Though my two favorite topics -- music and language -- are fairly technical ones, I try to avoid writing about them in two much technical detail for two reasons:
1) I want people to enjoy reading this, and I don't want to alienate or bore anyone if I don't have to, and
2) I don't really know how. I'm largely self-taught in both subjects, which means I've picked up bits and pieces of the jargon, but I can't use them with confidence.
But now I want to write about something a bit technical. I will try to do so in a way that neither bores readers nor esposes my ignorance. Here goes.
A few weeks ago Bobby Lightfoot wrote a long rant about guitarist Carlos Santana. Me, I've never felt one way or the other about Santana -- he always seemed pleasant and innocuous, like most guitar virtuosos. I make an exception for Hendrix, but that's because he's a strong (and underappreciated) songwriter, not just an accomplished technician. In any case, Bobby Lightfoot characterizes Santana's playing as "pentatonic woodly-woodly" -- an apt description.
"Pentatonic" is a mode, that is, a subset of notes. If you think of the notes in the melody of "Oh Susannah" (or just about any Stephen Foster song), that's the pentatonic mode. Santana does spend a lot of his solos aimlessly wandering around the pentatonic scale. But when I first read this, I thought, "Well, pentatonic woodly-woodly is a darn sight better than blues woodly-woodly." Which is not to knock the blues, by any means -- just the mediocre musicians who use the blues as a crutch, because you can sound a lot more competent than you are if you stick to the blues, especially if you don't have an ear. Of course, this trick has its limitations, most significantly that it only works with songs that are in a blues mode. Nothing is quite as jarring as a song with pentatonic melody and harmonies with a blues solo plunked down in it, and yet you hear this fairly often. Indeed, musicians who affect faux-naif sensibilities sometimes do this intentionally, a prime example being the Velvet Underground -- if you know the guitar solo from "Pale Blue Eyes" then you know what I'm talking about.
It's a shame these modes don't mix happily, because they are the two most American modes. Some argue that the ubiquity of pentatonic music is the heritage of Scotch-Irish immigrants. That may be the case, tough I'm skeptical of attempts to demonstrate Scotch-Irish roots for American things. The heritage of the blues scale is also controversial. Of course it is African American in origin, but many seek to trace it to Africa, something else I'm skeptical of. The only element of the blues I've ever heard an African precedent for is guitar polyrhythm, which is fairly superficial, and is limited to early blues. But the blues scale never sounded particulary African to me. I think it is really an innovation of African-American culture. which I think makes it even cooler than if it were imported. Nevertheless, given that these two modes are so fundamentally American, you might expect them to combine more gracefully.
Why is this combination so jarring? I thought about it for a while, and the best answer I could come up with is that the dominant seventh in the blues scale (one of the most important notes in it) interferes with the sixth, which is crucial to the pentatonic. Earlier I thought it might have to do with the third of the blues scale, which is "blue" -- it exploits sliding and semitones to create an ambiguity between major and minor. But the third is not the problem, as I can prove.
The following is a field recording from 1926 in Darien, GA of W. M. Givens singing a spiritual called "Deep Down In My Heart."
Notice that it is strongly pentatonic, and yet the thirds are blue -- hear how he swings up to it on "everybody". Note furthermore that there is nothing remarkable about this -- it sounds prefectly natural. (While I'm at it, I can't help pointing out the strange vowels in the words "heart" and "brother.")
What could be more American than this? Pentatonic with a blue third. Ebony and Ivory. And now that I'm aware of this combination, I hear it everywhere, even in my own songs.