X-Message-Number: 9217
Date: Fri, 27 Feb 1998 08:49:51 -0800
From: "Joseph J. Strout" <>
Subject: Re: identity & survival

Robert Ettinger writes:

>Joe Strout's comments on memory and survival or identity (#9203) seem to
>reflect the "quantitative" criterion. Sliding past questions of continuity,
>you have survived, with respect to some particular characteristic, to the
>extent that the characteristic persists (or is renewed) unchanged.

Yes, that's it in a nutshell, though I prefer the descriptive "fuzzy-logic"
to "quantitative" (since, ironically enough, fuzzy logic is a well-defined
concept, just like Boolean logic).

>...the whole
>issue concerns the APPROPRIATE importance to be assigned to various types and
>degrees of change.

Very true.  I believe that your mental structure, and in particular your
memories, are most important to personal identity.  (And as Thomas pointed
out yesterday, it is not the historical accuracy of these memories that
really matters; it is their content.)  This view clears up a number of
"difficult" scenarios...

>As a far-fetched
>example, suppose I am reconstituted 200 years from now--not as I am now or as
>I will be on my deathbed, not as I was at an earlier age, but as I WOULD HAVE
>BECOME 200 years from now, if the antiaging breakthroughs had arrived in time.

It's easy to imagine impossible things and say they pose a problem.  How
could this be possible?  If you really existed, you would have 200 years'
worth of experience, learning, memories of family vacations, contracts and
obligations, etc.  You could not be reconstituted de novo with all these
memories in place, because those things never happened; there were no such
contracts, no family vacations, no learning.  If your cruel re-creator
chose to make up these experiences and somehow plant them in your brain,
you'd quickly discover that nobody else remembers the things you do -- and
so again, it would NOT be the same as if you had 200 years of real
experience.

But, nonetheless, you would still be Robert Ettinger, at least partly the
same person as you were on your deathbed.  Just a person on whom a cruel
joke has been played.  This is because your first century of experience
will still be there, making up a large part of who you are.

>Or suppose that, in a galaxy far, far away, in a time long, long ago, there
>was a planet almost exactly like ours, and a person almost exactly like me,
>who through happenstance lived considerably longer than I am destined to live
>before freezing. Was that past/future person me?

This is even less possible than the first scenario -- again, it seems we're
stretching to imagine impossible situations, then seeing how they make us
uncomfortable.  (Of course, I've been known to do the same thing -- e.g.,
suppose aliens take us apart every night while we sleep, then put us back
together?)

But suppose this alternate-Earth could happen -- perhaps in a parallel
universe or some such.  Perhaps a parallel universe that diverged from ours
only yesterday, so that up till then, everything happened exactly the same,
and you and your duplicate were exactly the same person.  Then if one of
you is hit by a bus tomorrow, then yes, in another universe, you survive --
though that won't make much difference in the universe containing the bus.

>Should I therefore have less reason to avoid death?

If there are alternate universes constantly diverging, then each has its
own timeline, and we must decide which timeline(s) is/are important with
respect to survival.  Personally, I consider there to be only one timeline,
and so I'm interested in seeing that I survive in this one, not some
alternate one.

>Well, suppose you die but have a grandchild who is very similar to you, not
>only genetically but also in upbringing, personality, etc.

We could even better suppose you have an identical twin, raised in the same
home, at the same time, etc.  My father-in-law and his brother are such a
pair.

>The grandchild's memories would not be yours in detail, but they might
>be very similar in their psychological quality and effect on personality.

But they would not be the same memories at all.  Not a single one would be
the same, even between identical twins.  They will always differ at least
by point of view; Don sees Ron from his vantage point, while Ron sees Don
-- and though they may look enough alike to fool their teachers, I
guarantee that *they* know the difference!

To the extent that personality is partly genetic, twins or clones will be a
very little bit the same person.  And to the extent that it's partly
cultural, two people raised in the same culture will be a little bit the
same person.  But even identical twins raised in the same household are
only a *very* little bit the same person, since they have had different
experiences since before they were born.

>Maybe, by some calculations, that grandchild would be 60% you.

To me, that is simply a grossly incorrect calculation.  It's hard to put
hard numbers on fuzzy concepts, but you might try by saying that 60%
identity means you would answer 60% of randomly-selected questions in
exactly the same way.  And questions such as "what did you get for your
tenth birthday" and "who was your first boy/girlfriend" are fair game.  Two
people with NONE of the same memories could hardly be the same person at
all.

>If you eventually have 1,000 descendants, each on average 1% you, have
>you survived 10 times over?

No, you have not survived at all (or hardly at all), because there is not
in the future any person who is mostly the same person you are today.
Survival is not additive!

>Joe also says that "most answers to the personal identity question fail on

>tests of logic or self-consistency, or are not consistent with common usage=D6"
>I think ALL proposed answers (that I have seen) fail on one or more of these
>tests.

Well, it's been several years since I've been arguing this fuzzy-memory
theory, and nobody has yet been able to propose an objection that sticks,
as far as I can tell.  The biggest challenge to it is that it allows
duplication (i.e., a person can be duplicated, resulting in two of the same
person), which strikes us as odd.  But I think this is only odd because it
has never happened before.


Best regards,
-- Joe

,------------------------------------------------------------------.
|    Joseph J. Strout           Department of Neuroscience, UCSD   |
|               http://www-acs.ucsd.edu/~jstrout/  |
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