Including is an act: something includes itself in what it is.
The derivation begins from the impossibility of nothing: for nothing to be nothing, it already needs something (a thing, equivalence, negation), so something must exist. What exists has dynamics that must be derived.
A thing is determined by its inequivalence to anything that is not itself. That is: to be something is to not be what you are not. Given this determination, it cannot not derive a dynamic of determination — the acts by which the thing enacts its own determinacy. Including is one of these acts: something includes itself in what it is. Its pair is Excluding: something excludes everything it is not.
Including and Excluding are co-derived from the same forcing. A thing determined by inequivalence must both gather what it is and set aside what it is not. Neither act comes first; both are forced together by the nature of determination itself.
Where Including produces the condition Inclusion (what something is), Excluding produces the condition Exclusion (what something is not).