It’s hard to know what the musicians you’re playing with are thinking. Consider what you have to go on. First and foremost you have the sounds they make. Though some try, musicians can’t ever hide behind their sounds because their sounds reveal them—they give voice to their sound-producing capabilities and limits. Presumably, a musician’s sounds offer a good idea of what they’re thinking in the moment. But hold on: does one’s sound-making necessarily reveal one’s thinking? As with other performative arts (e.g. dance, acting, even some kinds of writing), a musician’s playing can sometimes be an empty spectacle built upon a learned repertoire of tried and true gestures that have worked in the past and you know what, maybe they’ll work right now. I’ve watched other musicians play the exact same phrases night after night, and I’ve done the same. What were they—and what was I—thinking? Were we thinking about the music or thinking about something else and letting our muscle memory take over, or some ratio of the two? It’s hard to know. When I play I’m usually thinking about the music and many other things simultaneously. Maybe music playing music encourages this experience of omni-thinking?
Another way to know what another musician is thinking is by watching them interact with you–or not. Sometimes you exchange glances and smiles at certain points, like when members of a string quartet hit the downbeat together, or pass back and forth those mutual head nods to begin or end a phrase. I’ve actually found myself nodding my head even when the musician across from me is never looking my way, which makes my nodding a kind of acknowledgment of a relationship that isn’t (but might have been) in an ideal world.
Trying to understand what other musicians are thinking brings us to two further points. The first relates to what John Cage once said about why he didn’t like improvising: he thought that when musicians improvise they play what they already know, and so improvising by definition can’t break new ground the way rolling dice or using the Chinese I-Ching to generate random musical decisions can. Cage’s point showed what appeared to be a distrust of musicians actually saying something and thinking through the performative moment unless it was constrained—under a kind of prior meta-control—by chance or other set-in-motion procedures. But contra Cage, isn’t one of the joys of music hearing how someone thinks in the moment, and how they think through moments? This brings me a second perhaps obvious point, which is that sounds on their own don’t think. No matter how inherently interesting a sound appears to be, its power derives from how it manifests human thinking by relating to other sounds and changing itself over time. It’s no wonder that what makes music making social—relating to others and continual evolution— is the mark of an interesting musician too.