Paulibus said:
Spinors have been a sophisticated feature of elementary addition for more than 80 years now. Is the operation of constrained and non-planar addition on which spinors are based a discovered and eternal Platonic truth? Or is it an evolved description of change in special circumstances that we have invented to rationalise for human purposes our probably specist perception of reality?
Again, this illustrates the point I was trying to make. Maths is a formal machinery for the construction of constraints.
So out in the real world, a triangle, a path, a channel, an object, a whatever, comes to exist as a matter of top-down constraints. There is some source of potential, some unbound, undetermined, degrees of freedom. And things happen to constrain those freedoms to have a particular form.
Then in our heads, maths is a way of modelling states of constraint via bottom-up construction. We can define a triangle, a path, etc, in terms of step-by-step operations. So we can describe what is out there in the real world using a language - the construction of meaningful statements using words and rules.
Out in the world, a triangle would just happen as an emergent feature of reality. But humans create a recipe for making such things happen.
Crucially, there is nothing special about this kind of construction of constraints via a "language". It is the secret of life. That's what genes do too. Out in the world, a complex protein might form by accident because - like a triangle - you just happen to have an unlikely combination of contraints impinge on a locale. But genes are a mechanism for constructing the set of environmental contraints that will produce such a molecule with a high degree of inevitability.
Actual language - words and grammar - do the same thing at a idealistic level. Left to itself, a large brained animal might happen to form some kind of idea. The constraints that happen to impinge on a mind at some point might create a certain firm impression (such as I see a cat). But language can be used to construct such states of mental constraint with a high degree of inevitability.
Then maths is just a further development of this general epistemic trick. The kind of objects~operations that maths talks about are so generalised, so abstract, that they can be used to construct constraints in the most universal possible fashion.
Genes talk about very concrete stuff - the constraints that regulate metabolic processes. Langauge mostly talks about concrete stuff too - this cat, that dog. The material and the formal aspects of "what exists out there" are still entangled. Though language of course can progress to high abstraction, as in philosophy (so paving the way for science and maths). The particular, local, material aspects of "what is" can be generalised away to leave only the Cheshire cat's grin of the notion of the formal limits that might bound that materiality. So language can come up with pure ideas such as the good, the one, the discrete, the infinite.
Maths then deals only in purified formal notions. It wants to leave materiality completely behind (to the point where mathematicians can despise intuitive mental imagery or illustrations cluttering up textbooks). If materiality is needed, it can be put back in by measurement. One what? Well, one apple, or one cat, or whatever. But leave the messing around with measurement to science.
So discovered or invented? Again, this question is being posed as a forced choice, a case of either/or, when really maths has aspects of both.
What maths is discovering/inventing is the formal half of reality - the fact that reality is the product of constraints on material potential, and so how to (re)construct those constraints.
So the Platonic forms are "out there" in that the potential to materially construct them really exists.
But they are also not "out there" because in our heads they are idealised descriptions. We imagine a realm of perfect triangles and true infinities that are beyond material actualisation (because they are the limit description on acts of material construction).
On the whole, maths still seems more invented than discovered because it does not relate so obviously to the world we directly experience. If we are looking for naturally-occurring patterns about us, we are far more likely to see vortexes and fractals than triangles and infinities. This is because the world is dissipatively material. The constraints that form its patterns arise in way that maths only recently began to model.
But as I say, the early maths - the initial geometric breakthrough - was so striking because it found a way to objectify the symmetry-breakings that must have occurred right at the start of the universe. A triangle is a pretty unnatural pattern to come across as a product of material dissipative structure. But it does reveal the existence of flat Euclidean spatial dimensionality.
We now know thanks to physics and cosmology just how particular and material that "deep geometry" actually is. It is not Platonically existent as Newton assumed to simplify his modelling. Some event - like inflation possibly - had to create a material flatness. And some even more remote event perhaps constrain spatial dimensionality to just three directions.
So physics knows that it has to push backwards from the highly constrained material state of the current universe to a description of the least constrained possible states from which the universe might have arisen.
And maths too has been following the same sort of path by relaxing the constraint on its Platonically existent objects (the impossibly perfect versions of possible material constructions).
As you say, for example, maths has gone from scalars, to vectors, to spinors. It has gone from confinement to a location, to confinement to a straight path, to confinement to a curved path.
This would be why there are the striking parallels between mathematical invention and scientific discovery. Exploring the Platonic realm of increasingly unconstrained form is retracing the steps by which a reality formed by constraints could have developed.
However there is then the question of whether that mathematical expedition has really focused on the meat of things. As I say, natural patterns, natural states of constraint, are the result of material dissipation. So working your way backwards from vortexes and scalefree networks rather than points or triangles might be ultimately the more fruitful path.
This is why the philosophy of maths actually matters.
If you believe maths is invented and arbitrary, you won't care much about the relationship of the formal world to the material world. Only the material world really exists for you.
If you believe maths is Platonic, again the relationship doesn't matter because the formal world exists in its own independent right.
But if you believe that form and material are in interaction to create reality, then this should be your philosophy of maths too. It would guide the way you developed math further, focus your attention on core issues like the way nature constructs its own constraints via material dissipation. And then how "language" can come in over the top of that to take control over natural processes.