RE: Operational Definitions

["JACK L. URETSKY (C) 1996; HEP DIV., ARGONNE NATIONAL LAB, ARGONNE, IL 60439" <JLU@hep.anl.gov>]

Hi all-
	Larry Smith writes:
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This particular example doesn't seem so bad, but I'm wary of operational
definitions in general.  My science education professor once asked us in
class what the definition of temperature was and a PhD physicist taking the
class with me responded with usual stuff about average kinetic energy.  The
Sci Ed prof said no, and no other student could come up with any other
definitions.  So after class I asked him what _real_ the definition of
temperature was and he said, "It is how hot or cold an object feels."  So
if I put my left hand in a bucket of cold water and my right hand in a
bucket of hot water, and then simultaneously plunge them both in a bucket
of warm water, the middle bucket has two different temperatures at the same
time?  And objects that aren't being felt have no temperature?  Does an
object that isn't being weighed at some instant of time have weight then?
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	Well, Larry, I think that you are trying to argue against a principle
by giving an example where the principle was ineptly applied.  That kind
of argument is illogical.
	I teach my students to use operational definitions.  If I want
to define a term that describes a concept ("distance" in Bridgeman's
classic example) I do it by describing the process that measures the
value associated with the concept (or term).  You will find, in general,
that the measurement depends upon the context in which the term is
used ("distance" across a room is different from "distance" from earth
to moon).  I teach this concept (following Dick Hake) by asking the
student to make a sketch of someone making the measurement.
	Note two consequences:
		1.  Use of operational definitions aids unambiguous
communication; and
		2.  There are words, phrases and concepts where
one does not know how to find an "operational definition"; in such
cases duelling, screaming, and shouting become appropriate techniques
for demonstrating why your "definition" is better than someone else's.
			Regards,
				Jack