[Smt-talk] "Neighboring" 6/4 Chords

[Dmitri Tymoczko]

> I find when instructing undergraduates in core harmony courses that students accept the guidelines we provide for part-writing much better if they understand the reasoning behind them. I'm at a loss, however, to explain why common-practice composers rarely used a 6/4 chord above scale degree 2 as a bass neighbor motion expanding tonic.

Sorry for being dense, but I'm not exactly sure I understand.  As I read it, you are asking for an explanation of why we don't often find progressions like:

(C4, E4, G4, C5)->(D4, D4, G4, B4)->(C4, E4, G4, C5)

I guess my first question is whether you can think of any common tonal progression in which a 6/4 chord acts in this way, with the bass moving in neighboring fashion (e.g. IV->I6/4->IV).  Off the top of my head, I can't think of one, on any scale degrees.  So "neighboring 6/4 chords" typically involve fixed bass.  But that's just a restatement of your question, I guess.

My second thought is that this sort of question has convinced me to abandon the term "neighboring 6/4 chord."  If you use the term, you create the (reasonable!) expectation that there is a general procedure here -- "6/4 chords can be used to create neighboring motion."  But common-practice music doesn't bear out this expectation.  The vast majority of "neighboring 6/4 chords" fall into just a couple idioms or schemas -- chiefly I->IV6/4->I and V->I6/4->V.  (I'd wager that upwards of 98% of the "neighboring 6/4 progressions" are in these two categories.)  Progressions like ii->V6/4->ii and vi->ii6/4->vi, which are perfectly neighboring, don't ever appear.

So I have reluctantly concluded that it's much better just to get rid of the terms "neighboring" and "passing 6/4" chords and to speak of a small number of idioms instead.  This more particular (idiomatic or "schema-based") explanation correctly gives the expectation that there are just a couple relevant progressions, occurring on specific scale degrees, and expressing specific harmonic functions.  The problem with more general explanations is that they suggest there should be a more general phenomenon, but there really isn't.

We've actually discussed this on the SMT list previously, I think.  There may be relevant posts in the archives.

DT

Dmitri Tymoczko
Associate Professor of Music
310 Woolworth Center
Princeton, NJ 08544-1007
(609) 258-4255 (ph), (609) 258-6793 (fax)
http://dmitri.tymoczko.com