I've been willing to talking about this for a long time, but it always seemed like a foreboding task. It's not a complex argument, but it's difficult to deliver it the right way.
The topic of "Emotion" in music always baffled me, somehow. It might seem strange, since emotions are extremely intuitive, and everyone knows what they are. That's exactly the problem: everyone seems apt to talk about emotion in music, because they know emotions so well. But talking about emotions in PEOPLE is different from talking about emotions in music. "Emotions in people" are clear and intuitive because emotions are IN the people, they come from within them. Emotions are not IN music. Music has no emotions, they don't express emotions -- it's the ARTIST that uses music to express their emotion, if he wishes to. This line of reasoning may sound clear and obvious, but many, many people don't follow it.
Go out and see how many people talk about how "emotional" a particular song is. Go and read the opinions of who think someone's playing or singing is "emotional". I ask myself: how is a listener able to objectively detect that? That would imply that music can deliver distinct, unambiguous emotions by itself. So, that means we only need to find the correct combination of musical and sonic properties to deliver one specific emotion. That way, we effectively transform music into a language, free of ambiguity and obscurity. And... there are problems. Firstly, art doesn't have to be a form of one-way communication: it's not a lecture, not a lesson, it's not the artist telling the audience how it's supposed to react. Music, as well as any form of art, can be interpreted differently by different people, and in my opinion, THAT is what should be encouraged. The audience should fill in the gaps with their own perception, turning art into an almost interactive experience; yes, interactive, since the art "changes" as the audience changes their perception. So, making music an unambiguous language is an obstacle for that. Secondly, different cultures around the world have adopted different musical systems, which means that one musical piece would NOT be interpreted the same across those different cultures, even if the artist truly, really wanted that. So the "language" of music is a social construction; it is restrictive, alienated people outside that culture and diminishes the possibilities of innovation and originality. In short, it sucks.
Unfortunately, that's how music has been progressing since... well, forever. Certain combinations of chords and melodies are perceived as "emotional", and quickly they become clichés; tired, annoying, ineffective clichés. Is THAT what we want from music? Now you see why 20th century classical music sounds so "crazy"?
Oh, no, but I'm getting it wrong, right? Emotion in music does not come from certain notes or chords: it comes from the energy, the spontaneity, the "feeling" of the artist. Oh, well. Again, I could question how "energy" and "spontaneity" could be unambiguously detected by the listener, but actually I wouldn't have a very strong point. However, recorded music nowadays is NOT AT ALL what most people think it is. Any piece of music you hear nowadays most likely has been a product of painstaking, tiresome, cold and calculated studio work. Dozens of takes are recorded, lots of effects are applied, even complete takes are edited all the way to Hell and back, things are chopped, spliced together, and so on and on, to the point where there is hardly anything "spontaneous" going on. With that, it's hard to tell if an artist is truly "expressing" himself, because the bigger worry is with making the whole thing sound RIGHT. So, we have no way of telling whether one particular part of the performance is pure human emotion or pure fakery. The only way you can tell is by intuition. Either you know the artist well enough to recognise his habits and know what they mean, or you're most likely guessing.
And yet, even with all that effort going into making the recording sound "right", we enjoy those recordings. To us, it doesn't matter how many dozen edits there are, or how many dozen takes were recorded, or which instruments are playing in each track. Music, even almost completely drained of "spontaneity", is still enjoyable. How come?
The truth, as I see it, is: emotion is not in the music. Emotion comes from within YOURSELF. The music merely provokes you, and it's YOU who concocts those emotions. That's why music works differently in different people, to the point where certain pieces of music can cause wildly different effects and provoke radically different emotions in different people. And that, my friends, is one of the things I like THE MOST about music.
So, the next time you're talking about how "emotional" a song is, don't be surprised if I dismiss your opinion entirely -- it tells more about YOU, as a listener, than about the music, which is what I'm more concerned about.