Re: Modal Realism vs. MWI

From: Russell Standish <>
Date: Tue, 8 Oct 2002 16:18:38 +1000 (EST)

Tim May wrote:
> However, I take your point that full Lewis-Stalnaker-D. Lewis modal
> realism is "more disjoint" than the "less disjoint" (initial
> interference of branching worlds) MWI. In terms of topology, one might
> say full modal realism is the discrete (perhaps Zariski) topology,
> while MWI has more notions of closeness, overlap, etc. (I think this
> could be worked out, but I haven't.)
> Certainly after a time interval where decoherence occurs, the
> interaction between macroscopically different worlds is essentially
> zero.
> So, I will amend my earlier statement to read: "After the very early,
> entangled period, MWI looks, then, like just another variant of "modal
> realism." To wit, there IS a universe in which unicorns exist, and
> another in which Germany won the Second World War, but these universes
> are forever and completely out of touch with us."
> And since the time of entanglement/coherence is small for most systems,
> most worlds in MWI are as "far apart" as modal realism worlds are.
> (Digression: I wonder what kind of work has been done on _evolution_ in
> topology, e.g., the transition of systems from "overlapping open sets"
> to the "discrete" topology? Looks like nucleation and growth out of a
> continuous medium, or formation of tree structures, perhaps.)

It would appear to me that the modal realism world is a necessity for
consciousness, but that the Multiverse, with its coherence structure
is approximately good enough to allow consciousness to operate.

Having said that, linear interference possibilities appear to be
allowed anyway in the modal realism type model (that seems to be the
import of my "Why Occam's razor" paper.


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Received on Tue Oct 08 2002 - 02:20:26 PDT

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