Good points, William. A related issue that comes up in IT systems is that of software “versioning” and when is a version a new individual vice a new version of the same individual. For some purposes they may be identical, but for others, not.
And for software objects representing real world entities you have to deal with the degree of coupling that might exist between the software object and the real world entity, as well as whether that coupling might be deliberately altered or duplicated for operational purposes, such as training or entertainment (Second Life comes to mind). In such cases individuals essentially become classes with multiple instances of the same individual, usually with at least some different state parameter values representing the different contexts in which the individual is being represented. In such “virtual worlds”, physical contiguity and temporal history don’t necessarily constrain individuation. Developers are left to their own devices as to how they maintain distinctions among individuals in these situations
Hans
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of William Frank
Sent: Thursday, December 13, 2012 9:32 AM
To: [ontolog-forum]
Subject: Re: [ontolog-forum] Fwd: Ontologies and individuals
I agree that the distinction between individuals and kinds is a convention. But it seems as troublesome as it is necessary.
There is another aspect, neither trivial nor profound, but practical, though it has profoundly bothered many.
How do you know whether the class only has one member? Moslty, you only know of one **so far**. How do you decide whether two separate observations are observations of the same thing or of different things? If you use a set of attributes to define a class, if there just **happens** to be only one member, there might be instead zero or more, at some other time. Individual appear to be things such that every one is different from every other one, by definition.
I thought these days most people in the business of trying to understanding what it is to be an individual believe that it is *history* that differentiates otherwise identical things. This history, in the easiest instance, for physical things, usually involves contiguous locations in space through contiguous moments in time.
On Thu, Dec 13, 2012 at 9:14 AM, John F Sowa <sowa@xxxxxxxxxxx> wrote:
Dear Alex,
That question is either trivial or profound.
AT
> I am not sure I understand why an 'identification' of an individual
> thing is considered separately from a 'classification' of an individual
> thing. Personally I see the 'identification' requirement as a necessity
> to find out (define) a class of individual things which has only one
> member - that particular individual thing.
The trivial answer is that many logics make a sharp distinction between
individuals and types (or the classes or predicates associated with the
types).
If you have a logic that makes that distinction, then you identify an
individual by finding some symbol (such as a character string) that was
assigned as the name of that individual. But you classify an individual
by determining the names of types or classes of which it is a member.
But if you analyze the psychological, linguistic, and philosophical
issues, you'll find that there is no sharp distinction. What people
and other animals usually perceive are images of the types, and the
particular individual is inferred from the patterns of types and
the context (more patterns).
There are no sharp boundaries between images of distinct individuals,
images of the "same" individual at different occurrences, and images
of distinct, but similar individuals. All those distinctions must be
learned, and mistakes are common.
In short, the distinction between identification and classification
is a useful convention. Natural languages distinguish them, but NLs
are very flexible. They allow common nouns to be used as names
(Baker, Butler, Cook, Smith), and they allow proper names to be used
as common nouns (Xerox), verbs (Xerox), or adjectives (Xerox copy).
John
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