between
that world and your internal representation, then you are not granting
equal status to other observers such as me.

You also said (quoting me):

>> My problem is that you are trying to make your observers work at two
>> different levels: as structures within the universes generated
>> (somehow!) by your bitstrings, but also as an interpretive principle
>> for producing meaning by operating *on* the bitstrings. It's a bit
>> like claiming that PCs are built by "The Sims".
> Yes it is a bit like that. Obviously, the Anthropic Principle (or its
> equivalent) does not work with "The Sims".

Actually I don't see why not. The existence of The Sims implies a universe
compatible with the existence of Sims. But granting this is not so for the
sake of the argument, presumably the AP *will* apply to the Sims Mark VII
which will be fully self-aware artificial intelligences. But it will still
be absurd to claim that the Sims are responsible for construction of PCs
(assuming they are not connected to robot arms etc, for which no analogs
exist in your theory). Let alone for them to construct the actual PC on
which they are running, as apparently implied by your last message... even
robot arms wouldn't help there.

Paddy Leahy

Dr J. P. Leahy, University of Manchester,
Jodrell Bank Observatory, School of Physics & Astronomy,
Macclesfield, Cheshire SK11 9DL, UK
Tel - +44 1477 572636, Fax - +44 1477 571618
Received on Wed Jun 08 2005 - 21:11:25 PDT

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