Interesting discussion, but it is further evidence of many shortcomings which have impoverished Kant scholarship for too long. What is being assumed here is that Kant is really just a First Critique Kantian, but he wasn’t. Kant’s transcendental philosophy is much bolder than conventional wisdom has it. I take Kant at his word when he claims to be working out a CRITICAL philosophy, not just writing a First Critique, Categorical Imperative, constructing an epistemology, or whatever. You cannot read the First alone, but especially not without the Third and his popular essays which are too often ignored! The power of determinate judgments (Pure Reason) presupposes reflective judgment. Reason and Understanding are both forms of determinative judgments where particulars are subsumed under universals. Therefore, they both serve a legislative function. But in the case of reflective judgments, universals are the domain of all possibilities. Subsumption really entails the exhausting of all possibilities into the actuality derived in the domain of action.
It is absurd to assume that of the human cognitive powers (understanding, reason, judgment, imagination) only some have an independent legislative function because they ALL do. The focus of the First Critique is the subsumption of particulars under universals—when a predicate determines its subject, which is not that interesting from the standpoint of logic. But the Critique of Judgment (1790) investigates when a subject determines the predicate or when a particular goes in search of a universals, which is a hallmark of aesthetic judgments of taste! There Kant explains imagination as this “free-play” of reason and understanding through reflective judgment. It is our mediating power of imagining possibilities that might not even exist. It is having the possibility of reflecting upon possibilities which is required as a prerequisite for us to have ANY objects of cognition or engage in acts of the will. The first critique deals with the relationship between judgment and understanding; 2nd critique pertains to the power of reason in relation to judgment; 3rd critique analyzes the relations between reason and understanding in comparison with judgment. Reason is the experience of enlivening the body; Understanding pertains to the cognizing of experience or an empirical object; Judgment is the power of subsumption. Judgment brings the relation of the three together in such a way as to facilitate action, which have ends always in mind. Reflection is putting the possible before the actual. Transcendental philosophy takes this “reflective turn” and asks what within the domain of the possible is actually necessary. It can be done in two ways: 1) negative elimination of the possible and acting on this; 2) looking for the forms or acts of every actual moment will lead us to the domain of possibilities (e.g. space and time).
This doesn’t give us knowledge regarding the intrinsic constitution of these forms but are the conditional circumstances of our experience. Transcendental philosophy seeks to uncover the invariant aspects to the process of understanding, which presents objects of cognition according to the sensible manifold. The understanding is a process of synthesizing the sensible manifold according to the “lawful character” of natural processes. An element of judgments regarding our subjective constitution has a domain of universality. Subjective universal is the involuntary feeling completing an act before it even occurs because of given anticipatory structures within the domain of reflective judgments. Within the entire domain of action there is always some element of freedom because of putting possibilities in front of actualities for consideration. This is the function of reflection within the domain of the will, reason, and understanding.
Kant’s view of imagination develops and continuously changes such that it would be wrong to say he has a fully worked-out, consistent theory from his pre-critical writings to the Third Critique. One can be suspect of Kant’s theory because of this weakness where the cognitive power of judgment needs to be worked out in relation to the imagination. So the critical philosophy’s presentation of the imagination as an interaction with the possible as being unstable, weak, inconsistent, and misguided in its incompleteness; it appears to be arbitrary at times and challenges the legacy of Kant’s iron-clad architectonic. The 3rd Critique gives us the power of imagination as it works with the possible in terms of how judgment uses imagination in order to employ the possible. The imagination works from the whole to parts, while the understanding and reason whether of sensible or intelligible schemata works from the discrete parts to a scrambling of the whole. The crux of imagination is our ability or power to appropriate the “possible” which adds to and helps inform what is “actual” in experience.
For Kant, the difference between pre-critical and critical writings is the difference between putting actuality before possibility and vice versa. Kant makes a wild claim that no one can think about anything which is possible through the actual. In fact, human cognition comes by way of arriving at the actual by the domain of what is possible. Reason is that energy (possibilities) by which we are moved to act everyday according to Kant. I am alive by having concrete possibilities before me and acting on them by making them actualized concretely. This is a reversal of ancient and medieval traditions. Necessity is held as merely a subset of the possible which is the basis of the Kantian revolution of metaphysics and logic in the Western tradition of philosophy. We work from what could be possible to what happened by necessity, so it is the subject that is determining the predicate. That is what I take Kant’s transcendental philosophy to represent in its entirety.
Kant’s immediate contemporaries knew this and respected it! So what prevents us today from showing the same respect to one of the greatest philosophers of all times? I recommend Ernst Cassirer’s superb intellectual biography entitled, Kant’s Life and Work for this more expansive, organic reading.