W3C home > Mailing lists > Public > www-tag@w3.org > March 2008

Re: New version of URI Declarations [Usage scenarios]

From: John Cowan <cowan@ccil.org>
Date: Fri, 14 Mar 2008 12:23:08 -0400
To: Pat Hayes <phayes@ihmc.us>
Cc: John Cowan <cowan@ccil.org>, "Booth, David (HP Software - Boston)" <dbooth@hp.com>, "www-tag@w3.org" <www-tag@w3.org>
Message-ID: <20080314162308.GF30174@mercury.ccil.org>

Pat Hayes scripsit:

> Of course its not unavoidable. That is merely a consequence of the 
> mistaken idea that fixing a bunch of assertions is the same as fixing 
> a referent. This idea is wrong. They aren't the same, and to assume 
> they are gets one into a host of muddles, just like this one.

I don't assert that they're the same, simply that fixing a bunch of
well-chosen assertions serves to fix a referent.  There are undoubtedly
other ways to do it, like Kripke's chain of persons leading back to an
original baptizer, which I've discussed earlier.  Kripke shows that you
can get into trouble with the cluster-of-assertions model, but not that
it is useless for all purposes.

(We are told that the Irish, soon after the introduction of Christianity,
continued to feel that the binding quality of an oath worked better if
the Old Gods were gotten into it somehow, even if they could no longer
be named, so they would use formulae like "I swear by what my forefathers
swore by.")

> There is some evidence that there is a second moon, in fact, in a 
> very elliptical orbit.

Surely if so then it is captured.

> Um... yes, necessary properties aren't much use, 

In fact they can be just as good a basis as contingent properties (if
no better), and *are* better in the sense that they hold across all
possible worlds.  You seem to think for some reason that a property
cannot be both necessary and sufficiently narrow.  I still hold that
my DNA (given than I am not a twin) characterizes me both uniquely and
necessarily; it could have been the case (as it was not) that my parents
had some child with different DNA, but that child would not be *me*
(though it might have had my name) but someone else.

> You are ignoring the central point. What if your 'defining' 
> assertions are wrong, or contain a flaw of some kind? Does this 
> change the reference (so they are not in fact wrong at all, just 
> talking about something else) or is it a factual error? 

The former.  This encourages you to choose them carefully, and if other
people choose them poorly, to disregard their names.

> How can we even discuss this matter, if we cannot even contemplate
> the possibility that an assertion in a declaration might be false?

By saying that the resulting definition is not useful.

> OK, then it follows that YOU are using your own name incorrectly, 
> right?

Sorry, this is unintelligible to me.

> This does not seem to fit well with the notion that an owner 
> of a URI has control over what it denotes.

Control, yes; but if the URI is to be useful, it cannot be merely "The
URI u means what I want it to mean, changeable at whim", nor yet "The URI
u means what I mean to refer to when I use the URI u."  See Kripke again,
and note, to fend off an obvious misunderstanding, that the second formulation
is *not* circular even though it is useless.

John Cowan    cowan@ccil.org    http://ccil.org/~cowan
If a traveler were informed that such a man [as Lord John Russell] was
leader of the House of Commons, he may well begin to comprehend how the
Egyptians worshiped an insect.  --Benjamin Disraeli
Received on Friday, 14 March 2008 16:23:49 UTC

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