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I am just cracking into a book on basic Harmony (Mark Sarnecki, 2nd edition), and the first section begins with a review of the triads built on each degree of a C major scale, as shown in this picture.

Screenshot 1

Then after introducing the various types of 7th chords, the same sequence of chords is considered, along 7th chords built on the supertonic and dominant of the C major scale, as shown below.

Screenshot 2

It results in a minor 7th chord built on D, and a dominant seventh chord build on G.

My actual question:

It seems rather arbitrary that we've only done this on the second and fifth degree of the scale. Why not build a minor 7th chord upon E as well? or a major 7th chord on F? or all of the notes in the scale for that matter?

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    We do. As for why he didn't, I have no idea. That's to say that you can build triads or 7th chords or 9th chords or whatever from any degree of any scale by stacking 3rds. – user37496 Jan 10 '18 at 3:16
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    Yeah I don’t know about anyone else but I build seventh chords on other scale degrees all the time. – Todd Wilcox Jan 10 '18 at 5:08
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    If I'm allowed to be really cynical, then here is my immediate thought: Some people think that music theory is a way to decide whether something sounds good or bad, and a recipe for how music ought to be written. In reality, it's just a glossary and language developed so that we can discuss things like what sounds good or bad, or what characterises different music styles, in a constructive manner. By omitting things, it seems like this book tries to say that such things don't exist, or just that "that's not something we do", going directly against the purpose of music theory. – Arthur Jan 10 '18 at 12:38
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    Yes, in short: You can do whatever you want, but some things are uncommon in conventional use. I see this attitude of "what are we allowed to do" as well as accepting conventions of use and nomenclature as though they were facts of Nature all over the place on StackExchange, and suspect that they're rampant in music in general. You don't even have to stick to Equal Temperament, a tuning which I'm sure some or even many musicians have lived their entire lives believing provided the sole primary colors of harmony. – Epanoui Jan 10 '18 at 15:28
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    I suspect this is focused on "very" classical music, where these two chords the main chords that a seventh are added to (I don't know why this is. The idea of the seventh was still a relatively new concept) – MCMastery Jan 10 '18 at 21:38
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We do! It's just that that book doesn't...yet.

We build seventh chords on all scale degrees; the seventh chord on scale-degree 3 in major, for instance, is a minor seventh.

But beginning musicians, especially those in the popular genres, get the most bang for their buck with seventh chords on scale-degrees 2 and 5 so that they can create that nice circle-of-fifths ii7-V7-I progression.

This book is almost certainly only presenting those two seventh chords for easy clarity early on.

This text is the "basic" Harmony by Sarnecki. The book comes in three volumes (Basic, Intermediate, Advanced), and based on the Amazon description for the Intermediate volume, the seventh chords you mention are found there:

The Intermediate level addresses fundamentals of harmonization; harmonic sequences; leading-note and other diatonic 7th chords; tonicization and secondary dominants; modulation; dominant 9th, 11th, and 13th chords; the Bach Chorales; form and analysis; and melody writing.

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    "We do" ... Jinx! – user37496 Jan 10 '18 at 3:18
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    @user37496 <user is unable to comment on account of the jinx> – Richard Jan 10 '18 at 3:19
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    "Or maybe it just doesn't yet" Quite likely. If there's one thing a beginner book shouldn't do, is smash down the entirety of music theory all at once. I suspect the author simply used this subset because it fit his approach best. – Mast Jan 10 '18 at 8:58
  • We certainly do! To the extent that most of us seem to use ii7 > V7 > Imaj7 more than just I for resolution. Maybe, later in the book, it gets into all that - it jolly well should ! Perhaps with a footnote on the page shown, to whet the reader's appetite? – Tim Jan 10 '18 at 9:39
  • Thanks for the clarification. If I am understanding correctly, I could just as well have added a seventh on to every triad; but the author simply chooses to emphasize those two first. – Kyle Schlitt Jan 11 '18 at 23:09
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In jazz and modern classical music, all kinds of 7th chords and beyond are used. But in the past, the most common 7th chords in classical music were built on the supertonic and dominant scale degrees for a very simple reason.

The ii chord and IV chords function as subdominants Mash them together and you get a iim7. The V chord and the diminished vii function as dominants. Mash them together and you get a V7 chord.

These 7th chords developed because of the shared function, but also because the m7 created a dissonance that was not so striking and out of place in the music.

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    Brilliant! I never thought of that! +1! – user45266 Nov 5 '18 at 4:20
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    @MaikaSakuranomiya, as I said in my answer, in jazz and modern classical music all kinds of 7th chords and beyond are used. The vi9 was not used in older classical music. In the key of C Major, the addition of a B in any chord would introduce the leading tone which would negate any tonic function. – Heather S. Apr 1 at 10:56
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Why not build a minor 7th chord upon E as well? or a major 7th chord on F? or all of the notes in the scale for that matter?

You are reading way too much into things: Nowhere in the content you posted does it say that 7th chords are only built on those two scale degrees. It's simply an opening exercise introducing 7th chords in two of their most important, common usages in western music.

As others have mentioned, we can and do build 7th chords on any note of any scale, and certainly the book deals with other types of 7th chords further on.

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    When absorbing material for the first time, many things are not obvious at all to a beginner even though they are crystal clear to an expert such as yourself. Thank you for your addition. – Kyle Schlitt Jan 11 '18 at 23:07
  • @KyleSchlitt - Thanks, but I'm not an expert - I just know a few things. There are experts on here, but they don't include me. – Stinkfoot Jan 12 '18 at 6:20
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    This is what the user actually needs: an explanation they they have misread their textbook. – Michael Curtis Feb 27 at 14:57
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Why would we ever build seventh chords only on the 2 and 5 degrees?


We have seventh chords on all seven degrees. In C-major, these would be:

  • Cmaj7 (I7)
  • Dm7 (ii7)
  • Em7 (iii7)
  • Fmaj7 (IV7)
  • G7 (V7)
  • Am7 (vi7)
  • Bm7♭5 (viiø7)

It makes no sense that we would only build seventh chords only on the 2 and 5 degrees. All chords are built on all seven degrees. To be honest, I've seen all of them, leaving out none!

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To complete the picture, we have major and minor triads, and to each we can add a

major or minor 7th: MM7(M7), Mm7(7), mm7(m7), mM7 (rarely used).

         key C: CM7 FM7 GM7, G7,     Dm7 Em7 Am7, DmM7 EmM7 AmM7
  • This doesn't really answer the question here. -1. – Maika_Sakuran0miya Jun 19 at 5:31
  • The question was if we only build 7th off of supertonic and dominant. The answer shows that they are build off any chord, and identifies the mM7 chord as another example of a 7th that was not even discussed. – Terry Shannon Jun 19 at 16:31

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