Re: Quantum accident survivor

From: Eric Cavalcanti <>
Date: Wed, 5 Nov 2003 11:08:56 -0200


I disagreed with some points in your argumentation...

----- Original Message -----
From: "David Barrett-Lennard" <>

> I'm trying to define "identity"...
> Let's write x~y if SAS's x and y (possibly in different universes) have
> the same identity.

You did not yet 'define' identity. You just proposed a relation between
two entities which is supposed to mean that these two entities have the
same 'identity'.

> I propose that this relation must be reflexive,
> symmetric and transitive.

This is a proposal which seems self-evident, but let us keep in mind that
we have no reason to propose it yet, since we don't even know what
'identity' means. I believe, in fact, that this relation '~' is NOT
Let me try to argue why later.

> This neatly partitions all SAS's into
> equivalence classes, and we have no ambiguity working out whether any
> two SAS's across the multi-verse have the same identity.
> Consider an SAS x that splits into x1, x2 (in child universes under
> MWI). We assume x~x1 and x~x2. By symmetry and transitivity we deduce
> x1~x2. So this definition of identity is maintained across independent
> child universes.

This is where the '~' relation shows that it cannot be transitive. I don't
know what your definition of identity is, but in other posts I have
argued that I am not the copies of me in other universes. Therefore,
since you have come to the conclusion that I am, it must be the case
that your assumption of the transitivity of '~' is wrong. To support your
definition of '~', you must give a better reason to believe that you are
the copies of yourself in other worlds. Just defining an arbitrary '~'
relation does not do the job.

In fact, I believe we should define another relation of personal identity,
which is NOT symmetric. I shall use the notation '<' meaning
that if x<y, x is a former state of y. 'x' is unambiguously defined by
following "down" the multiverse branching 'tree'. But we cannot define
the '>' relation, i.e., the relation by which y>x would mean that y is a
continuation of x 'uptree'. Since there are multiple choices for the next
state of x, it cannot be told in advance what the next subjective moment
will be.

So you can say that x<x1 and x<x2, but it does not follow that x1<x2 OR
x2<x1. And since, by my definition, personal identity can be determined
only by the relation '<', x1 does not have the same 'identity' of x2.

> This is at odds with the following concept of identity...
> > I am, for all practical purposes, one
> > and only one specific configuration of atoms in a specific
> > universe. I could never say that ' I ' is ALL the copies, since I
> > NEVER experience what the other copies experience
> It seems necessary to distinguish between a definition of identity and
> the set of memories within an SAS at a given moment.
> Is it possible that over long periods of time, the environment can
> affect an SAS to such an extent that SAS's in different universe that
> are suppose to have the same identity actually have very little in
> common?
> What happens if we "splice" two SAS's (including their memories)?
> It seems to me that the concept of identity is not fundamental to
> physics. It's useful for classification purposes as long as one doesn't
> stretch it too far and expose its lack of precision.

Maybe it is not fundamental to physics, but it surely is fundamental to
us, since that may be the difference between immortality or otherwise.
Even more importantly, it is the basis for all our daily decisions.
It is not merely a classification purpose. When you decide not to spend
your money on the lottery, you don't think that doing so is good,
because you will be increasing the number of 'yous' who are
rich elsewhere. You don't care for the other 'yous' because you truly
believe that the probability that you will just lose yor money is too high.
And if you don't care for the other 'yous' they are not really 'you', they
are other entities.

> This reminds me of the problem of defining the word "species". Although
> a useful concept for zoologists it is not well defined. For example
> there are cases where (animals in region) A can mate with B, B can mate
> with C, but A can't mate with C.

Although you can safely ignore those classifications when relating to
you cannot deny that defining your identity is too easy. Cut your finger
and you will know who is feeling the pain.

Received on Mon Nov 10 2003 - 08:09:35 PST

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