Trouble is, I don't know even what a posited mind tree would be. I guess you mean the idea of a tree. But the idea of a tree is not a tree.
Well that depends upon the context of the question.
If we are positing a universe that is entirely made of mind, then everything is mind ........ from trees to science to ideas, everything. The world of no head.
If we are positing a universe where mind is confined to perception, and there exists a physical world outside the brain, then yeh i guess you could call a mind tree an idea. The world where we all have heads. And for sure, an idea is not the thing in itself.
The question of what we mean as to a tree existing
(falling or otherwise) needs clarity with regard to mind/outside mind distinction. An idea tree exists and an outside brain tree exists concievably differently in a world where we have heads.
For the world of no head....... A mind tree can possibly exist but is presumably indistinquishable in the sense of existence to anything else since in such a posited world all is mind. (Though the idea of an unconscious mind tree as compared to a conscious mind tree could possibly be different with respect to the meaning of the word 'existence' depending upon the world mind scheme we are considering. eg b) and c) above.)
But of course if you cannot concieve philosophically of a world entirely made of mind then thats fine. Whats wrong with that?
I would point out the following however. Suppose
- We do not see the tree we see the light from the tree. No we do not see the light from the tree we see the neural activity that results from the light from the tree. No we do not see the neural activity that results from the light from the tree we see something else that is the effect of neural activity .... namely consciousness. Thus we do not see the tree or the light from the tree. We know this from dreams where the neural activity exists but the light and the trees do not.
BUT this implies that all that you see comes from INSIDE the brain. Thus an entire landscape is inside the brain. Presumably therefore there is by logical extension of this model of universe and perception ....... a massive skull encasing our perceptions! Not a nice thought. But of course the concept of 'outside' is itself inspired by the act of consciously seeing something other than light and trees. namely inner
consciousness.Thus to project the existence of a skull encasing our three dimensional landscapes of vision. is itself a biased projection of meaning derived entirely from within the mind. ie perception itself. Perception of landscape provides the logical metaphor of the encasing skull by giving us the concepts of spatial outside and inside through vision.......
But wait a minute.
The very same neural evoked landscape must by the very same arguement be equally biased in projecting the whole original train of logic from tree to light to neural activity to consciousness inside the head in the first place! Thus it is a circular arguement. "We know we have a head because our entirely internally concieved perceptions tell us we see an outside world" This is a very dodgy philosophical arguement.
The dodgyness of the arguement does not disprove we have heads ...... but it is dodgy, and doesnt prove it either.