John, (01)
I think we are getting somewhere, but I have a few more comments, which I
have added as I am afraid I do not understand the motivation for some of
your comments.
I realise that there may not be many other on the list who are interested,
but they have no obligation to read. (02)
>
> Chris,
>
>
> CP> By "extensional terms" do you mean (a) by extensional definitions
> > or (b) by an extensional criteria of identity. There seems to be
> > confusion about these terms, so can we agree to try and be clear
> > which we are using?
>
> Although I'm familiar with nonconstructive definitions in mathematics,
> I have strong a preference for constructive ones. And when it comes
> to ontology, my preference is extremely strong: any definition that
> cannot be used by a human being to recognize instances is useless
> for designing an intelligent system. (03)
I share this sympathy for both constructive maths and useful definitions -
though isn't it usually the argument/proof that is
constructive/non-constructive - a natural (useful) extension to definitions.
However, though extensional definitions are by nature constructive,
intentional definitions can be either.
Also, I believe many mathematicians would argue that non-constructive proofs
are very useful. (04)
>
> Some people complain that I am "confusing" ontology with epistemology.
> My response is that I want to (a) understand human psychology and
> (b) simulate something like it in a robot. For those purposes, a
> definition that does not support a clear-cut method for identifying
> instances is useless.
>
> CP> I and lots of others have been happily working on ontologies of
> > contracts, money, etc. for decades using an extensional criteria
> > of identity without any problems. Lewis, Heller, Sider and other
> > philosophers working in this area (also for decades) have not had
> > any problems with these kinds of entities.
>
> I have read such things, and I have a very serious problem with them:
> They can only be tested by God, who can not only view all instances
> spread out for all times and places, (05)
I am afraid I do not understand your point.
One talks about a terms/definitions (semantic) extension -
http://en.wikipedia.org/wiki/Extension_(semantics) - "the extension of a
concept, idea, or sign consists of the things to which it applies", this is
"in contrast with its comprehension or intension, which consists very
roughly of the ideas, properties, or corresponding signs that are implied or
suggested by the concept in question."
Note this not the same as
http://en.wikipedia.org/wiki/Extension_(metaphysics), which is the basis for
the extensional criteria of identity for individuals (and comes in 3d and 4d
varieties).
And for those, like myself, who are amused by such things is different from
the cheerleading stunt
(http://en.wikipedia.org/wiki/List_of_cheerleading_stunts ) (06)
Is your point that when one gives an intensional definition, for those with
a large enough (semantic) extension, only God can see the whole extension?
Or is it that one cannot practically give an extensional definition for
these?
I would agree with you, on both counts, and have made the similar points in
earlier mails in this thread, but I do not see how this is relevant. (07)
Just to be sure, we are agreed that we can give intensional definitions of
objects with extensional criteria of identity, aren't we? (08)
but who can peer into the hearts
> and minds of the actors to detect their innermost intentions. I do
> not consider any such definition to be a serious proposal for any
> computable application. (09)
I do not understand why one would need to "peer into the hearts and minds of
the actors to detect their innermost intentions" in order to know what is
money. Why do you think this is necessary? (010)
>
> CP> You earlier made an argument that said as money, etc. were
> > extrinsic properties they were intensional - which I pointed
> > out is incorrect.
>
> No. My objection was to defining intentional concepts by extension.
> Many extrinsic properties are easy to define by observable criteria
> -- for example, the "upper" berth of a bunk bed. (011)
But the wiki text I copied in the last email gave such an example (Prime
Minister is surely intentionally constructed). Is this wrong, and why? (012)
>
> But what counts as money depends on intentions, which are often
> difficult, if not impossible to detect without peering into the
> hearts and minds of the actors. A list of instances cannot, in
> general, show observable criteria for the intentions of the actors. (013)
Not sure 'money' is the example you want. The actors need to coordinate
their social constructions and as they cannot "peer into the
hearts and minds of the actors", they need observable mechanisms to do so -
so money could not exist if there were not these actor observable
mechanisms.
If you are saying that these observable mechanisms are not always observable
at a particular point in time (as they have already happened), that is true
and why a convention of observable records, such as written contracts
(including money) have grown up. (014)
So, if your point is that for socially (intentionally) constructed objects
(such as money), in some restricted situations, there will be no externally
observable criteria for the definition to use to determine what falls under
the definition, though the actors will have memories, intentions that guide
them. I agree. But am not sure what this has to do with our discussion, or
how it somehow invalidates an extensional criteria of identity. (015)
>
> John (016)
Chris (017)
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