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Re: URI Declarations [Usage scenario 1b]

From: John Cowan <cowan@ccil.org>
Date: Mon, 3 Mar 2008 12:48:06 -0500
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: <20080303174806.GA1565@mercury.ccil.org>

Pat Hayes scripsit:

> And one can give many others, of course. But you are talking about 
> essential properties - what in OntoClean are called, if memory 
> serves, "rigid" properties. Whereas what David requires us to put in 
> our declarations are "identifying" properties, those which are 
> supposed to pin down a referent uniquely. These are not the same 
> notion. Being human, as a property of a human, is necessary (rigid) 
> but it is most emphatically not 'identifying' (until we get the point 
> of there being only one of us around.) In fact, necessary properties 
> tend to be of the least use for identification, precisely because, 
> being necessary, they tend to be shared by everything else in the 
> relevant category. If you want to identify me uniquely, you will do a 
> lot better knowing my SS number (not essential or rigid in any way) 
> than the essential fact that I am human.

It's true that lots of essential properties aren't identifying in
themselves, but the more essential properties you know, the better a
job you can do at identification.  Because your SSN is not essential,
there may be another person who has the same SSN (such glitches are not
supposed to happen, but do).  Your DNA dump, though, *is* essential,
and (given that you are not an identical twin) completely identifying.

We sometimes find it useful to treat non-essential properties like
name+DOB or SSN as identifying, but such treatments are always heuristic
in nature, always subject to being debunked thus:  "No, I meant quite
a different James Earl Carter born on 1924-10-01."

This can come up in real life.  I once volunteered to help check
election records to identify a possible election fraud, and thought I had
found a hit -- but it turned out to be two sisters (or perhaps cousins)
living in the same house with identical first and last names (presumably
different middle names) and nearly indistinguishable signatures.  A close
inspection showed that they had been signing each other's election
cards at random for years, but there was no actual fraud involved,
just a nearly inextricable confusion of identity.

> Overall, I'd suggest that this entire discussion is so hopelessly 
> muddled that the proposal is best dropped before we generate even 
> more confusion. At least, lets see some convincing examples of what 
> might constitute an appropriate 'declaration' before proceeding. I 
> don't think that "identifying properties" exist. Can anyone prove me 
> wrong?

As Quine says, there is no entity without identity, so if we wish to
drop identification, we will have a very difficult time distinguishing
things at all.  If nothing else, it is identifying to say that object
o of sort s occupied space-time coordinates (x, y, z, t) relative to
some convenient origin.  (I introduce "sort s" because although my liver
occupies some location at the present moment, I occupy it too.)

Quantum theory aside, we do not want to treat classical objects as if
they were cloudlets in a buttermilk sky, where it makes no sense to ask
"Is this one the same as that one?"  Too much of logic and science goes
down the rabbit hole.

-- 
Evolutionary psychology is the theory           John Cowan
that men are nothing but horn-dogs,             http://www.ccil.org/~cowan
and that women only want them for their money.  cowan@ccil.org
        --Susan McCarthy (adapted)
Received on Monday, 3 March 2008 17:48:28 GMT

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