I am learning chord functions in major scales and supposedly the iii chord has a tonic function. however, the chord has a leading tone so shouldn't it be considered a dominant chord?
The idea is from German theory.
I don't know that theory well, but apparently the mediant chord can have both tonic and dominant function. The reason would be the overlapping tones of the tonic (
^5) and dominant (
My way of reconciling the leading tone
^7 being in a non-dominant chord (and also the dominant
^5 is in the mediant) is two-fold:
^3degree has its basic identity as a member of the tonic chord
- the absence of
^4- which could provide a dominant seventh - makes the chord less emphatically a dominant.
In other words the real dominant identity is
FA (in solfege) or scale degrees
^4. It may seem ironic but
^5 isn't so critical a factor, but keep in mind
^5 is in the tonic chord too; clearly not a dominant in that case.
RE make a good dominant. You might put it like this: the leading tone
TI and the absence of potential tonic tones - for practical purposes
RE - make a clear dominant. Then
^5 provides... I suppose tonal stability.
Having said that I thought the German theory treated the mediant chord as a dominant and the submediant as a tonic. Using the English terminology of the Wikipedia page the relative relations of
V/iii are somehow more fundamental that the counter-relative relationship of
I don't know how that theory is actually applied in analysis. I learned American theory where all seven scale degrees are discrete chords. I'm not sure how a analysis case is made for the mediant being either dominant (Dominantparallele) or tonic (Tonika-Gegenparallele.)