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Re: New version of URI Declarations [Usage scenarios]

From: John Cowan <cowan@ccil.org>
Date: Fri, 14 Mar 2008 11:06:12 -0400
To: Pat Hayes <phayes@ihmc.us>
Cc: "Booth, David (HP Software - Boston)" <dbooth@hp.com>, "www-tag@w3.org" <www-tag@w3.org>
Message-ID: <20080314150612.GD30174@mercury.ccil.org>

Pat Hayes scripsit:

> Well, this illustrates the problem, seems to me. Suppose I accept 
> your claim that your URI denotes the moon, so that when I use it I am 
> also referring to the same moon. But I want to point out that you 
> said something false about the moon. Under your proposal, this is 
> impossible. I can't say that, because by calling these assertions a 
> 'declaration', they have been removed from the domain of discussion. 

So they have, but that's unavoidable.  If we take the predicates "is a
natural body", "orbits the Earth", and one more that I can't formulate
exactly but is meant to exclude captured meteoroids if any there be,
then these *define* the moon.  If you contradict any of them, you are not
talking about the moon any more.  (Another basis system could be given,
such "occupied point P at time T" for appropriate choices of space and
time scales; it matters not.)

Note that none of these are essential properties in the Kripkean sense
I was using before; essential properties are not necessary as long as we
confine ourselves to the actual world and don't worry about contrafactual
worlds.

However, once the moon is properly defined (= distinguished from all
other objects to the extent possible or required), I can then make any
number of assertions about it, any of which you may contradict, of course.

> Why should it be that by using a name correctly, given your 
> intentions for using it, that I must therefore agree with everything 
> you say about it? 

Not everything, only the assertions in the declaration (of identity).

-- 
What has four pairs of pants, lives             John Cowan
in Philadelphia, and it never rains             http://www.ccil.org/~cowan
but it pours?                                   cowan@ccil.org
        --Rufus T. Firefly
Received on Friday, 14 March 2008 15:06:54 GMT

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