My initial reply was:
Two things that come to mind about atoms.
1. Parts partake of wholes and therefore saying a cat's atoms are most fundamental in the cat's being is to presuppose there is a formally integrated, formally intelligible "cat" in the first place. If atoms are the basis of all reality, there can't be formally discrete entities to which they belong since 'being a cat-complex' is not a property of atoms. Being an atomic complex is, however, a formal property of cats.
2. Atoms are what they are and not something else because they themselves existentiate concrete forms. I suspect there's no such thing as "fundamental particles" because even the most empirically austere particles are, on hylemorphism, but concrete acts of depotentiated matter. As such, atoms' atomicity itself already evinces hylemorphic constraints.
That reader replied by saying,
Thanks. I like your answer.
I was just playing devil's advocate, by the way. I myself am a committed hylemorphist. Your defense of hylemorphism is very good. The question is this, however: Can hylemorphism be demonstrated with certitude? I say it can be. Your argument does go a ways toward proving it, but when you say things like "I suspect. . ." I wonder if you yourself are entirely convinced. Furthermore, do you think that there is an argument that would be able to persuade the resistant, or those like David who are trying to understand the concept? It seems to me that most scientists and philosophers today, even those few that are sympathetic to classical philosophy, are unable to grasp the concept of natural substance being ontologically prior to all quantity. Therefore, they invariably identify substance per se with secondary matter, which is a quantity per se. So what is needed, IMO, is a convincing demonstration that proves that substance is prior to quantity.
But like I said, I don't think you're too far of [sic] from proving it already.
To which I replied:
Well, it's nice to know I haven't driven you AWAY from hylemorphism! ;p I used the word "suspect" in reference to the existence of what physicists like to call "fundamental particles," and I think given the methodological limits of exact physical science, there is no more fitting word than "suspect" (or conjecture, etc.), since science inherently lacks a way to PROVE its discoveries are ultimate (i.e. not falsifiable) and actual (i.e. not merely operational). If my suspicion about fundamental particles appears to be a lack of confidence in hylemorphism, that's just a foible I'll have to live with. ;p The reason I think hylemorphism is intellectually superior to any putative or prospective scientific claim, and therefore immune to crude 'falsification' by some new 'discovery', is twofold. First, supposing there comes a day when (in more or less Peircean terms) there is, in principle, no farther scientists can dig into nature––for example, because the apparatus required to explore some -nth level of physical order is so large and complicated that it would exhaust all conceivable human resources (thus leaving no observers for the post-experiment world), or the size of which would be mathematically corrupted by spacetime dilation and/or cataclysm––if at that point, scientists just agree they've found THE fundamental particles in nature (since going 'deeper' wouldn't leave behind anything coherently 'natural'), then it would still be subject to hylemorphic analysis. It reminds me of Walker Percy's idea of the indefatigable Delta Factor (viz. Peirce's triadicity): despite all efforts to 'reduce' language to energy exchanges or pure abstract necessity, the articulation and reception of that reduction would itself be subject the irreducibly human and semiotic constraints of the Delta Factor. So, again, if science hasn't 'debunked' hylemorphism by now, I see no principled reason why it could ever do so. This may not count as 'proof' for hylemorphism, but a worldview without a significant defeater is by definition significantly undefeated. Undefeasibility is probably too strong a requirement for ANY rational claim.
The second reason hylemorphism is superior to what I call perinoetic reductionism (i.e. theoretic empiricism), is that hylemorphism already gets to the heart of reality and orders epistemology in turn, whereas the former (Kantian-Carnapian) metaphysics orders reality based on our epistemological functions. Hylemorphism, in other words, is already saying what we need to make sense of reality––albeit with a number of outstanding internecine theoretical dispute on fine points––while model-based empiricism is constantly second-guessing itself about what––or whether!––reality is. Interestingly, the presence of ongoing dispute in the hylemorphic "big tent" displays its vitality, contrary to much popular bias, as an active "research program." I think the last real metaphysical opponent to hylemorphism was Hegel, since he challenged the fundamental subject-accident schema in his own way, but by now I think it's obvious his system is… well… I don't see Zizek mounting a serious defeat of hylemorphism anytime soon.