W3C home > Mailing lists > Public > semantic-web@w3.org > March 2011

Re: thisiness

From: Pat Hayes <phayes@ihmc.us>
Date: Sat, 26 Mar 2011 16:33:20 -0500
Cc: nathan@webr3.org, Henry Story <henry.story@bblfish.net>, SW-forum Web <semantic-web@w3.org>
Message-Id: <86909121-545C-4D0C-B36F-9B400A93FB6F@ihmc.us>
To: Gregg Reynolds <dev@mobileink.com>

On Mar 26, 2011, at 5:07 AM, Gregg Reynolds wrote:

> On Fri, Mar 25, 2011 at 2:59 PM, Pat Hayes <phayes@ihmc.us> wrote:
> 
> On Mar 25, 2011, at 12:02 PM, Gregg Reynolds wrote:
> 
>> On Fri, Mar 25, 2011 at 9:41 AM, Pat Hayes <phayes@ihmc.us> wrote:
>> 
>> No, this does not follow. Skolemizing replaces an existentially bound variable (a bnode) with a logical "name", but this does not imply naming in Even's sense. A logical name need not be a proper name. So, given the two indistinguishable balls in Evens' basin, I can pull a mathematician's trick and say, "call them A and B". This does not "name" either one of them in the sense of being able to identify the particular referent of the name, but it does enable me to say things about the balls in the basin.
>> 
>> I'm afraid not.  It allows you to say things about some imaginary "things" you name A and B (i.e. it allows you to state generalities); it does not allow you to say things about THE particular balls in THE particular basin.  That's rather the point of the exercise, I should think.
> 
> I disagree. It does enable me to speak of the balls in the basin, the actual balls. There are truths about them which do not require them to be individually identified, like the one I mentioned. 
> My use of ungrounded non-rigid names does not make their referents imaginary. The non-rigidity comes from the fact that the names can be interpreted w.r.t. the intended interpretation universe (in this case, two balls in a basin) in more than one way. It might be this ball that is called 'A' and the other that is called 'B'; or, it may be the other way round. Without rigid reference, I cannot be sure which.
> 
> Right.  But what you can be sure of is that whatever you say about them can only be contingently true at best.

Well, of course. Most of what is said in most data is contingently true, right? Necessary truths tend to get incorporated into mechanisms.

>  In particular, A and B could refer to the same ball, rendering "A != B" false.

That is in one interpretation, yes. Which is why the sentence is worth saying: it conveys something factual about the world being described, by ruling out those interpretations in which it is false. The utterance of necessary truths rapidly gets rather boring. 

>  Furthermore your interpretation would be private

The statement, and what it conveys about the world being described, can be public. The proposition it expresses is publicly accessible. Which is the best we can hope for :-)

> , since nobody but you would know what you intend by using the names.  Which effectively means you cannot name them.
> 
> I'm not sure why this is off list.

Oh, neither am I. Sorry, just hit the wrong button. I will put the CCs back in this reply.

>  ...
> 
> Perhaps, but not on this particular topic. The idea that model theory is about 'imaginary' things because it is couched in terms of set theory is a widespread fallacy, but it is none the less fallacious for all that. 
> 
> I meant "product of the imagination", i.e. mind.  Like numbers.  We're not all Platonists, you know.

Whatever. My point is that the sentence can be about the actual balls in the actual basin, even with non-rigidly referring names in it. 

Pat

>  
> -Gregg
> 

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Received on Saturday, 26 March 2011 21:34:05 UTC

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