🚀 go-pugleaf

In article <7668@skye.ed.ac.uk> jeff@aiai.ed.ac.uk (Jeff Dalton) writes:
>In article <1992Sep17.154637.9156@guinness.idbsu.edu> holmes@opal.idbsu.edu (Randall Holmes) writes:

>It's important not to forget that David Chalmers is talking about logical
>possibility and not physical possibility.  Something might be logically
>possible even if physically possible.  Of course, not everyone will
>accept that logical possibility is an interesting notion.

That's sort of right, but I'm not happy with "physical possibility".
In general I'm happier calling the other major possibility class
"empirical possibility", or "nomic possibility" -- i.e. possibility
subject to the laws of nature.  Calling it "physical possibility"
buys into the assumption that the only laws of nature are physical
laws.  (The zombie is almost certainly nomically (empirically)
impossible, but it's obviously physically possible if it's logically
possible -- it's physically identical to me, so it can't violate
any laws of physics!)

In considering the relevance of the possibility of zombies for the
truth of physicalism, logical possibility rather than nomic
possibility is obviously the relevant notion.  I'm sure Mr. Holmes
is aware of this.

>Not so.  When two things are actually the same it can still be
>logically possible for them to be different.  Not always, though.
>You have to figure out which case you're in.  But you don't always
>have to know two things are actually different to know that it's
>logically possible for them to be different.

Not quite.  On the standard line, two things that are identical
are necessarily identical: how could something be other than
itself?  Take a look at Kripke's _Naming and Necessity_, for
instance.  However, what can be the case is that two *descriptions*
that pick out the same thing in the real world pick out two
different things in other 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."