Thanks

It is worth noting that ‘sound-space’ is, in certain respects at least, much simpler than ‘colour-space’. It seems that even if there were insoluble problems in the case of colour, two people a and b could agree in all their judgements about the pitch of sounds although a heard everything five tones higher than b (that is, intuitively, if a could per impossibile hear middle C ‘through b’s ears’, a would call it ‘G above middle C’). Notice that this could be so even if both a and b had perfect pitch—the ability, that is, to state the pitch of any note just on hearing it. — Galen Strawson

Cool comparison.

Actually, the scenario depends on a and b having perfect pitch, in the sense of absolute or non-relational pitch sensitivity or recognition. Otherwise, the alleged intuition,

that it could just be a simple unknowable fact that a’s and b’s overall experiences of sounds were five tones apart — Galen Strawson

would be hard to credit. Most of us are oblivious to the absolute pitch of sounds, and don't hear them to be (e.g.) numbers of pitch-steps higher or lower than others, except in context: relationally, indexically. For most of us there couldn't be a musical equivalent to, "ah, I see that your internal post box images are the colour of my internal banana images": at least not a scenario that is equivalent in the way Strawson wants to examine. Unlike a, we can't conceivably "hear middle C through b’s ears" because we can't recognise a middle C at all. (Me learning.) It's as though we aren't able to paint, nor later identify, our post boxes as red, but only as, possibly, redder than a (possibly green) banana we happen to have with us. If (and then I was going to say "we" but I'm too aspirational now) ordinary mortals have internal pitch sensations they don't map at all to non-relational values of sound frequency.

We might seek an analogy between relative (relational) pitch and visual colour differences or contrasts. That's a fascinating prospect, despite an obvious disanalogy: we can't begin to identify or compare 'intervals' of colour. And we can only begin, with scant hope of consensus, to even order colours. Without, that is, the intervention of a psychologist inferring from patterns in our failures to discriminate and order. But with pitch we can, unaided, form interval-based orderings (tunes) that translate recognisably to different positions on a scale (play in different keys).

A better parallel with colour differences and contrasts is, perhaps, pitch interval differences and contrasts. Since the better parallel with colours is pitch intervals. The steps on a musical scale may be conceived as displacements from a home or key pitch. Which isn't to deny the perceptibility of their displacements from other steps as well (perhaps encouraged by the theoretical influence of equal temperament?). But is merely to make it plausible to compare the scale-steps, so conceived, with colours. Scale : rainbow.

But all of the comparisons here, true or mistaken, involve what strikes me as a crucial relationship: an interaction between relational and non-relational clues to identification of stimuli; the tension between atoms and whole; between trusting wavelength and trusting context. Bleeding into the identity of a colour: its barely distinguishable relations with and position relative to others. Bleeding into judgements of higher and lower pitch: the haziest sense of interval magnitude.

Maybe "tension" and "bleeding" are metaphorical enough to, if warranted, explain belief in the occult: in "what-it's-like-ness", "internal sensation", "subjective experience", etc. Then people (e.g. ) would be right to connect these things to murky or hidden associations: with other colours, as well as variously coloured things. Belief in a "content", "quality", "character", "experience" etc. of seeing a coloured patch might be some kind of understandable confusion about the interaction of relational and non-relational clues to its identity.