And, to be fair, that Alan Pollock I quoted before tends to agree with you DooWahDiddy, but reading further on, he does say: “Again, one can make a “theoretical” argument that the harmony here is, structurally, just a droning i chord. But even those who might agree with this perspective will still acknowledge the extent to which the inner voice here connotes that saddened, sighing gesture.” And I completely agree with that.
Yeah, you’re right, I didn’t go back and check. I can see your point, too; like I said, it’s really just a matter of defining the terms and making a judgment call. I guess you’d also have to decide if bass notes make a chord “different”, too; i.e. if I go C, C/E, C/A, C/G, is that a 4-chord song or just one?
Definitely something that would be contextual. Just played straight through, with no further context, I’d probably just call it one chord. But it depends on what else is going on. Sometimes a slash chord is just a simplified way of expressing a more complicated harmony. Sometimes it’s just the bass moving around.
That was one of the parts I meant, I think…
The vocal line has to be included in understanding the song, especially if in a certain song the vocal frequently includes notes that redefine the chord.
For example, if you wrote a song where the guitar played open fifths a lot and the vocals kept switching between major and minor thirds, and sometimes threw in sevenths, the guitar indications would not even come close to describing the song.
C/A is pretty hard to distinguish from Am7, unless the A in the bass sounds really insignificant for some reason.
Hey, who put this intelligent theory discussion in the middle of my thread?!
Try to start a discussion on a simple topic, and Dopers will go pages arguing what “simple” means. That’s why I love this place.
Hmm, in terms of what I was calling for in the OP, yeah, the stuff being discussed is important: is the chord variant an essential part of the song’s hook? I am trying to come up with a non-theory way to describe a distinction. How about: are the variations being tossed in as part of a “big stew” that is trying to stay centered on the main chord, or is the chord variation “moving” the focus of the sound, so it feels like a chord change?
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And I was not thinking about the vocal line at all. Just chords. So this discussion is unpacking the difference between a song that is really trying to embrace its I-IV nature, vs. a song that you’d swear has many chords because of what happens within and on top of the two-chord (not necessarily I-IV).
Regarding the main topic, I think this is a One-Chorder: War, Low Rider: War - Low Rider - YouTube lordy what a great song. Lots going on, but I never hear the central groove change.
Didn’t James Brown (or was it George Clinton?) audition a guitarist (or was it a keyboardist?) thus?:
“Can you play a D seventh sus 9 chord?”
“Of course.”
“Yeah, but can you play it for forty-five minutes?”
Me too 
Totally. I guess it’s all what you want out of your analysis. As WordMan says: “So this discussion is unpacking the difference between a song that is really trying to embrace its I-IV nature, vs. a song that you’d swear has many chords because of what happens within and on top of the two-chord (not necessarily I-IV).”
There are times when it’s useful to identify that Eleanor Rigby is just two chords, but there are also times when that kind of analysis fails to communicate essential information about a song or progression.
And there are times when it’s just important to shut up and listen :).
I agree that it wouldn’t, but it still wouldn’t change the fact that it’s a one-chord (or whatever) song, at least not in my eyes. If the instrument is playing a G5 but the vocal is alternating between a B and a Bb, it’s still a song with one chord, a G5.
But yes, you can also over-analyze these things, and sometimes it’s better just to shut up and play the tune.
I just find it amusing that the one time I decide not to be nitpicky and technical about things of music theory nature, there’s like three other posters wanting to be nitpicky and technical.
At any rate, I take the more simple view of C and Em, with a note that there’s a chromatically descending line from the minor seventh to the fifth of Em thrown in the chorus. I prefer to think of it as a countermelody of some sort. Or like I said, just a line cliche to me. You can complicate the naming if you want–personally, I don’t like doing so.
At any rate, that’s the last I want to say about it. There’s obviously philosophical differences about how we interpret “what defines a chord as being different from another chord”? I used to have a very nitpicky interpretation, but, I dunno, maybe I just got old and listened to too much modal jazz or something and now I blur boundaries much more.
I play a lot of bluegrass/oldtime/Americana. The “standard” song has 3 chords, 1/4/5. But there are quite a few that have only 2. Last Sat we played a gig that included 3 2 chord songs:Crazy Heart; and 2 we play as a medley Julia Delaney and Sally in the Garden.
I disagree, it goes to the V chord to end each verse. If that’s a two-chord song, then so is every twelve-bar blues.
AH, yes, that unambiguously, by whatever definition we’re using, has another chord in it. 95% of the song is the i-IV vamp, but it all resolves to a V in “this can’t go ON…” that sends us back to the i.
As a bassist, but also guitarist, this is definitely true.
I view the under-utilized Major 6th chord as essentially a discrete chord, being an inversion of the minor chord a fourth below, but without the bass note. If the bassist plays the bass note as the root of the minor chord, it totally changes everything. But even just the guitarist can change it. Even just a vocal sustain, like the Beach Boys, of the sixth (or seventh) of a major chord can radically influence the overall sound.
As the bassist, I have control over any major chord that the rest of a band is playing. If I play a groove on the seventh, high up on the fretboard, the song takes on a different feel. If I play the seventh of a major chord as a low ostinato, like on the lower E string, that same major chord will sound menacing, as it essentially takes on a Locrian tonality by putting the seventh scale degree in the bass. I figured this out recently when I was playing bass along with John Mayer’s song No Such Thing. It’s a jangly upbeat major-seventh dominated song, but throw in a low D# (I experimented with detuning the E string a half step) on that open E string and suddenly the song turns into an unstable-sounding Locrian cacophony.
I think you mean a minor third below, right? Or am I misunderstanding? C6 (for example) has the same notes as Am7.
Good lord, we can’t have that. 
Seriously, that bassist POV makes sense. You are a throughline through the assembled chords.
Not to prolong this (and I always enjoy talking with/hearing from other musicians about stuff like this), but I’m glad you brought up jazz. It’s a context in which, most of the time, additions to the triad, and even passing chords themselves, aren’t really a fundamental part of the song. Take the tune ‘All of Me’. Opens with a C, and the second chord is an E7. But I (and others) often throw in a B-7b5 before the E7. Does that chord “count”? It’s definitely different from the E7, but it’s also kind of just adding color around the V of vi.
Just to add another non-musician perspective: I don’t notice chords, and they often don’t make sense to me. I mostly listen to the melody, the lyrics, sometimes the vocal harmony, and the rhythm is also important. I’d never think of Eleanor Rigby as a simple song because of the lyrics, and the violins, especially the short, sharp violin bits under Paul’s smooth singing.
I keep thinking about this question, and I’m not sure how I’d answer it. It’s kind of both yes and no to me, mostly yes, I think. For purposes of memorization, I would only think of the C and E7. But for playing with other people, you do kinda gotta clue them in that you’re thinkin Bm7b5 there. So far as I can tell, it’s basically functioning as a ii of vi going into a V of vi there, so it really is a different chord functionally. Then again, it’s not a necessary chord, and is, like you say, just adding color, as many other chord substitutions there would do.But I’m getting a headache thinking about it.
I mean, part of me is also thinking of like when you comp blues. You’re playing over, say, in the key of C, C7 the whole time, but you’re throwing in sixth chords, chords that look like F/C, stuff that looks like 13#9s, etc. in there, but I just think of it all as C7, or over the V chord (G7 in our key of C here), I like doing New Orleans-style licks where you play a C major arpeggio type of thing over it, but I just think of that as a V7 chord rather than, I dunno, C major over G7.
I think, though, that in the Bm7b5 example you gave, there’s a bit more going on there, so I’d probably box into the category of “different chord.”