Stephen Paul King writes:
If we are to be strictly rational and consistent, it
is simplest to go to the extreme of saying that *none*
of the instantiations of an individual are actually the
"same" person, which is another way of saying that each
observer moment exists only transiently. This would mean
that we only live for a moment, to be replaced by a copy
who only thinks he has a past and a future.
Exactly what is the definition of "rational" here? Is it the same as my
implied "sane", e.g. not schitzophrenic?
Mike Perry, in his book "Forever For All" develops these
from the idea of "day-persons", i.e., the idea that you
are not the same person from day to day. But that's
certainly not a satisfactory way of extending our usual
notions into these bizarre realms; you and I want to live
next week because we believe that we are the same persons
we'll be then. And the idea that we *are* fuzzy sets in
person space permits this.
DOes Mike Perry elaborate on how anyone can know for sure that "they
are not the same person from day to day". What does he define "same" to be?
The point is that it is very difficult to pin down what is and is not "the
same person", especially in the unusual situations discussed on this list,
such as duplication, teleportation, mind uploading etc., but also in
everyday life. For example, human brains are constantly disintegrating and
being repaired with externally supplied matter, such that you have a
completely "new" brain every couple of months. Along with physical changes
come mental changes; we think that we retain memories over time, but even
without any brain pathology, our memories of past events probably change at
least as much over time as our physical bodies do. We cope with these
changes by saying that a person is "the same" if there is physical and
mental continuity over time, but it is not difficult to come up with
examples that thwart this criterion: for example, a person who has a head
injury, is in a coma for years, then wakes up with complete amnesia re his
past, along with a delusion that he is the Messiah, along with appropriate
false memories of an alternative and internally consistent life. That isn't
too far from what actually happens to thousands of people every day, and it
is as nothing compared to the sorts of mind manipulations that technology
could make possible in the future.
A standard example in the philosophy of identity is the Ship of Theseus,
which is kept in Athens as a museum piece (in legend, not in reality). Over
time, bits of the ship rot and are replaced. After many years, it could be
that only a small proportion of the ship is "original". Should it still be
called "the Ship of Theseus" if none of the matter in the ship was present
when Theseus sailed in it? What about if only one plank of wood has been
replaced? What if all the original material is all there, but the ship is
destroyed in a storm and is rebuilt from memory in a different configuration
to the original one?
There is a way to avoid arguments and ambiguity when referring to the ship:
aknowledge that the decision whether to apply the name "Ship of Theseus" is
ultimately arbitrary when the entity in question is changing over time, and
rather than trying to define, describe. That is, describe what it looks like
and of what material it is comprised at a particular point in its history.
Applying the same method to personal identity, we can avoid ambiguity by
describing the mental properties of the person in question at a specific
time: that is, the observer moments. We aknowledge that how the OM's are
arranged to give the first person impression of an individual persisting
through time, although it can be made clear and unequivocal in many cases,
is shown by consideration of examples as above to be ultimately arbitrary.
Now, what I meant in saying that we die every moment and are replaced by a
copy is that each OM is transient, and the successor OM, although usually
dependent on the same process as its predecessor (i.e. brain activity), is
not necessarily so dependent, and could arise from anywhere else in the
multiverse, or indeed never arise at all (which of course would mean real
death - no more OM's ever). I dicuss this more in my post to the list about
two weeks ago, "death".
The final point I wish to make is that if in fact someone came to your bed
every night, killed you in your sleep, then put an exact copy in your place,
there would be no way you could tell from introspection that anything
unusual had happened.
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