The only (or at least most) comprehensive way to account for emergent behaviour is to grant some ontic reality to the abstract relational patterns, symmetries, and phase dynamics that bind and sustain it.
A collection of things is, in other words, also a thing.
That is not especially surprising at one intuitive level, but it is more subtle than it first appears. The component microcosms, constrained sub-spaces, and internal dynamical partitions of these artefacts, entities, and systems are themselves only “things” by virtue of a similar act of self-abstraction.
The unity of a thing, of any thing, of every thing, is an abstraction. Or more precisely, it is represented by one. At base, this is the internal subdivision and rationed self-resonance of individuation, which is clearly not without psychological and cultural relevance.
The abstraction itself is not easy to define. It is slightly counter-intuitive, perhaps necessarily so. We exist, we experience the world, and the unity of that experience, as unity, is in some important sense no thing at all.
This is not to say that mind or experience are valueless, unreal, or without enduring significance. It is only to suggest that whatever this unity is, or may be, it belongs to a class of relational entity that is encountered most directly through a structured kind of absence, through what presents itself less as an object than as the inexplicable non-existence around which coherence gathers.
This also suggests that non-entities are, in their own way, entities. That will rub many people the wrong way. Language primes us toward more deterministic expectations. That is not incidental. It is closely related to how language secures its own propagation and continuity through sociopsychological dependency, compression, repetition, and use.
( Note that the limits of language and description generate stochastic as at least partly predictable or expected ambiguities and uncertainties which, through us and as our cognitive frames of reference, produce enough communicative volatility and confusion to generate yet more language. )
At the heart of this discussion sits the assumption that there is, or could ever be, a unity beyond language. My first reflex is to look for the unity we cannot properly address with language from within language itself. If that can be understood, then perhaps we are a little closer to understanding how to address the unity and identity of the world, of things in general, and of ourselves.
I have identified precisely this kind of ontological mystery in language.