I am more familiar with Kant than with Plato. Would you agree that for Kant the the physical exists but is unknowable in itself , the mental exists in itself but is empty without sensations from the world ('concepts without percepts are empty; percepts without concepts are blind‘). So Kant’s metaphysics shows us that the physical is an ideal , not an actuality. It is an ideal in a different sense than the mathematical concept of zero, yet still an ideal. Therefore his metaphysics is showing us that ‘what is’ ( both as fantasized concept and as physical ) is the product of an indissociable interaction between external reality in itself and subjective mental process. — Joshs
I'm not an expert on Kant or Plato. But I would hazard to say that Kant's
Noumena is equivalent to Plato's
Ideal. However, the Ontology of those terms is debatable. By definition, the "Ideal" is not "Real" -- they are contrasting Either/Or concepts. But what does that mean in practice? My full-spectrum worldview is
Both/And.
As you noted, our mental Concepts are mostly based on our physical Percepts. Our mental worldview is constructed from basic elements of perception and sensation. But we also create abstractions that bear little resemblance to concrete Reality. Yet, I can't imagine a mind that is completely disconnected from the physical world. And yet, it's true that our self-created conceptual worldview (e.g. Surreal Art) can mix & match the elements of mundane Reality into bizarre unreal forms. For example,
Psychonauts, who experiment with drugs (opening the
Doors of Perception), claim to experience a "higher" mental or spiritual realm divorced from reality, where the body & ego don't exist. Personally, I have had no such subjective experience. So, I have to take their word for it . Such
noumenal "sensations" are completely foreign to my own drug-free mundane reality.
That said though, as a way to scientifically conceptualize the distinction between our Percepts and Concepts, I like the metaphor of an "Interface Reality" used by Don Hoffman in his book,
The Case Against Reality. He doesn't deny that there is something "out there" for our senses to perceive. But like Kant, he concludes that our personal conception of that underlying Reality is a simplified symbolic abstraction of "what-is".
Interface : Window to Reality :
Now, cognitive scientist Hoffman has produced an updated version of Kant’s controversial Occult Ontology. He uses the modern metaphor of computers that we “interface” (interact) with, as-if the symbolic Icons on the display screen are the actual things we want to act upon.
http://bothandblog6.enformationism.info/page21.html
Both/And Principle :
* My coinage for the holistic principle of Complementarity, as illustrated in the Yin/Yang symbol. Opposing or contrasting concepts are always part of a greater whole. Conflicts between parts can be reconciled or harmonized by putting them into the context of a whole system.
* Conceptually, the BothAnd principle is similar to Einstein's theory of Relativity, in that what you see ─ what’s true for you ─ depends on your perspective, and your frame of reference; for example, subjective or objective, religious or scientific, reductive or holistic, pragmatic or romantic, conservative or liberal, earthbound or cosmic. Ultimate or absolute reality (ideality) doesn't change, but your conception of reality does. Opposing views are not right or wrong, but more or less accurate for a particular purpose.
http://blog-glossary.enformationism.info/page10.html
Ideality :
In Plato’s theory of Forms, he argues that non-physical forms (or ideas) represent the most accurate or perfect reality. Those Forms are not physical things, but merely definitions or recipes of possible things. What we call Reality consists of a few actualized potentials drawn from a realm of infinite possibilities.
1. Materialists deny the existence of such immaterial ideals, but recent developments in Quantum theory have forced them to accept the concept of “virtual” particles in a mathematical “field”, that are not real, but only potential, until their unreal state is collapsed into reality by a measurement or observation. To measure is to extract meaning into a mind. [Measure, from L. Mensura, to know; from mens-, mind]
2. Some modern idealists find that scenario to be intriguingly similar to Plato’s notion that ideal Forms can be realized, i.e. meaning extracted, by knowing minds. For the purposes of this blog, “Ideality” refers to an infinite pool of potential (equivalent to a quantum field), of which physical Reality is a small part.
http://blog-glossary.enformationism.info/page11.html