What is jazz theory for?

Jazz music theory certainly isn’t the most important thing to play jazz music. Most of the times it even doesn’t help playing since you don’t have enough time to think theory when you are sight reading the chart on stage.

What then will help improvising jazz music?

In a Tony Wiliams interview I read a long time ago, he was talking about how he learned to play.  He latterly copied giants such as Max Roach, Art Blakey, Philly Joe Jones, and a few others one by one.  He copied down to how they walk, ware exact the same hat, smoke the exact same cigar (he was 10, however).  By the time he copied the 5th drummer on the list, he realized he earned his own style.

Tony Williams’ way is the easiest in my opinion. But in my case, Miles is my God and I even don’t try to study him but just warship him instead. When I started to get serious about studying jazz, I listened to Miles’ 1964 Lincoln Center recordings for one year, over and over, tried to memorize everything what’s on that two disk set.

I then had quite a few idols, not at once, but one by one. For performance, there were Wes Montgomery, George Garzone, Pat Metheny and Michael Brecker. I transcribed them in my early days a lot. For composition, George Russell, Thad Jones and György Ligeti.

Would theory help?

Unless you are a genius and can play absolutely anything by ear, not to mention photographic memory to memorize everything in one path as Wes Montgomery did, you need certain theoretical skills.

• You must be able to see all the chord tones up in the air.
  They are the safe note to play — except root when Major 7th chord.
  
• You must be able to see the 3rd and the 7th of the chord instantly.  They are, especially the 3rd is, the note that characterize the chord.
• You must be able to tell if the second note of the scale is Tension 9th or scale note 2.
  How many times do you need to think about this? The answer is only when soloing on a minor chord .
  

With this information above, you construct your improvised melody with Root, 2nd/9th, 3rd, 5th, and 7th, A Coltrane approach . If you are grooving, you are all set.

What is jazz theory for?

Deep understanding of jazz theory is very much needed once you wish to write your own piece. This is not like classical music which others just read notes you wrote. A composition that is badly notated with improper theoretical background only makes other players play your music badly.