[AZAMAT]
What was proposed but seem invalid is that we can always deduce
equivalence
of concepts by equivalence of individuals. This would not work where
there
is more than one possible aspect of the same individual or where there
is
change. (01)
[LEO]
I completely agree. One intensional description (or concept) is not
equivalent to another, even though both have the same extensions. But
(some) so-called natural kinds proponents ultimately want to make that
assertion, i.e., a description picks out the same extension in all
possible worlds. Of course, the strict realist (actualist) will say
that there is only one actual world, so we can instead substitute "same
extension in all situations in this world" for the above. That's
typically fine for "tigers" today. But eventually you end up saying
things like "well, today's planets are what used to be called planetary
bodies, and today's asteroids are was used to be called small planetary
bodies" (or something similar). (02)
The denotations may not have changed (the things in the world, if you
could know them in a God-like fashion, but then how can you?), but it's
definitely true that your ways of referring to them have changed. A
strict realist will say something like "well, natural kinds exist even
if we can't ascertain what they are or can only do so via the
application of the scientific method over time". But then (at least to
me) you get into green and grue discussions, and in today's
bioengineering world, perhaps in the distinction between "tomatoes" and
"tomatoes with 1 fish gene": i.e., when do "tomatoes with n other
genes" become non-tomatoes? You could revert to "natural" in "natural
kind" and say, well those kinds of cases are not natural. But what does
that mean: it begins to sound like "natural" arguments in religion. (03)
I too want ontological categories that correspond as much as possible
to things in the real world. But you're going to end up with
birds-that-can't-fly very soon, along with
tomatoes-that-have-no-tomato-genes-but-look-and-taste-like-good-old-tom
atoes. We all want necessary and sufficient conditions for our
"class/type" ontology "concepts/nodes/...", but we may not get them.
Axioms will help us here, so we can unambiguously state what we mean
(insofar as that's possible using logic, I guess ;). (04)
Leo (05)
_____________________________________________
Dr. Leo Obrst The MITRE Corporation, Information Semantics
lobrst@xxxxxxxxx Center for Innovative Computing & Informatics
Voice: 703-983-6770 7515 Colshire Drive, M/S H305
Fax: 703-983-1379 McLean, VA 22102-7508, USA (06)
-----Original Message-----
From: ontac-forum-bounces@xxxxxxxxxxxxxx
[mailto:ontac-forum-bounces@xxxxxxxxxxxxxx] On Behalf Of Cory Casanave
Sent: Sunday, January 22, 2006 1:35 PM
To: 'ONTAC-WG General Discussion'
Subject: Intension and Extension (Was RE: [ontac-forum] Type vs. Class
- lastchance to vote. ) (07)
Berry,
re:
>If 'rabbit' refers to a type, and if rabbit instances existed before
>human beings, and if rabbits were able to recognize other instances
>of like type (e.g. for dating purposes) then the type rabbit existed
>before any definition was formulated. Talk of types should thus not
>rely too much on talk of definitions/intensions. Indeed there are
>many types in biomedicine for which definitions have not yet been
>supplied, and many types in all domains for which incorrect
>definitions have been (or were for many centuries) supplied. (08)
[[CBC] ] While a bunch of furry creatures may have existed long ago,
the
concept of how these individuals are related is not part of the natural
world. That we may decide that a set of individuals is sufficiently
"more
similar" such that we classify them under a common term and concept it
is a
tool WE use that is a basis for how WE think and how WE communicate.
Certainly the first classification, one common to living things is
"food",
to a lion the distinction between "food" and "rabbit" may not even
exist.
Some pre-human may have had a thought or grunt for "Rabbit food", and
thus
was born the CONCEPT.
When we communicate such concepts we may do so by example (see, the
things
in this box are the "rabbit" I was talking about) or by definition.
Both
are ways to communicate and clarify the concept that we have in OUR
MINDS or
OUR logical formalisms. Classification by example appears to be how we
learn, but isn't this discipline about being a bit more precise?
So it would seem to me there are 5 things in play;
* An actual thing - jumping across my lawn
* A concept for a kind/classification/type of things - rabbit
* A definition for the concept - Small mammal, etc.
* Sets of things - creatures in a box
* A set of individuals satisfying a concept - "extent".
* Terms for the concept - EN:"Rabbit", FR:"Lapin" (09)
A concept <HAS> terms, definitions, sets and <AN> extent. (010)
What was proposed but seem invalid is that we can always deduce
equivalence
of concepts by equivalence of individuals. This would not work where
there
is more than one possible aspect of the same individual or where there
is
change. Perhaps there is a special kind of type where this kind of
assumption can be made. This special kind of type would have to have
individuals completely defined by a single definition and thus not
correspond to an individual in the real world. One example of such
types is
the enumerated types found in programming languages. "Color" may be an
example of such a type, but I am not sure yet. I am mostly sure
"Rabbit" is
NOT one of those types. So the more general concept is the type that
does
not contain this assumption. (011)
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