It is often said that music communicates or expresses emotion.
There is definitely something emotional about music.
But, I would like to propose an alternative hypothesis about the meaning of music, and what it is that music communicates, or expresses.
I propose that music is not primarily about the emotion.
I propose that what music is actually expressing, what it is in some sense telling us, is the existence of newly revealed information, where that information has emotional significance.
The music does not tell us what the information actually is.
It only tells us that the information exists, that it has been recently revealed, and that it has emotional significance.
Once upon a time (maybe two million years ago), the ancestor of music - protomusic - pragmatically communicated the existence of newly revealed information with emotional significance.
This prehistoric system of communication preceded the evolution of spoken word-based language as we know it.
Actually, protomusic not only preceded the evolution of spoken word-based language, it also enabled the evolution of word-based language.
Eventually the word-based language became so complex and sophisticated that it completely replaced the protomusical system of communication.
Where once protomusic asserted the existence of newly revealed information with emotional significance, complex word-based language could tell you what the information was, and, if required, could explain what significance the information had. (And of course it could be used to communicate information that did not have any immediate emotional significance.)
Protomusic ceased to be a pragmatic system of communication, but, somehow, it pivoted, and it turned into something else.
It turned into a motivation for human imagination.
Instead of communicating the existence of newly revealed information with emotional significance, it expressed the existence of newly revealed information with emotional significance.
When protomusic communicated the existence of new information, it was up to listeners to find out (if they could) what that information was.
But music did not communicate, instead it expressed. Music expressed the existence of new information, regardless of whether or not such information actually existed.
With music, it was entirely up to the listener to imagine what that information might be.
Of course sometimes the music is accompanied by other content that suggests to us what that information might be, whether it be the meaning of song lyrics, or the action in a movie where the music is the score.
But, when no suggestions are provided, then it is entirely up to the listener to imagine something that is consistent with the intensity and emotional tone of the music.
For more details about this hypothesis, see The Revelation Hypothesis, and other recent articles in my "What is Music?" blog.
I strongly agree with the idea that music indicates the existence of information. But I think it's because music is a *side effect* of our information-seeking instincts. The emotion is another symptom of our reaction to certain patterns of information.
It's hard for me to believe any form of music was ever pragmatic, when we already communicate emotion so efficiently with our voices (even without words). Pre-language emotional communication is the scream of a tribe member, the cry of a baby; it's body language and the tone of your voice. Laughter, gasps of awe, sighs, and a million other verbal sounds "pragmatically communicate the existence of newly revealed information with emotional significance". Our very ability to detect the emotion in someone's voice - which is quite sophisticated - doesn't seem related to music, but fills the exact role you hypothesize that protomusic did.
The ultimate meaninglessness of music makes it very hard to imagine it as being useful; it seems like the moment it becomes useful, it's no longer strictly musical. The moment a sound contains information relevant to a goal, it's language. And when you imagine the meaning of music, what you're really doing is adding a story to the music. The story that you imagine isn't music, although they obviously complement each other strongly.