W3C home > Mailing lists > Public > www-rdf-logic@w3.org > April 2001

Re: Reification

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 9 Apr 2001 14:04:44 -0500
Message-Id: <v04210112b6f7b4f7be93@[]>
To: "Seth Russell" <seth@robustai.net>
Cc: www-rdf-logic@w3.org
>From: "pat hayes" <phayes@ai.uwf.edu>
> > >From: "Graham Klyne" <GK@ninebynine.org>
> > >
> > > > Until this, I never got any sense that open world negation was
> > > > impossible.
> > >
> > >Maybe that's because open world Truth is impossible too.  Rather Truth is
> > >relative to active processes. Perhaps the best we can hope for is a kind
> > >propositional attitude that each agent calculates for it's self.
> >
> > What on earth are you guys talking about? Truth and falsity have got
> > nothing to do with the openness or closedness of the world, and
> > nothing much to do with activity or processes.
>Well I can't speak for Grahm, but I hope I know what I meant.   Now I will
>be talking quite informally, so if i mis apply a precise term, I apologize
>in advance, and would ask for you to try to look behind my sloppyness, for
>whatever, if anything, may lie beneath.

I'll do my best.

>If someone creates a formal system in which all axioms, syntax, and
>operations are specified;  then the statements of such a system can be
>considered True\False and we can operate on that state with negation.  I
>would call such a system "closed".  The opposite situation is where the
>axioms and operations are not all known - perhaps the only thing that is
>known is the syntax of the statements.  I would call such a system "open".

OK. This is the normal case that formal logic deals with and to which 
the terms 'true' and 'false' usually apply. If I say that P is true, 
I havn't thereby said anything about anything else, or claimed that 
the world is closed or limited in any way other than that P has to be 
true in it, or pre-empted anything that anyone else might want to say 
about the world (unless they diasagree with me on this one 
proposition, of course) . For example, if I say that Foodles exist, I 
am not saying that nothing but Foodles exist. (I am also not saying 
that the opposite, by the way: I'm just not saying anything about the 
rest of the world at all, so it can be anything it wants to be 
without my claim being false; just so long as it has some Foodles in 

Similarly if I say that P is false, which is the same thing as saying that
(not P) is true.

>My thesis, of course, is that the real world, that world in which we human
>agents seem to live and also the world we inhabit when we surf the web, is


>and that there does not seem to be any absolute or formal meaning to
>the description of statements as True\False or the negation of that

No, that doesn't follow in any way. In fact I am puzzled as to why 
you see any connection between truth and falsity, on the one hand, 
and the size or openness of the world, on the other. They don't seem 
to have anything to do with one another.

> In other words Truth in the real world and on the web is

Relative to what? But in any case, this seems like yet a third topic 
that also has nothing to do with either of the other two, which is 
exactly what it means to claim that P is true. For myself, I prefer 
not to go into those waters unless absolutely compelled to, since 
there don't seem to be any fish there, but Im willing to go along if 
you want to try sailing. So, to repeat, relative to what?

Pat Hayes

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Received on Monday, 9 April 2001 17:02:37 UTC

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