1. Direction and magnitude — the engineering/mathematically savvy will recognise vectors here. I don’t want to explain vectors here, and prefer to discuss the direction/distance issue separately.
2. A direction defined by what? This question is especially relevant given that I am talking about the direction of other things such as ansin, arguing that ansin has a different direction relative to each eye. So what determines that each eye has a different direction?
I think anything will do, even each eye, with the condition that, if the eyes have different directions relative to at least one other thing, then they have different directions; they may lie in the same direction, however, relative to other things, and depending on different ways of calculating coordinates in space, e.g., lying in different directions under straight Newtonian coordinates, but parallel under curved space.
It’s like with motion: if two bodies have different speeds relative to something, This makes direction relative, conventional and/or arbitrary, depending on how one picks out or chooses to work with ‘anything else’.
However, one might want a general answer. So, perhaps ‘anything’ could for example refer to everything — and one could say that the direction of the eye is relative to what it is relative to everything. To make that coherent, because many things face in different directions relative to each other, either this ‘relative to everything’ would have to be:
(a) A whole range of values — making the eyes ‘direction’ a set of varying directions.
If the range of values is all possible values, then that set includes all directions. So, in which direction is my left eye facing? Answer: any direction whatsoever (but depending on what one is determining it from).
(b) A calculation (an average, mean, etc.) from these values.
(c) Relative to everything within some domain of things, e.g., electrons in the Earth’s magnetic field.
One could try this: face the direction in which they move (if one wants to anthropomorphise them, and not only that, but to a normal human — no running backwards). Then, a direction ‘relative to everything’ is restrictively defined as being relative to a coordinate system determined by the average of those electron’s velocities (getting Magnetic North). useful for certain contexts.
But this is not the direction which one is forced to accept in all contexts. If I prefer to define direction according to something other than this average, I don’t see why I should also consider this direction as well.
For example, say I want to define direction relative to the path light takes between Betelgeuse and my eye when that light hit my eye one night late last autumn. I say what’s left or right, above or below, in front and behind. That looks just fine. To avoid questions of relativity, one might argue for a non-relative, or non-arbitrary and non-conventional direction to which one can then define the direction of each. But, unlike with time, I don’t know anyone who thinks there is such a direction in space (do you?).
3. I refer to the set of conventionally-identified organs related to one sense as just one organ for that sense. E.g., the sense organ for sight is the set of eyes; it is not each eye (which we conventionally identify as a single organ). Why?
I think the common reasons for picking out each organ is relative to the picker’s discriminatory limits. They identify two sense organs for sight because the visual system on the surface of the body, on the human interactive scale, seems to have two parts — the eyes. But how it seems to someone is no reason on its own to think that the visual system is comprised of one, two or an multiple of sense organs.
It may seem that way because of limits of the perceiver only if how it seems to someone is how it is are we so justified (and then trivially, since in such a reason we build in ‘how it is’ to justify ‘how it is’). Putting aside how they seem to others, it’s ambiguous if each is:
(a) An entire sense organ of its own. For example, because each eye is somewhat free to move on its own. If sense organs are identified as capable of independent movement, then maybe you can say that each is a separate organ.
(b) A set of sense organs or part of a larger sense-organ. Call each eye a very large set of sensory organs — a light detectors.