Pat C, Pat H, and Ron, (01)
RW> [Pat H's reply to Pat C] does look like some things worth keeping
> for more than the time it takes to read an e-mail and press delete. (02)
I agree. I'd just like to summarize and emphasize a few points.
In the following summary, the quoted sentences are by Pat H, and
the unquoted sentences are by me. (03)
1. "Tarskian semantics... is a very general theory of meaning, one
that can be applied to a wide range of languages and notations." (04)
Yes indeed. In fact, *every* theory of formal ontology that anyone
has proposed in the past half century is based on a Tarski-style
semantics. That includes Cyc, SUMO, BFO, Dolce, etc., etc., etc.
It also includes the semantics for every digital system (hardware
or software) that has ever been designed and built since the 1940s
-- including those for which the designers had no idea what a
formal semantics is or might be. (05)
2. "It is just wrong to draw the contrast between the natural things,
on the one hand, and the account provided of those things by a
theory of them, on the other, as a difference of **kind**." (06)
Yes. Every statement in logic is absolutely precise. The common
words used to define the subject in Longman's dictionary (or any
other dictionary written by lexicographers for human readers) are
usually rather vague and shift their meanings slightly from one
definition to the next. But that vague cloud of meaning *includes*
the formally defined meaning. The vague meaning covers more cases
and it has a fuzzier boundary, but each precise meaning contained
in the could is just one very sharply defined sense of the same
nature as any other word sense in the cloud. (07)
3. "Computational ontologies are artifacts, written in formal logical
notations." (08)
Although I agree with that statement, I suspect that Pat C was
claiming that programs have some meaning other than what is
captured in a formal logic. But it is important to distinguish
a declarative statement (in a usual logic) from an imperative
statement, such as a command or a machine instruction. But every
machine instruction and every program written for a digital
computer can be completely defined in the following form: (09)
Preconditions, Action, Postconditions. (010)
The preconditions and postconditions are statements in logic,
which can be formally defined by a Tarski-style semantics.
The preconditions describe the state of the computer system
before the action, which may be a single machine instruction
or an arbitrarily large program composed of many instructions.
And the postconditions define the state after the action. (011)
The action itself has no meaning outside what can be described in
the logic used to state the preconditions and the postconditions.
The human commentary may explain what the programmer or designer
had intended, but if there is any discrepancy between the comments
and the program, there is a bug (or *issue* as MSFT calls it). (012)
Pat C has repeatedly made the following claim to justify his search
for primitives: (013)
PC>> So, if we want the meanings of terms in an ontology to remain
>> stable, and **don't** want the meanings to change any time some
>> remotely related type appears in a new axiom... (014)
PH> But we DO want this! Surely that is the very point of changing
> and adding axioms. If meanings are stable across theories, then
> what is the point of adding axioms to capture more meaning? (015)
I'd like to clarify the kind of change that occurs when more axioms
are added. Each addition of an axiom to a theory is a specialization.
The change it makes *narrows* the meaning of the terms in it. For
example, the term 'Animal' is very broad. By adding more qualifiers
(axioms), the meaning can be specialized to 'Dog'. Further axioms
can narrow it to 'Poodle'. (016)
Those are certainly changes, but they don't go outside the cloud
of meaning of the original term. In fact, every dictionary written
for human consumption uses such definitions. (017)
John (018)
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