From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rutgers!att!news.cs.indiana.edu!bronze!chalmers Tue Mar 24 09:58:12 EST 1992
Article 4681 of comp.ai.philosophy:
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>From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Newsgroups: sci.philosophy.tech,comp.ai.philosophy
Subject: Re: A rock implements every FSA
Message-ID: <1992Mar24.051654.18747@bronze.ucs.indiana.edu>
Date: 24 Mar 92 05:16:54 GMT
References: <92Mar23.003224est.14362@neat.cs.toronto.edu> <1992Mar24.025128.9379@bronze.ucs.indiana.edu> <1992Mar24.042009.12510@organpipe.uug.arizona.edu>
Organization: Indiana University
Lines: 33

In article <1992Mar24.042009.12510@organpipe.uug.arizona.edu> bill@NSMA.AriZonA.EdU (Bill Skaggs) writes:

>  This is not really an original point -- Putnam says the same
>thing, I think -- but bringing counterfactuals into the
>picture only muddies it.  The problem, as Hofstadter very
>adroitly shows in "G\"odel, Escher, Bach" and "Metamagical
>Themas", is that making the condition (the "If not X" part)
>of a counterfactual true requires changing some aspect of
>the world, but it is often not obvious what aspect or aspects
>to change.  As Hofstadter puts it, it is not obvious which
>things are "slippable" and which are not.

It's not clear who you're responding to, but if it's me (presumably
my argument about counterfactuals), then:

1.  Putnam's point about counterfactuals concerns a very different
matter, as I pointed out a few days ago.

2.  The counterfactuals that I require the system to satisfy are
entirely well-defined.  They are of the form "if the system is in
state S1, and input I is received, then it will transit into state
S2".  This must hold for any physical state of the system that
falls under S1, and any physical input that falls under I.  There's
none of the looseness or underspecification that one gets with some
counterfactuals (e.g. the well-known "if Bizet and Verdi were
compatriots, then..."?  Bizet would be Italian?  Verdi would be
French?).  The implicit universal quantifier removes the need to
rely on such notions as slippability or closeness of possible worlds.

-- 
Dave Chalmers                            (dave@cogsci.indiana.edu)      
Center for Research on Concepts and Cognition, Indiana University.
"It is not the least charm of a theory that it is refutable."


