Re: syllogism

From: patty (pattyNO_at_SPAMicyberspace.net)
Date: 10/01/04 

Date: Fri, 01 Oct 2004 04:51:37 GMT

Wolf Kirchmeir wrote:
> patty wrote:
>
> [...]
>
>> Well i see where we are stumbling over the rather ambiguous (A-->B).
>> I was interpreting it as a first order term with *one* property and no
>> quantification (Fa => Fb); but now i see you meant it as (for *all*
>> properties F, Fa <=> Fb) which *is* a coding of the definition of the
>> identity of a and b:
>
>
> Sorry, I thought A-->B was a commonly understood representation of "If
> A, then B", or "A implies B." I also think that since I used this
> symbolism in the context of implication, it should've been clear to you
> that's what I intended. I use => only as "equal to or greater than",
> never as a logic operator.
>

I knew you were talking about implication. "=>" and "<=>" are what KIF
uses; but that didn't matter, that was not where the communication broke
down.

> Thus A-->B is false if "A true", and "B false", and true otherwise. If
> A, B are truthfunctions, then sometimes (A-->B ANDF B-->A), and
> sometimes not - depends on A, B. IOW, [(A==B) iff (A-->B AND B-->A] When
> it comes to truthfunctions, that does not mean A, B are
> indistinguishable. It means that either can be transformed into the
> other, but that operation is meaningless unless A, B were
> distinguishable to start with. Right?
>

Right, you are talking about material implication and material
equivalence of *propositions*. Guess what? ... i was talking about
identity of *objects*. You started out talking about what you called
"logical identity" and then went on to talk (using the same symbols)
about "an observable event", which i took as a logical object and not a
proposition, which of course is not observable. I think that the
identity of objects and the equivalence of propositions are quite
different things. You correctly quoted the definition of the latter, i
  the definition of the former. It's a good thing we don't have to
reason together, huh?

<http://groups.google.com/groups?selm=Zfj6d.5698%24tT2.761154%40news20.bellglobal.com>

> Whether it makes sense to say that A, B have the same properties in this
> case I'll leave to other thinkers.

Well it doesn't make sense to me to say even that propositions have
properties - nor would that have been anything that you got from me.

> I'm getting leery of the term
> "property."
>

Don't take my use of "property" too seriously here ... by "Fa" i just
mean that "F" is a proposition about an object "a" ... (Skinny-woman,
Big-man, etc) pretty standard FOPL i should imagine.

In any case, all i was trying to get around to was the relationship
between some of the laws of logic specified in the diagram below ...
what a round about way to do it .. huh?

<http://icyberspace.net/patty/diagrams/logic-laws.jpg>

patty

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