The Important DIFFERENCE Between m7b5 And Half-Diminished 7 Chords

This is going to be controversial.

In fact I debated for a while if to make a video about this or not. I mean, what I'm about to say should be commonplace... but it's not.

I'm definitely taking the contrarian positions on this... so be it :)

So here's the story. There are two chords that behave in a different way and that they are even called in different ways... and yet everybody confuses them.

Worse than that... they even teach you that they are the same chord.

Even Wikipedia will tell you as much!

Hey, even *I* used to confuse them!!

Talk about the truth staring you in the face... they are called differently, they behave differently... and yet we were all thinking they were the same.

These two chords are the "half-diminished 7" and the "minor 7 flat 5".

And no, the explanation is not "they are the same chord, they are just called it differently in Jazz and in Classical harmony"

The explanation is: "they are two different chords, and for a good reason!"

(I can already hear the cries of protest to this last statement...)

So here we explain the real difference between "half-diminished 7" and "minor 7 flat 5", why everybody confuses them, and why it's important to NOT confuse them.

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[JohnnyCameo]

I travelled from Manchester to meet a friend in London.

He travelled from Paris to a destination he insisted on calling Londres.

“That’s OK”, I said. “Two different names for the same city.”

He shook his head sadly. “No. We started in different places and will return to different places. Therefore we are not now in the same city”

In the confusion thus created he left and I picked up the tab.

[MaggaraMarine]

I think the most important question here would be whether people actually use these terms this way. Because I have never heard of anyone making this distinction, and I haven't seen people using the m7b5 and half-diminished symbols in different ways - often people choose one or the other and use it for all chords of the same type, a bit like people either choose "maj7" or the triangle symbol. In the end, both "half-diminished" and "m7b5" are just two easier ways of referring to the chord that is actually called "diminished-minor 7th", similarly as full-diminished would be "diminished-diminished 7th" and dominant 7th would be "major-minor 7th". These are simply terms that people have come up with to make the 7th chord naming a bit simpler. It's easier to say (and distinguish between) "dominant", "major 7th" and "minor 7th" than "major-minor 7th", "major-major 7th" and "minor-minor 7th".

My point here is that these are just "spoken language" terms that have become somewhat standardized. They aren't really formal terms. I know that a counter argument to my post could be that "but those people are using the terms incorrectly", but I disagree - these labels aren't "formal" and they aren't 100% standardized either. We are basically talking about the "spoken language" of musicians.

Both of these chords - the vii in major key and the ii in minor key - are derived from the same degrees of the diatonic scale. These are the scale degrees 7 2 4 6 of the major scale and the scale degrees 2 4 (b)6 1 of the minor scale (for example notes B D F A in C major and A minor). It is exactly the same chord and has the same origin.

Also, the use of half-diminished chords predates dominant 9th chords - they can't be derived from dominant 9th chords, because half-diminished chords were used before dominant 9th chords were a thing. It's simply the diatonic VII chord in the major key. Similarly, the IIm7b5 isn't actually derived by lowering the 5th of a normal IIm7 chord. It's simply the diatonic II chord in the minor key.

I think all of this stems from the common misunderstanding that "diminished" always means "substitute for dominant". That's not the only use for diminished chords. Classical musicians have been using the diminished triad as the ii chord in a minor key for ages (and in classical music, this is pretty much as common as using the diminished chord as the vii chord). And if you look at full-diminished chords, their only function isn't a "rootless substitute for 7b9" - you have common-tone diminished chords and chromatic passing diminished chords, and they are all full-diminished chords, even though they are functioning in completely different ways.

Actually, if you look at classical music, the half-diminished chord is much more likely to be used as a ii chord than as a vii chord. Going vii half-diminished I is fairly rare. Going ii half-diminished V is done all the time. The ii chord is often simply inverted (1st inversion is most common, 2nd inversion is fairly common). The third inversion is used over tonic pedal points where you usually alternate between the i and ii chords over 1st scale degree in bass.

Even in major keys, the most common use of the vii half diminished chord is to continue to the chord a fifth below. It's mostly used in sequences - IV vii iii vi ii V I (and yes, even in classical music all of these chords may be 7th chords, except maybe for the I in the end). The full sequence is rarer in major keys, though - it's much more common in minor keys.

I do understand where the name of m7b5 comes from, though - jazz musicians probably started using the term because IIm7b5 V7 I and IIm7 V7 I are so similar.

But just because the chord has two (or more) different uses doesn't mean we should name it in a different way based on that use. Chord symbols aren't functional symbols. They simply tell you what notes to play. We don't do this with any other chord. We don't use a different symbol for tritone subs or backdoor dominants, or non-functional dominants, even though those chords are used way differently than regular dominant 7th chords (and we need to remember that the term "dominant" comes from the fact that it's built on the dominant - the 5th degree of the scale). And similarly, diminished 7th chords that have different functions don't have different names either. If we don't do it with any other chord, why should we do it with half-diminished chords?

Actually, jazz chord symbols often have incorrect enharmonics any way (which BTW I don't have a problem with - often these "incorrect enharmonics" are used to make the chord symbols easier to read), so I really don't see why there would need to be a distinction between the same chord that functions in a different way. Functional analysis is better done with roman numerals than chord symbols. Chord symbols are simply a shorthand that makes communicating collections of notes much faster than having to write all of the notes out on sheet music.

[SilloniusAeldarian]

I love how he always talks like he was just beginner so he can interact with most of us, while it's actually a deep talk.

[Nicky-T]

This all fell into place when you showed how the resolutions worked in jazz as opposed to classical. Good thinking.

[tommy]

Ciao Tommaso! I think we can see the main difference between these two chords when we expand them. While the m7b5 should maintain regular intervals as second grade of the major scale(except for the 5th, which of course we altered), the half-diminished should maintain the classic "locrian-sounding" intervals.
Therefore I would expect the m7b5 to have a major 2 as an expansion, while I think the half-diminished should have a minor 2, following the intervals of a locrian scale.
(I took the 2nd as an example, but it's also the case with the 4th and 6th)
m7b5: R-2-b3-4-b5-6-b7
h.dim.:R-b2-b3-b4-b5-b6-b7
Did I explain myself well?🤣

[krickrack]

It's a bit like some words are spelled exactly the same but have completly different meaning and are used in completly different contexts and someone says "But it's the same word!"... no it's not.

[PlayTheGuitarra]

I get your point but both names are used interchanged all the time... If you look at Berklee books they teach the seventh grade of the major scale as a -7b5 and this one resolves up by a semitone, I don't think those guys are wrong, it's just two ways of calling the same thing, I think the title of this vídeo could have been "The two functions and names of the same chord"... In fact I believe that actually speaking the name -7b5 is nonsense because if a minor chord has a flat 5 then it's no longer a minor chord, since a minor chord is Root, b3, P5, if You don't have a perfect fifth then it's no longer a minor chord strictly speaking but it's just one of those things people Say to communicate and I believe that in the jazz context they came with that name as an easy way to explain someone how to play a half-diminished chord easily, like they said to a pianist "Play a minor 7 chord, now lower the 5th a semitone" and that was easier than saying "Play a half-diminished chord" or explaining to that person the intervalic structure of the chord 🤣🤣😅🤷🏻‍♂️🤭

[ThiagoNunnes]

Sorry, but only in this situation you are putting different names for different functions. It doesn’t make sense. They are the same chord. Dm7(b5) can have 2 functions. Simple like that. And the name half diminished comes from the laziness to correctly name the chord from VII.

[cofftpsyago]

I’ve recently noticed that those chords are functioning differently but I couldn’t completely organise my thoughts about it. And now this video shows up just like a miracle. Thank you !

[alsatusmdA]

1. Classical music also usually uses diminished chords in first inversion in order to avoid the tritone they put above the bass in “root” position so VII° looks like it is supposed to be a substitution for IIm, which is another premise for resolving it by step.
2. So you can ostensibly resolve IIm7b5 down a minor third to avoid playing a major third above the bass in a minor key, e. g. Dm7b5 Bø~B°7 Cm? Or resolve bVII9 down a minor third to avoid playing a minor third above the bass in a major key, e. g. Bb9 G7 C?

[michaelthomas]

Finally learning this -- wonderful explanation. I'm having more trouble getting to the min7(b5) than resolving from it, particularly coming from the IV when I'm substituting min7(b5) for the ii.

Thanks for the great education!

[yinchenxu]

As a classical musician i tend to treat them as different functions of the same half-diminished chord, because the first example C minor is the relative minor of the second example Eb major, and they share the chord of Dø7 (or Dm7b5)

[ericprimeau]

Thank you for providing a very good explanation of context. The voice leading is important if you have a tonal center. Your mastery of harmony continues to amaze me! Thanks for putting up all these useful videos!

[ralfpisters]

Classical theorist here. There is no truth to the claim (around 06:50) that this chord is more often used as a dominant (called "half diminished" here) than as a subdominant ("m7b5") in classical music. In classical music, just like in jazz, this chord is far more common on the IInd degree than it is on the VIIth. Just pick up any classical piece written in a minor key and you will see the chord all over the place on II. If, on the other hand, you pick up a classical piece in a major key, you are going to be hard pressed finding the chord used on VII anywhere at all.

[michalmikolajmaslowski]

Excellent, thank you! Context & intent are everything and this proves it.

[brianfraneysr.]

Jazz musicians refer to musical “vocabulary”, and just as you describe this chord, there are many spoken words spelled and pronounced the same but have completely different meanings which depend on their placement in a sentence and/or the other words nearby. But the word is spelled the same no matter how it is used. Likewise, same chord different “meaning”.

[tahsinthoughts]

I am just learning m7b5 shapes this week and came across this question myself. What a timely video! Thanks!

[lr]

at first, i was surprised, then after watching the video, it makes sense... furthermore now it is clear to me where the name half-diminished comes from... thank you

[donngoodside]

All of your 'Video's, are concise, and easily understood, even to non-musicians .Thank You

[waughannauron]

I have a feeling that naming the chord isn't important. The name really doesn't tell me if it is ii chord in minor key with subdominant function or vii chord in major key with dominant function. That's clearly the problem of context, but that's not the reason why I should name the chord differently. I'd rather use m7/b5 symbol in any context simply because it instantly says which tones there are.