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[Phys-L] Re: Fields etc



According to what I just learned from The Internet Encyclopedia of Philosophy, a central tenet of Logical Positivism (or Logical Positism, if you prefer the, apparently, British spelling) is:

"A statement is meaningful if and only if it can be proved true or false, at least in principle, by means of the experience -- this assertion is called the verifiability principle. The meaning of a statement is its method of verification; that is we know the meaning of a statement if we know the conditions under which the statement is true or false.

When are we sure that the meaning of a question is clear? Obviously if and only if we are able to exactly describe the conditions in which it is possible to answer yes, or, respectively, the conditions in which it is necessary to answer with a no. The meaning of a question is thus defined only through the specification of those conditions...
The definition of the circumstances under which a statement is true is perfectly equivalent to the definition of its meaning.
... a statement has a meaning if and only if the fact that it is true makes a verifiable difference.
(M. Schlick, 'Positivismus und Realismus' in Erkenntnis, 3, 1932)."

See:

http://www.iep.utm.edu/l/logpos.htm#The%20Main%20Philosophical%20Tenets%20of%20Logical%20Positivism

Don Polvani
Anne Arundel Community College

-----Original Message-----
From: Forum for Physics Educators [mailto:PHYS-L@list1.ucc.nau.edu]On
Behalf Of Joseph Bellina
Sent: Tuesday, March 29, 2005 12:04 PM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: Fields etc


I'm not sure that the idea of operational definition...we know something
by how we measure it...is isomorphic with logical positivism.

joe

Bernard Cleyet wrote:

I was going to ask if you were from Vienna.

Halliday in his Intro. Nuclear Phys. (2nd ed.) devotes two pages on
Philosophy, mostly LP. He summarizes from The Nature of Physical Theory
and the Logic of Modern Physics

bc

Jack Uretsky wrote:

Michael Edmiston wrote:
-----------------------------------------------------------snip-------------------------------------------------------


Goodness... isn't that what we scientists say we are doing? Scientists
have similar lab exercises in which we ask students to observe something



cut

mental concept, nothing is real. We should not reify anything. (2)
Since we observe things and have learned to communicate these things to
others, and they observe them also, and they measure similar data, and
we all can draw predictive conclusions that we all observe to be born
out... everything that fits this pattern is reality.





_____________________end of quote_____________________________________
A solution -the one that I have adopted - was formulated long ago
by Percy Bridgman and described in his book "The logic of Modern
Physics". A concept is described by a measurement. Both Dick Hake and
I use this notion in our labs where a student defines a concept with a
sketch of a stick figure doing something. Thus, taking an example from
Bridgman, distance in a lab can be defined by someone making
measurements with a meter stick. Distance to the moon has a different
meaning, it may mean timing the delay of a radar pulse echo. The job of
the physicist is to determine the circumstances - and there better be
some - where the two definitions coincide.
Philosophers call this approach "Logical Positism", and some disdain
it. The ones who disdain it are not, to the best of my knowledge,
physicists.
Measurement has nothing to do with "reification", it does not
involve us in the semantics of "reality", and it always confronts us
with the real challenge of physics: find a way to predict the outcome of
new measurements before they are made.

Regards,

Jack



--
Joseph J. Bellina, Jr. Ph.D.
574-284-4662, 4968
Saint Mary's College
Dept. of Chemistry and Physics
Notre Dame, IN, 46556
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