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

Re: Reification

From: Seth Russell <seth@robustai.net>
Date: Thu, 12 Apr 2001 13:59:20 -0700
Message-ID: <001201c0c393$733a8e00$b17ba8c0@c1457248a.sttls1.wa.home.com>
To: "pat hayes" <phayes@ai.uwf.edu>
Cc: <www-rdf-logic@w3.org>
From: "pat hayes" <phayes@ai.uwf.edu>

> You may have to give more axioms, yes, of course. But that just means
> saying a rather larger P, or asserting a whole lot of P's. That
> doesn't change anything.


>The more you say, the more you restrain the
> world; that is the very nature of asserting propositions. (That is
> surely WHY we ever assert anything: to express that the world is
> constrained in some way.)

Well it is quite a different thing to {restrain the world}, than it is to
{express that the world is constrained}.  The difference is between talk an
action.  You seem to have used both terms in your paragraph above somewhat
interchangeably, and I don't know to which you refer.  Thing is that when
you do logic with pencil and paper in relationship to a professor, you are
usually doing only the latter;  yet if you do it with a keyboard and a
powerful computer you can be doing both or either.  One hopes, of course,
that one is not just flapping one's lips here ... so me thinks we need to at
least provide for the former case ... especially if we're talking to the US
Defense Department, who might just attach the firing of a ICBM to somebody's

> However, you don't need to specify any operations. I'm not sure quite
> what you mean by that word in this context.

You can't get the computer to do anything without activating it's operating
instructions.  If you never activate those instructions, you are just doing
paper and pencil logic.

> Making an assertion does restrain the world, in that it makes some
> claims about the way the word is. But that doesn't 'close' the world
> in any useful sense. In fact it is notoriously difficult to close the
> world using logic: it is impossible to restrict the world to finite
> things, or to the natural numbers, etc..

Let me see if I can restate that paragraph from my point of view.

Making an assertion to a model does not restrain the world; rather it just
restrains that closed world model of the world.  Only when our model can
behave in the world, can such assertions indirectly restrain the world.  So
the computer's behavior *is* the interpretation.  Otherwise it's not only
notoriously difficult, but is actually  impossible, to restrict the world to
anything whatsoever just by using logic.  Or to say that more arrogantly:
Logic would be irrelevant.

> Truth arises from a relationship between expressions and
> interpretations, and has nothing to do with processes.

It's the interpretation part that always seems, to me, to get lost inside
the professor's head.   Precisely what does it mean, again?    But in
today's world we can (and do) substitute the computer for the professor's
head; and can arrive at more tangible results which actually do restrain the
world in a definite way.

     If I say P to the computer, the computer does Q;
     the computer's action is a real restraint on the world.

Isn't that a more tangible anchor of this notion of interpretation?

Where have I gone wrong?

Received on Thursday, 12 April 2001 17:02:33 UTC

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