W3C home > Mailing lists > Public > uri@w3.org > April 2003

Re: resources, stuffs and individuation

From: John Cowan <cowan@mercury.ccil.org>
Date: Mon, 21 Apr 2003 18:33:36 -0400
To: pat hayes <phayes@ai.uwf.edu>
Cc: uri@w3c.org
Message-ID: <20030421223335.GL29719@ccil.org>

pat hayes scripsit:

> Thus, for example, each of the sodium atoms in my body has an 
> identity - it is identical to itself - in the first sense, even 
> though none of them has an identity in the second sense, since we 
> have no agreed-on scheme for referring to individual atoms (and there 
> are too many of them to keep track of, in any case).

This is peripheral to your point, but quantum mechanics tells us that
atoms are truly Leibnizian indiscernibles -- there is not only no way
to label all the sodium atoms in your body, but there is not even any
sense in which they can be individuated from one another.

(By "atoms" I mean only what physicists call atoms, not Leibnizian atoms.)

> First, I would suggest that the best road for the WG to take on 
> issues like these would be to be as agnostic as you feel you possibly 
> can be about the exact nature of 'resources'. 


> Second, it is important for almost all reasoning engines that the 
> general picture, of how URIrefs relate to whatever it is that they 
> refer to, should also allow for the existence of similar things which 
> are not referred to. That is, please do not say anything which 
> restricts the universe of discourse to include only those things that 
> have a URI or URI reference assigned to them (in whatever sense of 
> 'assigned' is appropriate.)  The reason for this request is that such 
> a restriction effectively makes it impossible to use quantifier 
> reasoning - that is, all kinds of formalized reasoning invented since 
> about 1880, including most reasoning software - over the set of 
> resources, so defined. The alternative logics that would be required 
> (those with a "substitution interpretation" of the quantifiers) have 
> been fully analysed and are known to be inadequate. This would be a 
> crippling decision.

I think you underestimate the power of substitutional quantification,
unnatural as it seems, to work in the Real World, an essentially finite
place.  Objectual quantification is clearly neater in a formal sense,
but provokes intractable computational difficulties.

John Cowan  jcowan@reutershealth.com  www.reutershealth.com  www.ccil.org/~cowan
"It's the old, old story.  Droid meets droid.  Droid becomes chameleon. 
Droid loses chameleon, chameleon becomes blob, droid gets blob back
again.  It's a classic tale." (Kryten, Red Dwarf)
Received on Monday, 21 April 2003 18:33:36 UTC

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