Throughout my whole career including student time I have had a feeling
that leaning and teaching electromagnetism, especially macroscopic
Maxwell equations (M-eqs) is dif?cult. In order to make a good use of
these equations, it seemed necessary to be able to use certain empirical
knowledges and model-dependent concepts, rather than pure logics. Many
of my friends, colleagues and the physicists I have met on various
occasions have expressed similar impressions. This is not the case with
microscopic M-eqs and quantum mechanics, which do not make us feel
reluctant to teach, probably because of the clear logical structure.
What makes us hesitate to teach is probably because we have to explain
what we ourselves do not completely understand. Logic is an essential
element in physics, as well as in mathematics, so that it does not
matter for physicists to experience dif?culties at the initial phase, as
far as the logical structure is clear. As the we- known principles of
physics say, "a good theory should be logically consistent and explain
relevant experiments". Our feeling about macroscopic M-eqs may be
related with some incompleteness of their logical structure.