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Re: essential properties



To question #1:
Yes that was a typo.

I agree with your view that our definitions involve properties - those
which the definer chooses to include as essential to the concept which he
is (freely) defining.

I am contrasting this with the Aristotelian view - not of our language-
but of reality. In this view the essence (substance) of a thing exists
separately and apart from ANY properties.

To drive home the point - perhaps at some unintended risk of offending:
This view was (and still is) welcomed by the Scholastics as an
unassailable explanation of "transubstantiation": The essence/substance
of bread and wine can change to the essence/substance of a human body and
still keep all of the properties of bread and wine. This of course is
untestable, non-operational, and delightfully convenient. It is an
assertion of faith and cannot even be a conjecture of science. (Although
scientists can sometimes get similarly mired.)

"In the hard sciences we mostly talk about models rather than laws. And
if you talk to the people who are working on foundations of mathematics,
they also talk about models. It's certainly true of physics and astronomy
in particular that a law is just a model that we've got used to. . . . I
have enormous respect for Stephen Hawking, but I sometimes think he
doesn't know the difference between a model and the real thing. That's an
occupational disease of theoretical physicists."
-Freeman Dyson in ("A Glorious Accident", W. Kayzer ed.)

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor


----- Original Message -----
From: "John S. Denker" <jsd@MONMOUTH.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Saturday, November 30, 2002 3:08 PM
Subject: Re: essential properties


| Bob Sciamanda wrote:
|
| > I fail to appreciate the superficial vs accidental properties
distinction.
|
| I hope that meant to say "essential" vs "superficial and
| accidental" properties.
| |
To see the distinction, try this: Define "car" in terms
| of nthe essential properties. Then decide, is an SUV a
| car? Ifot, why not? Is a PT Cruiser a car? If not,
| why not? (Note that Chrysler swears it's not.) Is a
| non-street-legal kiddie-kart or dragster a car?
|
| This posting is the position of the writer, not that of Ford, GM, or
| Chrysler.
|
| This posting is the position of the writer, not that of SUNY-BSC, NAU or
the AAPT.

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.