In Book VIII of his Politics, Aristotle talks about music: its role in ancient Greek education, its differences from the other arts, and its philosophical significance. This is not an in-depth exploration of the philosophy of music (what I wouldn't give for his lost work Περὶ Μουσικῆς), but more of a cursory glance. Yet through extrapolation we can tease out some meaning from his discussion.
Aristotle wonders why the ancients had legislated music (along with language and physical exercise) as one of the three primary areas of study for Greek youth, given that it is not especially useful (in the sense that physical exercise conduces to courage, or knowledge of the Greek language helps one succeed in community interactions). He notes that music is not merely pleasant but that it is one of the highest forms of leisure - a fitting adornment to the life of a free people. Yet this is not enough, for he also wonders whether music has some ethical purpose by prodding one to become a better person.
He concludes that this is indeed the case, for several reasons:
Aristotle does not elucidate the exact nature of the likeness. However, based on our knowledge of his writings on ethics and psychology we can make some informed guesses. In De Anima, Aristotle describes ψυχή or aliveness (usually translated "soul") as what gives overall form to the body, and in the Nicomachean Ethics he describes each ἀρετή (thriving or excellence of character) as a deliberate practice of good judgment, reasoned commitment, and planned activity resulting in a balance between extremes in a particular domain of human life. Just as ψυχή is the form or animating principle of the body, so ἦθος or character is the forming, directing, guiding influence over your bodily motions and emotions, your actions and reactions. In a similar way, perhaps rhythms, melodies, harmonies, and modes impose an order or balance on the emotional expressions of music by forming and shaping them in a way that is mindfully attuned to a certain state of character. Although ψυχή is not itself a harmony, it brings all the aspects of a living being into harmony so that the animal can achieve its innate goal or purpose (for humans, the goal of εὐδαιμονία); and music as aliveness and thought expressed through time achieves similar effects.
Furthermore, Aristotle holds that the best actions and states of character are not only good but also pursued for the sake of what is admirably appropriate (πρέπον) and beautifully right (καλός). For instance, he describes civic courage (defending one's community in battle out of a feeling of obligation or for avoidance of shame) as not quite true courage in comparison to courage acted upon because it is the beautifully right thing to do; similarly for generosity, friendship, and other excellences of character. Just as ethical beauty can be exhibited in a wide range of balanced and mindful actions and reactions (even in your manner of dying), so also music can be beautifully sad or joyous or poignant or powerful or even angry, and can beautifully represent many different states of character. This is why Aristotle thinks the beauty of music suits the best way of life; yet an Aristotelian philosophy of music would not countenance that which is merely pretty, the kind of music-box banality that sounds nice but has no depth or stature, but instead encourage the musical ambition (of scale, sublimity, virtuosity, excellence, and beauty) to match his conception of "greatness of soul" in ethics.
Finally, although Aristotle and the ancient Greeks in general believed that the life of a musician lacked a certain nobility (they thought all the arts were too mechanical), today we would see musical creativity as a form of θεωρία or inquiry because the composer or performer engages in a deep exploration of the possibilities of musical materials and tonal space. Indeed, I would argue that good musical judgment and good musical taste are instances of the Aristotelian intellectual virtues of phronesis and sophia, and thus that the pursuit of musical wisdom is one path toward philosophy as a way of life.
The foregoing is but the merest sketch and does not delve into the specifically musical aspects of a philosophy of music (melody, harmony, rhythm, modes, time, tone, texture, deliberate practice, improvisation, ornament, composition, performance, etc.); nor does it indicate how to apply these principles to a wide variety of musical styles and genres (even just in Western music that would include medieval, Renaissance, Baroque, classical, romantic, and modernist art music as well as jazz, blues, folk, rock, etc.). To expand this kernel of a idea into a worthwhile contribution to the philosophy of music, I would need to complete a great deal of research and reflection. Maybe I'll do that after I finish writing a book on Aristotle's ethics...
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