(1) What philosophical issues are involved in music?
(2) What positions on those issues were taken by pre-Epicurean / non-Epicurean Greek philosophers?
I found some issues in the following :
Still on this issue of the nature of music, it has to be pointed out that in the passage of the pseudo-Aristotelian Problems to which reference was made above it is admitted that not everything in musical sounds imitates character (ethos), for this applies to the arrangement of higher and lower sounds but not to their mixture (mixis) ; further, consonance (sumphonia) is expressly said to have no moral character. Probably mixture is supposed to contribute to consonance, in any case that the beauty which music presents and the pleasure it procures depends on these aspects. There are thus two dimensions of music, one which has to do with character and the other which has not, but which both possess aesthetic significance. Plato must have been aware of this fact, for, as we have already seen, in Republic IV, in a context in which he talks of music, he is induced to point out that certain qualities, such as gracefulness and gracelessness, are also to be found in the products of painting, of architecture, of weaving, and so forth (cf. 400e ff.). In the case of these disciplines in fact certain formal qualities of beauty, such as symmetry, which have not to do with character, play an important role (as we shall see below, ch. 29), but there must be a point of contact between them and music, which lies precisely in the fact that certain formal qualities of beauty are also to be found in music. It has to be admitted, however, that in the passage I am considering Plato is not relying on any such neat distinction, for he is willing to talk of moral traits, such as the negative ones of evil disposition and illiberality, and of images of evil (eikones kakias) also in the case of the products of those other arts.
Finally, it has to be stressed that the doctrine which is present in the dialogues also finds a significant expression in a passage of the Timaeus in which, after having considered the usefulness of the sense of sight, he considers the usefulness of the sense of hearing and that of voice. The passage deserves to be quoted in full :“For not only was speech (logos) designed for this same purpose, to which it contributes in the largest measure, but also that part of music (mousiké) that is serviceable with respect to the hearing of sound16 is given to us for the sake of harmony. Harmony, having motions akin (sungeneis) to the revolutions of the soul within us, has been given by the Muses to him whose dealings with them is guided by intelligence, not for irrational pleasure (hedone alogos), which appears now to be its utility, but as an ally against the disharmony that has come into the revolution of the soul, to bring it into order and consonance (sumphonia) with itself. Rhythm, again, was given us from the same entities as a help to the same intent, for in most of us our condition is lacking in measure and poor in grace.” (47c6-e2). The parallel he draws here with sight lies in the fact that the observation of the ordered revolutions in the heavens, which are a manifestation of (cosmic) intelligence, is of help in bringing order in the motions of thought inside us (cf. 47b). The idea that there are revolutions in the souls that are similar to those of the celestial bodies was introduced in a former part of the dialogue. It implies that the same harmony is present in the heavens and in our soul, when this reproduces in itself, by imitation (mimoumenoi, 47c3), the order of the heavens. (The same suggestion, in the simplified form that there is an imitation [mimesis] of the divine harmony in mortal movements, comes back in 80b.)
Music is thus seen as an expression of this cosmic attunement and concord. This position is close to Pythagoreanism and goes beyond the idea that harmonies and rhythms are imitations of movements in our soul.(The Pythagoreans notoriously asserted that there is a celestial music - what will be called, anachronistically, the music of the spheres - that is inaudible to most men. Plato was certainly familiar with this view and, though he probably did not take it seriously, it remains significant that he supposed that the world-soul is divided into harmonic intervals and made the celestial movements depend on this ‘musical’ structure, cf. Timaeus, 35b ff., together with the commentary by F.M. Cornford, Plato’s Cosmology, London 1937, pp. 66-72.17) 40
On the other hand, there remains the idea that there is an affinity (sungeneia) between them and those in our soul, for only in this way can music exercise the effect of introducing order in the movements in our soul. This is seen as the aim that is to be pursued by humanly made music. Presumably pleasure is to be rejected as an independent (alternative) aim of music (as of the other beautiful arts) and as ‘irrational’, but not when it arises from an accord between the harmony in the musical sounds and that of the ‘revolutions’ in the soul. In fact, when coming back to this motif, in 80b, Plato is not excluding any pleasant reaction to the reception of harmony in one’s soul, but keeps distinct pleasure (hedoné) as what is felt by silly people from the good cheer (euphrosune) which is felt by the intelligent ones. As to education, this must be meant to realize this sort of accord. (Paideia is not mentioned in the Timaeus in this connection, but later on, in considering vice as ignorance resulting from lack of paideia, cfr. 86d-e, and in presenting paideia itself as the remedy for this situation in 87b. Gymnastics, music and philosophy are clearly taken as parts of paideia in 88c and said to contribute to a condition of harmony and proportion or equilibrium between body and soul.)
source : https://journals.openedition.org/etudesplatoniciennes/997