From: Void where inhibited (daniel.fabulich@yale.edu)
Date: Sat Nov 21 1998 - 21:58:58 MST
Ah, the ever returning question of identity.
Two objects which are identical down to the quantum level share a certain
sameness. However, they are two objects. Does the principle of Identity
of Indiscernables tell us when and how we can tell when TWO objects (2,
count em, TWO) are the "same?"
No, actually, it doesn't. The principle of Identity of Indiscernables is
making a statement about *physical states.* Specifically, that if we take
two indiscernable objects (which is to say that we take a PAIR of objects,
two of them!) and switch them, the state of the universe following this
switch is perfectly identical to the state of the universe before the
switch. I repeat, the state prior to the switch is identical in every way
to the state following the switch.
Now, of course, only objects which are extremely similar (that is,
indiscernable down to the quantum level) can satisfy the requirements for
this principle. And, since this principle is an "if or only if"
statement, we might be inclined to run it in reverse: if you could switch
two objects and get a physical state indiscernable from the original
state, then the objects must be identical.
But despite the fact that these two objects (dos, duo, not 1 or 3; four is
right out!) are identical, they are not the "same object." They are:
*two* *indiscernable* objects.
To say that two indiscernable objects are really the SAME object, we'd
have to imagine some metaphysical object off in Plato's heaven, an object
of which the two things we see are mere instantiations. Even then,
however, they'd still be *two* instantiations of one thing.
How does this relate to consciousness? Well, consciousness IS the one of
those things that exists only in Plato's heaven. Being a metaphysical
object, it obeys all kinds of rules and laws that we'll never know about
and that science can never truly understand, ya da ya da. Of course,
skepticism probably isn't what this debate needs right now. We know a
little about consciousness, don't we? So let's just assume that you've
got some and I've got some and that if either of us died at this moment,
the dead one wouldn't have any.
Now, let's try to remember why we started thinking about this question in
the first place. In fact, the question was essentially pragmatic/ethical:
If an identical copy of me existed, would it be OK if the copy died?
Would "I" continue living so long as one copy of me continues living?
Now, here, people have falsely applied Identity of Indiscernables to say
"Yes, definitely. If the I.o.I. principle is true, then the two copies
are the same person." Well, again, this requires us to assume that there
is a "person," a "consciousness" off in Plato's heaven, of which the two
copies are instances. We have two instances, obviously, but so long as
they're both instances of the same person, it should be fine if one of
them dies. The true form of you exists so long as one of your copies
exists.
Now, I'm going to make the big leap here. Many of you will disagree. But
here we go:
There is no true form of a person. There is no Plato's heaven.
OK, where does this leave us? This means that the two copies are two
identical people. Since it's obviously a bad idea for a person to die,
we'd better not kill either copy, right?
Well, not necessarily. It's a faulty ethical assumption to presume that
death is always a bad idea, particularly when the person dying doesn't
mind. (Here's the libertarian in me showing through. If you're into
deontology, you won't like this a bit.) While it seems inherently unwise
for a person to kill themselves, I think it takes an even bigger leap than
I just made to presume that it is universally morally wrong for them to do
so.
I personally see no reason to kill myself, and would strongly advocate
against any of you trying this at home. That being said, I can think of
reasons why a person might believe that their own interests would be best
served by their own deaths. Under those circumstances, and presuming that
they don't trample on other peoples' rights in the process, such people
can and should be allowed to risk or even sacrifice their own lives for
whatever reasons they see fit.
This brings me back to the copies. It seems not at all unreasonable that
the copies might be willing to die so that the other one would live. We
see this all the time in parents willing to give their own lives for their
children. Indeed, by a simple extension of evolutionary psychology, we
should expect that the copies would be at least as willing to die for one
another as two siblings might be, if not more so. I'd be inclined to
think that they'd be MUCH more willing to do so, since (at least for a
fraction of a second) they'd even satisfy the conditions for Identity of
Indiscernables: for a brief moment, they'd be identical *in every way*.
So I answer the question this way: If the copies don't mind dying so long
as one of the other copies still lives (or so long as another copy can be
made,) then it's fine for them to do so. If you make many such copies,
you'll have many people who place a low value on their lives individually
but great value on the permanence of at least one copy. Ethically
speaking, if it's fine with them, it should be fine with us.
You might be asking yourself "Now, that's all good and well, but should
*I* be willing to die so long as one of my copies still lives?" If
Plato's heaven doesn't exist, then this is a question which no one can
answer for you. I don't think I'd mind. You might. If so, then there's
no arguing with you. No one can tell you that you shouldn't mind, any
more than they can tell you that you shouldn't feel what you feel.
Flames welcome.
-Dan
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