These are the first ten definitions from dictionary.com, I did not include the last few because they along some others are irrelevant.
art/ɑrt/ Show Spelled[ahrt]
1. the quality, production, expression, or realm, according to aesthetic principles, of what is beautiful, appealing, or of more than ordinary significance.
2. the class of objects subject to aesthetic criteria; works of art collectively, as paintings, sculptures, or drawings: a museum of art; an art collection.
3. a field, genre, or category of art: Dance is an art.
4. the fine arts collectively, often excluding architecture: art and architecture.
5. any field using the skills or techniques of art: advertising art; industrial art.
6. (in printed matter) illustrative or decorative material: Is there any art with the copy for this story?
7. the principles or methods governing any craft or branch of learning: the art of baking; the art of selling.
8. the craft or trade using these principles or methods.
9. skill in conducting any human activity: a master at the art of conversation.
10. a branch of learning or university study, esp. one of the fine arts or the humanities, as music, philosophy, or literature.
The first definition is exactly what I want to know, according to aesthetic principles of what is beautiful. Does this mean we can quantify in technical terms, What is Music? Or does this mean, if everything is in time, in tune, with a good sound, and some phrasing the performance is elevated to Art? These things are aesthetic principles in music, does the technique define the Art? Or is there something more? Look at the seventh and eighth definitions, they are both about craft(technique).
The last few days I have the opportunity to discuss this with Marc Williams and Will Timmons. They both added a third person that could perceive and react to the music. Now, this could be the musician involved with the music also, because of course they are hearing the music. Going along with the enlightenment thinking this makes sense. The perception of beauty taking place where perceptions are processed, within the self. Now does this mean we should just stop searching for this answer? If beauty is processed within an individual how can we possibly quantify artful playing?
I don't think so. If we can figure out what is art, we can achieve it more often. This quest is worthwhile. In giving specific examples and playing passages we can discern more of musical performance. But this usually manifests itself with taking about direction, phrasing, and inflection. We could does this for the entire repertoire, the time implications are insane, and if we did we could simply program a robot to play for us. I think the best thing is experience a musical performance so individuals can apply the experience to other music. So listen and perform as much as you can, hopefully technique does not get in the way and every performance can be closer to musical.