I am enclosing below a copy of my posting to PHYSHARE. Hope this will
be of interest to the members of this list.
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Off and on one finds that the list members express their opinions about
suitability of a particular anology to explain a particular concept of physics
to students. Sometimes they express the fear that the anology may do more
harm than good. I want to offer the following observations about "Anology as
a means of valid knowledge" for their consideration.
When we use anology to explain something, we are trying to explain one natural
phenomenon in terms of ANOTHER natural phenomenon. The word ANOTHER implies
that there are differences between the two phenomena . If there are no
differences
they will be the same phenomenon. Or in other words a perfect anology for
a thing will be the thing itself and a perfect but/yet different anology cannot
exist. Teachers who want to use anology as tool in teaching have to keep
this point in their minds when they do so.
Indian logicians (logic of India is very old and developed independently)
have realised this aspect of anology and said that we have to do the
comparision with respect to only that aspect of the phenomenon for which it
is intended. An anlogy CANNOT BE AND THEREFORE SHOULD NOT BE stretched
too far.
If you want to say that since no perfect anologies exist we will not use
them in teaching for fear of inculcating wrong concepts in students, you
have confine yourself to mathematical models rather than natural models.
But if you think that natural models (anologies), though imperfect do
help the student to understand, you can use them.