From: gts (gts@optexinc.com)
Date: Thu Sep 05 2002 - 23:27:28 MDT
Dan,
>> Yes, and I've rejected both hypotheses:
>>
>> 1) That there is only a .999... probability that you are 23 is
>> sufficient grounds for withholding judgment about your age.
>> We can say that you are very likely to be 23 but we cannot say
>> you are in fact 23.
>
> That's not what I understood your position to be.
I was referring to my position with respect to the new modified version
of the age problem that we discussed in the previous exchange. In that
version I know a priori that you have a 99.99% probability of being (or
of proving) your age to be 23.
You'll recall that I offered this modification to make the age problem
comparable to the immortality problem. In both cases we now have
explicit knowledge that the object of our inquiry (you or the potential
immortal) has probability < 1 of having the given property in question
(of being 23 or of being immortal). Without this modification your age
problem is not comparable to the immortality problem, at least as I see
it. This is so because Eliezer's model specifies an actual probability
of living forever whereas your original age problem makes no such
specifications about the probability of you being 23.
>> Perhaps the real question here is why this statistical
>> argument, (that a high probability of being immortal should be
>> considered equivalent to immortality), is less than satisfying
>> to me and to at least one other person here who has indicated
>> a similar dissatisfaction to me in private email.
> *This* is exactly the question I was getting at.
Well good! I'm glad we (sorta') see the same problem. ;-)
>> In other words we need something more akin to a
>> mathematical proof. For example I can prove the truth or
>> falsehood of a statement about the exact rate of
>> acceleration of a falling object at time t with nothing
>> more than mathematics and the empirical observations of
>> physicists. Something similar should be possible in proving
>> the truth of falsehood of propositions about human immortality.
>
> I don't think this is the difference.
(First let me say, lest any of my old physics profs be watching :-),
that had I been paying closer attention to my own words then I would
have written about testing the truth value of a statement about the
velocity of a falling object at time t, as opposed to a statement about
its rate of acceleration at time t.)
> The example of the falling object is in the same vein. You
> can state the acceleration rate to within some margin of error;
> the same holds for the immortality argument (we can even directly
> bound the % chance of error).
If memory serves, the rate of acceleration of a falling object here on
earth is known to be 32 feet per second per second. The velocity at time
t can be calculated exactly, *in principle*, with no need for
probabilistic arguments or margins of error. I realize that in actual
practice there will be margins of error due to measurement limitations
and random or unmeasured effects from winds and geographical differences
in gravity and the like, but *in principle* the velocity at t can be
calculated exactly. This type of certainty about a given object is not
present in Eliezer's statistical argument, which is (I believe) the main
reason I find it unsatisfactory.
I want to know if the object has the property or not, and only rational
non-statistical arguments can give such certainty.
> In charity, *I* think the reason that you find probabilistic
> arguments for immortality especially troublesome, compared to
> probabilistic arguments in favor of my age, is that you think of
> immortality as being a special case of confidence, of certainty.
I don't think that's the reason I find the argument troublesome. Instead
of questioning that immortality is possible, we could instead question,
for example, whether women are capable of having 30 children in a
life-time. The arguments would all be the same. I would want to know if
*this* woman will have 30 children. Statistical arguments such as
Eliezer's would not offer an answer, even if 99.9999999... percent of
women in the population will have 30 children.
> Similarly, if you think that immortality MEANS 100% confidence in an
> infinite lifespan
I would not argue along those lines. I agree that a given person will
live forever or not live forever, regardless of anything he or I might
think about it.
> But, I challenge this definition altogether. Immortality,
> as exemption from death, doesn't mean 100% confidence in anything.
Right.
> Take an example: it makes logical sense to say that somebody
> could be 100% immortal by a mathematical proof and the
> laws of physics [ie an imaginary argument *much* stronger
> than the one given thus far], *but not realize
> this*. Perhaps, for example, nobody had ever told this
> person the proof.
Sure, that's entirely possible.
That "imaginary argument much stronger than the one given thus far" is
exactly the argument that I would like to see. I realize that given our
present state of knowledge such an argument is difficult or impossible
to construct, but that is nevertheless the kind of argument that we
should be seeking to construct if we are motivated in this area.
> The fact that this example even *makes sense* means that
> immortality is not a special case of certainty.
Again, I don't believe immortality is a special case of certainty.
> Of course, you could imagine immortality to be whatever you
> like, but I don't see how it would be informative or helpful
> to treat it as "certainty."
I don't treat it as certainty.
Immortality either is or is not achievable by person X. Statistical
observations about the population from which person X was drawn cannot
tell me if person X is or is not immortal. The only exceptions are the
special cases in which every person in the population is found to be
either mortal or immortal, but neither of those special cases are the
case we are considering.
-gts
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