This is a question that I've sort of prodded elsewhere in the past.

Basically, as I see it, a metaphysical theory's goal is to not just describe reality in its most general and fundamental sense, but also manage to include itself in the picture as well. In other words, if "all is x", then the metaphysical theory itself ought to also be x.

But is this possible? Or will there always be "something more" to whatever we claim about x?

For example, it would be silly to claim that reality is made up of ballpoint pens. Clearly ballpoint pens exist in some sense but they are too specific to be a metaphysical theory. Atoms are too specific as well. Electrons also seem too specific. These can plausibly be seen as "objects" in the loose sense. We can "break them down" to their lesser parts, or explain their existence by the relationships between them and other things.

The contemporary analytic metaphysics culture uses terms like "particular", "universal", "concrete", "abstract", "kind", "sortal", "object", "property", "concept", etc. Of course if we advocate something different, like perhaps a "rainforest realism" of sorts then some of these aren't going to applied, in particular the dichotomies between particular and universal, and concrete and abstract.

But regardless we can still ask what an "object" is, or what a "property" is. We can say that planets are objects, that red is a property, but we're only describing objects and properties by means of example. An example of an object is a planet, an example of a property is red.

Ways to get around this inevitably depend on these terms anyway. For example, we might argue that properties are "ways things are" - which in my opinion is pretty accurate and intuitive. Yet this still begs the question as to what the hell a "way" is, and what the hell a "thing" is. But I "know" what a "way" is, and I "know" what a "thing" is - it's just that I can only refer to them by examples. But I still insist that they are somehow "real".

So again, to go back, perhaps we argue that the world is entirely composed of x - let's say x represents energy. But what even is energy? Tough question to evaluate without adding in extraneous terms, which would defeat the hypothesis that all is energy. Clearly if energy has different features, then it's not really the what the universe is composed of in the metaphysical sense.

From what I can tell, in order to even conceptualize something requires complexity. Of course, I must define what complexity is, which I take to be equivalent to a structure of sorts (with a part-whole relationship, discernible properties, etc). To be complex means to have an identity.

Therefore it is hard to see how a "property" can possibly be a contender for the most basic and general aspect (what does aspect mean? lol) of the world. It's too specific - properties have an identity, they're properties!

And thus this is where the Aristotelian notion of substance comes into play - that which cannot be predicated upon. But, as Heidegger noted, even this is not enough, because substance necessarily exists - but we have not explained what it means to exist (Being). Substance is defined as a fusion between matter and form - yet matter and form are still names for something - matter and form. Yet what is matter and form? And the regress begins...

So the overall point being made here is that it seems as though if we can name something, that is, identify something as something, then we can always ask what else is behind the curtain, supporting this something. Thus complexity, and thus intelligibility, cannot be the fundamental and general aspect of reality. It seems, rather, that intelligibility must emerge from a processual background of the unintelligible, or that which cannot be predicated upon whatsoever, including indirect names like "the infinite" or "the apeiron" or "Nothing". For we can always ask what makes it the case that whatever it is, is what it is. The intelligible must evolve - or, rather, intelligibility must make itself intelligible. Within our cocoon of intelligibility, we exist. Yet intelligibility is only intelligible to those in which exist within the intelligible - just like how foreign languages are unintelligible to outsiders. There doesn't seem to be anything objective about intelligibility - it's merely something that happened.

If we can find the basic structures of intelligibility, then these basic structures can yet still be scrutinized. Like baking a cake - we have flour, yeast, sugar, salt, milk, butter, etc. Yet clearly these ingredients exist in their own way. So how do they? Similarly, we can see how reality is "made up" of properties, objects, relations, sets, change, time, etc. Yet clearly we can also identify these parts are things-themselves, since we have identified them. Perhaps we try to eliminate some of them. Perhaps we try to argue that time is just change, or that change is just the addition/subtraction of properties in objects. But this method merely pushes the can down the road, pushes the explanation further and further away. Things keep getting reduced to other things - when does it stop?