
And has been rather thoroughly demolished as myth by Robert Scott Root-
Bernstein.  See his book, "Discovering".  Ring structures for benzene
had been proposed before Kekule', after him, and at the same time as him.
The current models do not resemble Kekule's.  Many of the predecessors
of Kekule's structure resemble the modern model more.

I don't think "extra-scientific" is a very useful phrase in a discussion
of the boundaries of science, except as a proposed definiens.  Extra-rational
is a better phrase.  In fact, there are quite a number of well-known cases
of extra-rational considerations driving science in a useful direction.

For example, Pasteur discovered that racemic acid was a mixture of
enantiomers (the origin of stereochemistry) partly because he liked a
friend's crank theory of chemical action.  The friend was wrong, but
Pasteur's discovery stood.  A prior investigator (Mitscherlich), looking
at the same phenomenon, had missed a crucial detail; presumably because he
lacked Pasteur's motivation to find something that distinguished racemic
acid from tartaric (now we say: d-tartaric) acid.

Again, Pasteur discovered the differential fermentation of enantiomers
(tartaric acid again) not because of some rational conviction, but because
he was trying to produce yeast that lived on l-tartaric acid.  His notebooks
contained fantasies of becoming the "Newton of mirror-image life," which
he never admitted publically.

Perhaps the best example is the discovery that DNA carries genes.  Avery
started this work because of one of his students, and ardent Anglophile
and Francophobe Canadian, defended Fred Griffiths' discoveries in mice.
Most of Griffiths' critics were French, which decided the issue for the
student.  Avery told him to replicate Griffiths' work in vitro, which the
student eventually did, whereupon Avery was convinced and started the
research program which, in 15 or so years, produced the famous discovery
(Avery, MacLeod, and McCarty, JEM 1944).