Dear Philip,
This is very well written essay, and an enjoyable read.
I read quite a long time ago, and I think I am now on my third read. I guess that I really have a different perspective.
You have a logically-ordered ontology of mathematics which you present metaphorically. And central to this is the idea that there is some sort of universality around which the mathematics converges rather like a critical point.
While on the surface, there is something attractive about this idea. However, there are some seemingly paradoxical aspects that arise the more that I think about it. First, you don't seem to differentiate between types or classes of mathematical theories or descriptions. And because of this, it then seems odd to develop such an ontology, since in doing so, the act of creating an ontology (or ordering) would be inherently mathematical. So this then begs the question "What type of mathematics allows you to develop an ontology of mathematics and where does this fit into the resulting ontology?" There is something circular about this that is unsettling.
On a different point entirely, I think that it is very telling that you (even in your title) are relying on a metaphor. This creation of models via metaphor is a critical aspect of science. David Hestenes' essay takes this stance, which leads to mathematics as being an analogy-based tool for thinking.
I agree strongly with his approach. Symmetries are particular cases of analogies, and in my essay, I show explicitly how the symmetries of associativity and commutativity (along with closure and ordering) result necessarily in additivity (up to invertible transform). Thus, any description of a system that has those symmetries must result in an additive theory. This suggests that the universality lies in fundamental symmetries (such as commutativity, associativity, distributivity---which are not the same as physics-based (higher-order) symmetries such as isotropy of space, gauge invariances, etc).
Now, you actually make some comments about symmetry and note that some people see symmetries as being emergent. I believe that some are. They are emergent from the chosen description. But they still could be the source of the laws. Another objection that you point out is the fact that some theories known to be dual to one another are based on different symmetry groups. However, this is not an argument against the universality of symmetry. Instead it highlights consistency in/and among the chosen description/s.
In the post above from Laurence Hitterdale, he points to logic as being the universal principle. In your response, you seem to agree with this. However, it is not specified which logic you two are discussing. But either way, logic is a particular example of symmetry/order, which again places those concepts at center stage.
To me it seems that your exercise in constructing a metaphor for an ontology of mathematics highlights the critical nature of metaphor and analogy in science, which supports symmetries as being central as Hestenes and I discussed in our essays.
I think that there are some deep ideas/insights here that can be extracted. I would like to know your thoughts if you have a chance.
Again, thank you for a very enjoyable and thought-provoking essay.
Kevin Knuth