Kant’s metaphysics can be summarized as follows:

Part I: Epistemology

The bottom of the self is agency. So when we say that a cognition (perception) reaches the subject, or hits home, or becomes illumined, or that it makes the journey from object to subject—we mean that the object has made contact with, or ontologically overlapped, our agency. The metaphors of touching or tasting are what we want here. The object that is illumined for the subject reaches its volitional core. The most core aspect of the subject for Kant is its act—doing that proceeds from the nothing of fiat.

Agency makes by rules (see below for more), which we name and use in propositions. The act of perception is also one of cognition, aka judgment, aka producing a “fact” by carrying out a weird ritual of production. Reason’s asymptotic pleasure of creating-beholding does not hold only for content-like knowledge, though that is the most intelligible and model case. In the simplest case I posit an image from a concept (rule) and then immediately recognize this image as being F. For example, I pick red and make a red splotch. That is a simple and comprehensible act of production.

Kant’s genius is this: the act of proposition-saying is also an act of production. And the product here is object-like, that is, it is an agent-external terminus for the agent’s intentionality, a pole that is other than the act of positing that the subject perform at home. But the nature of this terminus is act, specifically, a rule of act. Acts of positing, as well as posited content, originate with the subject. The physical object is only partly empirical content; the rest of it, indeed its very guts, are types of activity. We posit activity just as much as we posit content; types of activity types are just as objective as types of content.

This is how Kant overcomes Hume—by enriching the notion of positing and object-making. Hume recognizes only one a priori principle of positing, which is the PNC. To this he adds the three natural (bogus) relations of resemblance, contiguity, and cause and effect. For Kant, however, object-positing is enriched with forms besides the PNC that are yet necessary.

Experience, or epistemic subjectivity, has three ingredients—agent, action, and patient. The agent is nothing but potential action; it is not identical to this or that particular action because when action ceases the agent still remains. The action of propositional intentionality, or judgment, posits the object in a medium that sustains it—i.e., in the imagination and the forms of intuition.

Part II: Ontology

And this is Kant’s ontology. There is noumenal agent, act of imagination, and the forms of intuition that permeate imagination, which is just subject-affected intuition. Agent, action, and intuition are the fundamental elements in Kant’s ontology of the epistemic subject.

Kant’s ontology is thus the first truly modern ontology—the first one that follows the Cartesian “Order of Discovery”—because it derives from considerations of epistemology.

A note about rules

We want objective reality to be substance rather than rules, but it cannot be substance inside the Order of Discovery empirical reality is carried by inner sense, all of whose content (stuff) passes away. In a processual ontology, only rules can be truly substantial.

The problem is that we are torn between two competing schemata for the real—the quale of muscular counterforce (mass, impenetrability) and the real basis for physical inertia, which is perpetual dynamic or periodic reconstitution.

Ironically, it is the rule that is the best explains our prejudices for substance metaphysics—that is, for both (1) our guess that the ontological bottom of the noumenal is a substance-like principle of perdurance, and (2) our insistence that the bottommost real in the physical is, whatever its content, temporally self-identical. We want there to be a stuff that is enjoying this unstoppable arriving at shore of the next moment, something extended and repulsive, because only a stuff (it seems) could realize our first empirical encounter with reality, i.e., the muscular-effortful counterforce of mass. Temporally self-identical mass is, we hope, the hero who traverses temporal passings away, who crosses the passing of inner sense, a point that journeys across time in the same way that an identical point traverses space.

But such is not to be found in experience, for every real is also an in-time, every truly present sense-content, every high-vivacity and power—power that overwhelms willed sensation, or imagining—is also a passing content. In other words, every real is presented by a power whose power forces the passing. Each real overwhelms. The arising-real pushes away the just-arisen, which becomes the passing-real under the power of the vivacity of the present presentation. Presentation is power.

Mass, our hoped-for hero, cannot be the bottom of the real, because counterforce is an empirical content that passes and is a predicate. Thus substance cannot be strictly identical to present vivacity because its power manifests as the arising that pushes passing.

We need a substance that has nothing to do with the content of impression. Real substance must be empirically empty. But this leads to two problems:

1. How can we know a non-presence (the argument from empiricism)?
2. How can we know that a non-presence is identical across time.

The answer, of course, is rules. The micro-structure of substance is not the perdurance of mass, but the perdurance of rules of reconstitution—Kant’s the synthesis of reproduction.