>> -----Original Message-----
>> From: Pat Hayes [mailto:phayes@xxxxxxx]
>> Sent: 19 March 2007 18:38
>> To: Chris Partridge
>> Cc: '[ontolog-forum] '
>> Subject: RE: [ontolog-forum] Ontological Assumptions of FOL
>> >>CP>I am not sure where you see the disadvantages of the DavidL position
>> >>described are. He is saying that if the instances are spatio-temporal,
>> >>there some sense in which the set of them are as well.
>> >PH>Well, I can see a lot of problems with this. If
>> >you believe, for example, that all spatiotemporal
>> >entities are in some sense physical, you will get
>> >into trouble.
>> >By physical do you mean something more than material? Not sure what
>> >ensue - could you elaborate.
>> You might for example get the conclusion that since all physical
>> things are made of some kind of stuff (Cyc has such an axiom), that
>> therefore numbers are made of some kind of stuff. Then there could be
>> questions about the density, say, of 17-stuff.
>A number of points:
>1) the argument (see above) went: if the instances are spatio-temporal, so
>is the set, in some sense. You are taking the argument the other way from
>sets to instances. Neither I nor DavidL made this claim.
>2) one needs to be careful about what counts as a kind of stuff, matter?,
>space-time? (DavidL has an interesting footnote on this. Often there is a
>notion of physical that it tied to matter, with a more general notion tied
>to spatio-temporal. Maybe this is where the disconnect is.
>3) If one has a Fregean notion of number, then as the set of all (actual and
>possible?) sets with 17 members would have an infinite number of members
>working out the density would be difficult, if not impossible. But not
>absolutely meaningless. However, I have already agreed numbers pose
Sure. But we are beginning to engage in
philosophical debate here, and my point is more
practical. Other ontologies WILL have (perhaps
oversimplified) assumptions like this in them.
Cyc for example, which for all its faults is
probably the most highly engineered and tested
ontology ever built, has an axiom to the effect
that every sphere in space contains (in fact, is
filled) with a certain kind of stuff at each
moment in time. This means that there an awful
lot of kinds of stuff - such as 30%
water/60%air/10%mackerel - but that doesn't
matter in practice. But if sets had a
spatiotemporal extent, then there would have to
be kinds of set-stuff. Which I guess there could
be, consistently (maybe DavidL would find this
congenial) but my own intuition is starting to
give up at this point. I have no idea where to
take such an ontology, or how to get any sense of
what would be sensible in it. It feels like a bug
to me. (02)
>> >PH>Or if someone else believes this
>> >and bases *their* ontology on it, and then you
>> >try to work with them. Many high-level frameworks
>> >make the spatiotemporal/abstract distinction very
>> >high up, so get into difficulties when it is
>> >denied. And DavidL's position as I understand it
>> >is that this is so when the members are
>> >spatiotemporally close: but what of highly
>> >scattered examples, such as the set of all the
>> >hydrogen atoms?
>> >Ah, I think we are talking about different things here.
>> >If you are saying that a lot of existing ontologies have X therefore we
>> >to have something that can work with X - I can see the argument.
>> That was my main point, yes.
>> >My point is rather that if 'abstract' is a bit difficult to get a clear
>> >picture of - then people using it will end up with different
>> >- making things difficult to reconcile. My tactic would be to just take
>> >abstract out of the hierarchy - not sure what kind of problems this would
>> I agree that just tossing a tricky distinction is often a good
>> strategy under these circumstances. But I tend to think that most
> > folk agree fairly well on the abstract/spatiotemporal division, in
>> fact, and that DavidL is rather an outlier. He has a number of rather
>> odd realist views, of course, including possible worlds.
>Ad hominem argument (though with some substance). However, I think his basic
>point is so simple and obvious, that one needs to face up to it. (03)
I face up to it, and I deny it. I don't think its
at all obvious. In fact, this is one of the
reasons why we say a collection (like a flock of
sheep or a herd) isnt a set, because the flock or
herd *is* spatiotemporal. I prefer to say that
sets are fictional (but useful) than that they
are somewhere and somewhen. (04)
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