Existential Import

[JuliaL]

Idealism ftw.  All those things you are talking about are demonstrably real only as ideas.  Put your ball under the microscope, and poof! it disappears.  It was only ever really "a thing" in your mind to begin with.  That this non-thing is highly coherent and behaves consistently through time and space means that all those QM particles are just down with the program of supporting the ideas of things.

But the the QM particles you offer in trade are no more supported than the ball.
I think I think therefore I think I think and no more....I think.

Morality and mythology clearly can exist only as ideas.  But there's something important to consider: your view of the people around you is ALSO a mythology.  Mom is "actually" a collection of wave functions vibrating in space.  There's no objective "beauty" for her to have, or kindness, or love, or her sense of what is right: NONE of the qualities by which you define a person actually exist.  Even the curves of her face are ideas: the brain organizing the general distribution of light into descriptive shapes, when in fact there is nothing there but a gazillion individual photons travelling in a straight line from an emitter to your eye.  You experience not the existent entity, but a mythological interface between your ego and the idea of "Mom-ness," which you believe you perceive but in fact have created as a kind of "best fit" for the collection of random perceptual memories you've stored and tried to relate to each other in as simple a way as possible.

I'll go along with you if we can tentatively agree that we're all self aware neural nets in a vat (of cerebrospinal fluid).
Given that, then all the percepts and whatever is built from them are vibes in the mind.  Even the vibes in the mind are vibes in the mind because they exist as patterns of neural discharge, synapse potentiation and dendrite geography evolved by sense and internal modification of prior configurations.  We build patterns of patterns based on prior patterns and call them beauty, love, Mom and the idea of threeness.  Other than patterns in the brain, I don't see where the logical absolutes or any other ideas could reside.  And wouldn't trust the validity of the observation if their locations were pointed out to me.

So in my opinion, you don't have to justify anything.  Your so-called perceptive existence is just that part of your conceptual existence which is dependent on input coming (unless solipsism) from outside the self.  But by the time you get around to perceiving it, it's not qualitatively different than a vivid dream, which of course comes fom the self anyway.

Thanks for the 'unless solipsism'  everybody seems to ignore that this is all contingent then gets mad and frustrated when such is pointed out. 
But it's been a good dream and so much more consistent than REM sleep dreaming.  I'm inclined to trust it and predict its unfolding confident my actions to optimize future states will be fruitful.  And because AFAIK I don't have any other choice.