Below is a playful exploration, a thinking out loud, a prelude of a pragmatist process metaphysic. Be warned that it's not for the faint of heart, and is a throwback to styles of philosophizing barely remembered in contemporary academic philosophy. If it's too much of a slog, go to the comment and questions at the end.
Experience is of "things-in themselves."
If we begin with the position that "things-in-themselves" exist, then we are easily lead to believe that we must take up a relation to it in order to know it. But then, we are forever bound in the question of what is the "thing-in-itself" without our knowing relation. This is a false dilemma that is sometimes called the problem of "access," the post-Kantian problem, although its roots go deeper and earlier.
The significance of the false dilemma hinges upon whether relations are real, i.e., whether being related is constitutive of what is related. If yes, then relation constitutes the thing such that altering its relations alter the thing. If no, then "things-in-themselves" cannot be related, and therefore cannot be known. This manifests a number of contradictions that thinkers such as Leibniz and Spinoza sought to solve, and the oddity of their systems should point to the problems of beginning with such a starting point. Kant did not solve this problem, but re-inscribed it. Now we know the "phenomena," but not the "noumena," and we have gained less than either we wanted or thought.
Suppose we accept the relativity of "things-in-themselves," and solve the problem of predication, i.e., the question of how much of the nature of a thing is due to itself or to relation, by dodging the question. We propose asymmetric relations, where the genesis of difference is asymmetry in time. That is, a thing is self-similar or in-itself, but its relation to itself as self-similarity is temporally asymmetric. It is itself in one moment, but in the next it is merely self-similar to what it was before. It has changed. Then, we may speak of the "in-itself" and the "for-itself," i.e., what a things is or its identity, and what a thing may become. The for-itself is dependent upon the in-itself, but neither necessity nor accident are the names of this relation. The relation is constitutive, but such necessity is trivial, whereas the contingency is non-trivial. Thus, what was an "accident" is raised to the "contingent" that is no longer arbitrary because a historic contingency has real effects.
Suppose, further, that in accepting relativity and asymmetry, we recognize a problem. Does the in-itself or for-itself change? Have we just re-inscribed the subject-predicate duality? If neither the in-itself or for-itself change, then the whole is a static development scripted from the start. If only the for-itself changes, then how do varied different self-relations amount to plurality? That is, if the in-itself is wholly atemporal and is not changed by the flux of the for-itself, then the development of the whole is characterized by a difference that does not make a difference. That is, if the in-itself or essential identity does not change, while the for-itself or its development does change, then we are split apart. A horse without a wagon. The distinction becomes not pointless, but less than we hoped. We could then only explain plurality through positing a multiplicity of the in-itself. Even if we allowed the multiple for-itselves to interact, we still face the problem of the necessity of positing the universe of the in-itself, a starting point. They may develop into a plurality, but they each began as posited seeds. We must address the in-itself, its eternity, its essential identity, the stubborn wagon to which the horse is attached.
Suppose that the in-itself is not posited at the beginning, but comes to be through the interaction of the for-itself. Then, we need only posit the existence of the for-itself, the drives of the cosmos or all those little points of will. When they come together in a nexus of activity, when they concresce, they manifest an in-itself or determinate identity. The various forces cancel each other out not in annihilation, but creation, energy to matter. Hence, plurality begets identity and not the other way around. The plurality of force generates the singularity of identity, as if the predicates generated their subject after having overthrown their Aristotelian master. Hence the many become one, plus one, but we may begin with an indefinite many rather than wrestle with either a determinate many or one.
"Things-in-themselves" were split into the in-itself and the for-itself, the identity and generative principles. While the split was helpful, it was incomplete, because if the thing-in-itself is responsible for both its identity and generation, then change always appears illusory. If we keep the split but dislocate the in-itself into a nexus of other for-itselves, the identity of a thing into the generative principles of other things, then we solve two problems. First, the many came first, and constitute the one, but only in the one is the many determinate. That is, force came first to constitute determinate existence. Once constituted, that in-itself gains this for-itself, and the thing-in-itself continues as such as long as its constituents are stable. Second, whiel the many came first, we need not posit a fixed beginning. There was a plurality of force, a basis of for-itself-ness that need not be determinate. Positing such determinacy would invoke the great problem of Schelling and the seeds of the cosmos; how to think generativity and freedom without limiting the logos at the beginning and therefore limiting freedom.
Experience, then, is of things-in-themselves because it includes the in-itself or identity as well as the for-itself or generativity. Human experience is part of the possibilities of generativity.
In hindsight, this reads like a hommage to German idealism. Especially its obscurity--ever read Schelling or Hegel with no knowledge of commentaries?--although I actually have an articulated point. I will likely present these insights in normal English, since it announces a radical insight in my thought. There is nothing novel here except my own understanding of what questions process metaphysics answers and why it must do so.
What is the relation of things-in-themselves to others?
What is the relation of the in-itself (identity) and for-itself (change)?
Did the cosmos begin as one or many? If one, how comes many? If many, whence comes oneness?
That is, how did any determinate identity generate a true multiplicity?
Or, how did any multiplicity generate a determinate identity?