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On 10/19/2015 11:50 AM, Thomas Johnston
wrote:
Pat, John, All:
I accidentally
deleted the entire thread, including your responses to my
comment of the 18th. So please re-post them. Nonetheless, this
gives me a chance to jump out of the details, and try to see
what the big picture looks like, at this point in the
discussion.
1) Quine and most
other logicians are find with associating ontological
commitment with the existential quantifier. Arthur Fine (an
outlier on this issue, I would think) prefers to associate
ontological commitment with the universal quantifier. But
those quantifiers, as quantifiers, are associated with "All"
and "Some", and so calling the latter the "existential
quantifier" begs the question I raised.
2)
Sometimes, in natural language, we want to say "All ...." in a
context in which we presuppose, and want and believe others to
understand that we are presupposing (cf. Grice), the existence
of what is referenced by the NP of the statement. At other
times, we presuppose that the reference of the NP does not
exist, and want and believe others to understand that we are
presupposing that the reference of the NP does not exist. Same
thing for "None ..." statements, same thing for "Some ..."
statements, same thing for "Some ... not" statements. It was
my belief that we want to be able to say all these things in
natural language that led to my original question.
3) I think
Pat offered a distinction between "exists" and "really
exists". This is a classic move to avoid accepting the
conclusion of a specific syllogism; break the middle term in
two. He makes a felicitous terminological suggestion:
associate "ontological commitment" with "really exists", and
commit to it by explicitly using "really exists" as a
predicate. (I think this commits Pat to Anselm's Ontological
Argument, but I'm not sure.) The other term he offers is
"referential commitment", which he associates with the
"exists" that logicians tie to the "Some" quantifier. And he
explains referential commitment as ontological commitment
relativized to a specified universe of discourse. That's a
very nice move, and the explanation is persuasive. But it
doesn't work for ordinary un-typed FOPL, since the universe of
discourse for that logic (I think) is [Everything that Exists
and Nothing that Doesn't]. However, perhaps when we talk about
dragons, in natural language, Gricean conventions lead us to a
presupposition of a universe which is not the "real" one", but
is rather the real one supplemented with some fictitious
entities (e.g. Tolkien's universe).
Thomas,
It is best that an ontology is defined for a specific use. There
is a vast difference between the database world and the otherwise
closed or fully open world. In fact, every existence has some
scope associated with it. It is just that it gets ignored or we
assume that it is such and such. The "really exists" is
appropriate for an open world application which should also allow
for speculative, fictional and fantasy contexts. That is why, in
Euro/US culture, we tell children "Once upon a time...". We are
defining the context to make it clear and easier for the child or
reader to understand the setting.
If you say "really exists" you are contrasting it with some other
context or scope and the other(s) should be defined. And "really
exists" is from a perspective and therefore subjective, and should
have a frame or facet disclosed as part of that definition. If the
context is not defined for the ontology then we should assume it
is...what? Undefined, defined for closed world, from an unknown
POV, or for a fully open world? If there is not a specified
definition then we should not be surprised if there are
miscommunications.
-John Bottoms
Concord, MA USA
4) So I'm
ok with this: NPs have referential commitment no matter what
universe of discourse their statements are relativized to. But
NPs have ontological commitment relativized only to universes
of discourse which contain as referents things we believe
really exist. This feels like an elaborate tautology to me,
but it's what I make of Pat's distinction between referential
and ontological commitment, and I don't know any
non-tautologous way of stating it.
5)
Referential commitment is made with referring expressions such
as names. It is no more closely tied to the "Some"
quantification than it is with the "All" quantification. This
seems obvious to me but, I believe, does not seem obvious to
either of you. But intuitions, expressed as "seems obvious" or
otherwise, are not arguments. FOL, as John said, ain't broke.
OK. But I'd add that FOL isn't a Swiss Army knife. It has
limitations, illustrated by the extensive work done on various
forms of intensional logics.
6) Prior to
Pat's referential vs. ontological commitment distinction, I
said that I thought ontological commitment could be made with
specific uses of the "All" quantifier, and withheld from
specific uses of the "Some" quantifier. Now I will use Pat's
distinction and say: referential commitment can be made with
any NP, regardless of whether "All" of "Some" is the
quantifier used with it. But this is to rephrase my original
intuition, so I suppose that the intuition you both share is
different.
7) I had
things I wanted to say about Pat's reply last night. One I
will mention here is that, in my original quotation from the
SEP Ontological Commitment article, I was not trying to pull
the wool over anyone's eyes by leaving off the phrase
"According to the third objection to sufficiency". I realize
how lonely it is, where I stand on this, and never meant to
suggest anything else.
8) I am
grateful for this extended discussion. I now have a much
better understanding of why I asked the original question, and
where in the beautiful labyrinth of formal logic I might end
up (at the Minotaur?) if I continued down the path of
separating commitment from quantification.
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