Contra Metaphysical Idealism

[Chas]

If reality were reducible to thought, then we dreamed up 13.78 billion years of the universe that existed before we did.

For your contention to be true, ancient Homo sapiens would have to have dreamt up a universe that acts like the universe modern man has dreamed up.

Your concepts are self contradicting, essentially incoherent.

I see. There's still a disconnect between what I've said, what I mean, and what you think I'm saying and meaning.

When I say the universe is reducible only to concepts, I don't mean that the universe is created by the mental activity of people. I mean that the essential nature of the universe is that it is built on the interrelationship between concepts or ideas which exist independent of a human observer. So even given all of evolution, and an understanding of brain function, and the relationship between brain structure, its chemistry, and a person's subjective experience-- the fundamental "stuff" underlying all this has no tangible reality, and can only be described mathematically or metaphorically.

And that is something entirely without evidence or possible mechanism. Where do these 'concepts or ideas' reside? All you seem to be doing is restating Platonism.