Bruno Marchal writes:

> >> Parfit is good. I stop to follow him when he insists that we are 
> >> token.
> >> I paraphrase myself sometimes by the slogan MANY TYPES NO TOKEN.
> >
> > Can you explain the disagreement with Parfit? My reading of chapter 99 
> > of
> > R & P is that a "token" is a particular instantiation of a person 
> > while a "type"
> > is the ensemble of related instantiations. "Mary Smith" is a type, 
> > "Mary Smith
> > coming out of replicator no. 978 at 11:05 AM" is a token.
> When I say "MANY TYPES NO TOKEN", I assume comp *and* the conclusion I 
> derive from it, that is the reversal between physics and "number 
> theoretical machine theory" (say). In particular I take from granted 
> that my next "observer moment" is somehow determined by two things: a 
> "proportion" of computational histories going through my actual 
> computational state, and the proportion of consistent extensions, which 
> are related to a "proportion" of similar computational histories.
> So with comp "Mary Smith coming out of a replicator no. 978 at 11:05 
> AM" is a type. It is the type of all (2^aleph_0) histories going 
> through that event (supposedly well 3-described).
>  From a third person point of view, if you are willing to say that the 
> natural numbers are token (I am neutral on that), then it would make 
> sense to see the nth step of an immaterial execution of a DU, (or an 
> enumeration of the true sigma_1 arithmetical sentences) as (immaterial) 
> tokens. But even in that case, there would be no sense to attribute 
> tokenness to "Mary Smith coming out of a replicator no. 978 at 11:05 
> AM", because there is no way to privilege one instantiation from 
> another. We must take them all, and they constitute highly undecidable 
> sets.

I think this might be a terminology issue. There may be many computations 
or processes in the multiverse implementing the OM "Mary Smith no. 978 at 
11:05 AM". From a third person POV it may be possible to point to a computer 
and say "that's MS 978 #1" and another computer and say "that's MS 978 #2", 
these being two instantiations of the one OM, but from a first person POV it is 
not possible to make such a distinction, otherwise they would be different 
I would further add that if the third person distinction leads to any 
with the two instantiations as separate entities then that also forces them to 
become distinct OM's since it changes their first person experience. It is 
really only an observer who will not interact with the separate instantiations, 
like a deistic god overseeing the universe, who can tell them apart. So someone 
who has a relationship with Mary Smith will at any one time have a relationship 
with a particular Mary Smith token, which might actually have multiple 
instantiations not distinguishable by either Mary Smith or the observer as 

I think it is the term "token" that is confusing. "OM" is less problematic.

> > It appears that in this terminology (actually due to Bernard Williams, 
> > not Parfit)
> > once generated a token remains the same token until there is another 
> > branching,
> > but my preference is to generalise the term and say that a token has 
> > only transient
> > existence, which then makes "token" equivalent to "observer moment".
> OK. I prefer.
> With comp it has to correspond to the third person Observer Moment (OM 
> hereafter).
> They are the true Sigma_1 sentences, or the accessible states by the UD.
> > This is
> > literally true, given that from moment to moment, even in the absence 
> > of teleportation
> > etc., the atoms in your body turn over such that after a certain time 
> > none of the
> > matter in your body is the "same", and before this time the fact that 
> > some of the
> > matter in your body is the "same" is accidental and makes no 
> > difference to your
> > conscious experience.
> Assuming bodies. I see the point.
> >
> > As to whether I am token or type: obviously, literally, 
> > I-who-write-this-now am a
> > token.
> This looks like the first person OM. It is different from the preceding 
> one.
> The 3-OM are enumerable, even recursively enumerable.
> The 1-OM  are enumerable but not recursively enumerable (for those who 
> have the Cutland, it is a simple consequence of Rice theorem).
> And the similarity classes of the 1-OM (= states plus its relative 
> proportion) has the power of the continuum.
> >  My present token is included in the set of related tokens in the 
> > past, future,
> > other branches of the multiverse, surreptitious emulations of my mind 
> > made by aliens,
> > and so on: the type. Note that the definition of a particular token 
> > (especially in my
> > generalised sense, fixed to a specific and unique position in the 
> > multiverse) can be
> > made completely unambiguous,
> How? With comp (with the multiverse = UD*) you have to bet on a level 
> of description of you, and then, even in the lucky case of a correct 
> bet, I still don't see how you will discover you present token, if only 
> because of the many undistinguishable computational histories going 
> through that state (which I recall you can only bet on).
> This was about your 3-OM token. The situation is even more difficult 
> for the 1-OM token, which is determined in the neighborhood of the 
> infinite.
> And frankly if you believe a recording can be conscious, don't forget 
> to look for the infinitely any emulation any recording before telling 
> me where is your 1-OM in UD*.

The 1-OM is completely unambiguous: I am having an experience now. I 
don't know how or where or on how many machines my mind is being 
implemented, but I certainly know that I am having an experience now. 
What is vague and arbitrary is to what set of related experiences my present 
experience belongs, i.e. what counts as "Stathis" or "the Stathis type".

> > while the definition of a type is necessarily vague and
> > fuzzy arround the edges. For example, if a being exists somewhere with 
> > 70% of
> > my memories and 30% of your memories, should he be included in my 
> > type, your type,
> > a new type, or some combination of these? It is only because we 
> > experience a linear
> > existence from birth to death, so that only a single token is extant 
> > at a time and there
> > is clear physical continuity from one token to the next, that we can 
> > ignore the distinction
> > between token and type and consider the definition of a particular 
> > type to be
> > unambiguous.
> I agree. But thought experiments involving self-duplication are here to 
> remind such distinctions. Like the superposition is contagious in the 
> quantum multiverse, with comp typeness is contagious: Mary Smith, being 
> digitally duplicable, is a type and when she leaves the replicator 978, 
> she does not instantiate in "Mary Smith coming out of a replicator no. 
> 978 at 11:05 AM", she just particularizes herself into the more 
> particular type of the "Mary Smith coming out of a replicator no. 978 
> at 11:05 AM". But there are many of such types, even not counting those 
> emulated by the "recordings" emulated in the UD* (or the sigma_1 true 
> sentences).

OK, but there is a difference in kind rather than in degree between the 
type "Mary Smith no.978 at 11:05 AM" and "Mary Smith": the former is precise 
and unambiguous from the first person POV, while the latter is not from either 
first or second person POV.

> > As for what matters in survival, that is a contingent fact of the way 
> > our brains have
> > evolved.
> We can bet that survival of (many pov) values is necessary in the long 
> term.


> >  It isn't as simple as saying that survival of type is what matters, 
> > except in the
> > abovementioned linear existence with which we are familiar. One 
> > concise way to put it
> > is that what matters in survival is that there should exist at least 
> > one token (or observer
> > moment, or instantiation) which has my present token's memories in its 
> > past. Moreover,
> > it is important that where several such tokens exist, as I may feel 
> > myself "becoming" any
> > one of them with equal probability, as many as possible should have 
> > good experiences.
> > This works for simple branchings, but it becomes complicated when we 
> > consider mergings
> > and partial memory loss. Another problem is tokens in parallel worlds: 
> > I could say I don't
> > survive if no future tokens exist who have my present memories,
> OK, but I really think that it is less misleading to reason on a block 
> reality (like UD*), instead of taking the risk to confuse first person 
> time (which cannot not exist) and third person time (which could not 
> exist)

Yes, present and future could be defined by linear time, or they could be 
defined in a block universe, or computations run backwards, in parallel, or 
in mixed up order: the subjective effect will be the same.

> >  even though other tokens
> > exist in the multiverse who branched off some time ago, but then that 
> > would be like saying
> > I don't survive if I experience any memory loss at all, for example 
> > due to medications like
> > midazolam. It could be that every second, tokens are finding 
> > themselves in hellish multiverse
> > branches where they suffer horribly then die, which is equivalent to 
> > suffering horribly then
> > having the memory of the experience erased.
> Hoping that is possible.

Perhaps this actually is happening all the time and is the explanation for the 
"white rabbit" problem. We are constantly finding ourselves in universes where 
bizarre and probably unpleasant things start happening but those univeses are 
unstable and represent dead ends, of which we are not aware in our present 
subjective timeline. It is a strange thought: if it could somehow be 
that every second of your life, you are branching out into hellish worlds with 
perhaps very high probability (i.e. your next OM is almost certain to be in one 
these worlds), would you worry? Or would you just think, I haven't worried all 
these years while it was happening, so why should I worry now?

Stathis Papaioannou
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