On Thu, Jan 12, 2006 at 11:12:13PM -0500, Benjamin Udell wrote:
> Russell, list,
> > Tegmark's 4 level "Multiverse" (actually the Multiverse is only one of the 
> > levels) does not really have viewpoints at each level.
> > In my book, which largely follows the tradition of this list, there is 3 
> > viewpoints identified: 1st person, 1st person plural and 3rd person.
> > The 3rd person corresponds to the bird viewpoint of the Multiverse, or 
> > Tegmark Level 3 'verse. Calling it a viewpoint is a stretch of the language 
> > since necessarily observers must be embedded in the Multiverse.
> Where does Tegmark say that the Multiverse is only one of the levels? Which 
> one?

"Multiverse" was coined by David Deutsch to refer to the many worlds
of MWI. This corresponds to Tegmark's level 3 parallel universe. I
follow this terminology, as do many others on this list. We also tend
to use the terms "Plenitude" or "Platonia" to refer to his Level 4
parallel universe. The other levels have not been "christened" so to speak.

Tegmark uses multiverse to refer to any type of parallel universe -
which I think contradicts usual usage.

> What is meant by "viewpoint"? Tegmark's elementary description of the four 
> levels sounds like the outline of four viewpoints, with "frog" and "bird" 
> marking the extremes of a four-step set of gradations. Level IV is associated 
> with "pure" maths. Level III is associated with alternatives among cases, 
> which marks it as associated with maths of logic, information, probability, 
> etc., despite what Tegmark says about logic's being the most general and 
> underlying thing in maths. Level III is more "abstract" than Level II and 
> actualizes alternate outcomes across quantum branchings, while Level II 
> actualizes alternate outcomes in various times and places along a single 
> branch, so that the two levels come out the same in their features. Level II 
> seems associable with statistical theory, some areas of information theory, 
> and some other fields deal in a general way with gathering data from various 
> actual places and times and drawing ampliatively-inductive conclusions from 
> parts, samples, etc., to totalities. Level I, with its possibly idiosyncratic 
> constants, initial conditions, historical dependencies, seems associable with 
> physical, chemical, life sciences and human & social studies. So those seem 
> four viewpoints with distinctive content and associations, though not the 
> kind of content which the idea of viewpoint seems to have received on the 
> everything list, which is decidedly not to say that there's anything wrong 
> with the kind of content given on the everything list to the idea of 
> viewpoint.
> Is it Tegmark's view, that the bird's eye view is associated particularly 
> with Level III, or does it depend on ideas as developed on the everything 
> list? Why wouldn't a view be associated with Level IV as well? (I thought 
> that, at least in Tegmark's view, the bird's eye view _was_ Level IV).

The term bird/frog viewpoint is Tegmark's, which he used in his 1998
paper. I can well imagine applying to his 2003 multilevel scheme.

The association of 3rd person viewpoint (not bird viewpoint) with the
Multiverse is mine, and is justified on the basis that all observers
must be embedded in quantum mechanical many worlds structure. This
result is derived by assuming a level 4 plenitude, and is given in my
2004 paper "Why Occams Razor". Bruno's work also seems to point to a
similar conclusion.

The particular Plenitude I assume (ensemble of all bitstrings) is
actually a completely uninteresting place to have a view of (it has
precisely zero informational complexity).

I do not see any particular arguments suggesting that observers must
be embedded in a universe described by string theory (which would move
the 3rd person viewpoint to level 2) or embedded in just this universe
(moved to level 1), but I would not rule it out a priori.

> > Both of the 1st person viewpoints correspond to the frog viewpoint, the 
> > difference being the 1st person plural is an objective viewpoint - all 
> > things in the 1pp vpt will be agreed upon by 2 or more observers, whereas 
> > the 1p vpt is subjective, containing items such as quantum immortality that 
> > are _necessarily_ subjective.
> The idea of quantum immortality doesn't seem like something that you could 
> call an "experience." If you found yourself alive even after what seemed an 
> unlikely long period of time, after a series of periodic extraordinary 
> escapes, any other observers would agree that you're still alive -- in other 
> words, you'd still be alive from the 1pp vpt. Only in the case where _no 
> records_ remain of your much earlier existence, nothing but your personal 
> memory of it, would quantum immortality seem possibly like an experience, an 
> "especially" subjective one. The quantum immortality idea seems like, not an 
> experience, but an idea requiring one's intellectually adopting some sort of 
> 3rd-person view.

I never used the word experience. Where did that come from? I seemed
to have avoided a particular word above, but I would say "knowledge"
is probably the most relevant. There are things one can know as a 1st
person, that are unknowable as a 1st person plural. I know I am
conscious. I don't know that you are conscious, but nevertheless
assume it. Conciousness is therefore 1st person, but not 1st person plural.

> Nevertheless, I've liked the idea of distinguishing an inclusive 1st-&-2nd 
> person "we," both addressor and addressee, from an exclusive 1st person 
> addressor-only, so I'm glad to see it pop up in this context.

I think we can credit Bruno with this distinction :)

> Best, Ben Udell

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