RE: many worlds theory of immortality

From: Jonathan Colvin <>
Date: Fri, 15 Apr 2005 16:22:04 -0700

>Jonathan Colvin writes:
>> I didn't say that it *was* logically impossible for such a world to
>> exist; I said that it *might* be that such a world is logically
>> impossible. Just because we can talk about such a world does
>not mean
>> that it is logically possible.
>Hal wrote: It's important to understand that logical possibility is not a
>constraint on worlds as such; it is a constraint on our
>understanding of worlds.
>It's not like we could go to God and say, "God, please
>implement this world"; and God takes a look at the spec, and
>answers, in a deep, sorrowful voice, "No, I'm sorry, I can't
>implement this world, it's not logically possible. Go back
>and try again." And we say, "Okay, sorry, God, we'll try
>harder next time."
>If we think of computer programs as implementing worlds, all
>programs exist and are instantiated. It's not that some
>programs may be logically impossible and the universal TM
>refuses to run them.

Agreed. But some *worlds* we can imagine may be logically impossible
(inconsistent), may they not? I can imagine (or talk about) a world where
entity A has property X and property Y, but it may be logically impossible
for any existing entity A to simultaneously have property X and Y. For
example, it seems that it would be inconsistent for there to exist a world
where simultaneously I am omniscinent and I consist of a single elctron.
Such a world seems inconsistent (not logically possible). Such a world may
not appear in the set of worlds generated by all instantiated programs.

>Where logical possibility arises is in our understanding of worlds.
>The mere concept of a world where 2+2=5, for example,
>represents an error of understanding. What 2+2 equals is not
>a property of a world!
>It is incoherent to speak of a world where 2+2 equals anything
>specific, whether 4 or 5.
>We don't live in a world where 2+2=4. That mathematical fact
>has no bearing whatsoever on the existence of our world.

As a Platonist, I would disagree. In *all* possible worlds, 2+2=4. So we do
live in a world where 2+2=4.

> We
>live in a world with certain laws of physics: conservation of
>energy, quantum theory, Einsteinian gravitation. We may use
>mathematics to help us understand these laws, but the truths
>of mathematics are not contingent on anything about our world
>or any world.

Sure; it is the other way round: our world is contingent on the truths of

>If a world is logically impossible, the problem is always in
>our description and understanding of the world. Worlds
>themselves exist (given the AUH) independently of our
>understanding of them. Logical and mathematical consistency
>are not properties of worlds, they are properties of our descriptions.

Yes; but this is begging the question as to how we decide whether any
description we come up with corresponds to a logically possible world. Or
are you saying that any description necessarily corresponds with a possible
world? Is there a world where A AND ~A?

Jonathan Colvin
Received on Fri Apr 15 2005 - 19:25:29 PDT

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