Bishop Berkley said that “reality” is a set of inputs G-d feeds into our souls. In His compassion, he allows us to work together by giving us consistent worldviews with each other. Which is why when a tree falls in the forest and there is no one there to hear it, it makes no sound. But then, there is really no tree nor that part of the forest, either.
I don’t believe that.
The Tanya (the defining text of Chabad chassidus) says that the only thing that exists is G-d, then when we say “there is none but Him” we don’t just mean no other gods, but nothing at all else exists but Him. The Lurianic notion of tzitzum, Divine “withdrawal” to “make room” for the universe is deemed an illusion. Thus, the problem I’m avoiding by a judicious use of quotes, or throwing in a “so to speak”, they use to prove it can’t be real. G-d can’t really limit Himself. He gave us free will, and thus the illusion of being independent entities. And everything else we see that we think is independent is part of that illusion. It’s a different form of reality is all in our heads, in creating such a gap between the One Real “Thing” and the many things we think are there. In Chabad writings this is associated with “yeish meiAyin” (something from nothing, the Hebrew version of ex nihilo), which they would have to write with that capital “A”. From G-d’s perspective, He is the Yeish (Something), and everything else is ayin (nothingness). From without our illusion, He is the Ayin, and we are the yeish that comes from that nothingness.
Kant was less extreme. He spoke of the neumenal, that which is actually “out there”, and the phenomenal, the world as experienced. He believed there actually is a neumenal universe that lies behind what we do physics on, but we don’t really know what’s it’s like. E.g. he tried to prove that time and space are phenomena, not inherent.
Esnst Mach (after whom they named the speed of sound) and Einstein took this one step further and used it to explain why science is possible. The latter often said, “the most incomprehensible thing about the world is that it is comprehensible”. How is it that our mind’s logic matches the world’s rules? Not just one the gross scale, which is obvious what shaped that mental logic was the ability to make sense of the events around us. But even in details like coming up with tensor calculus just a few years before it became the central way of expressing General Relativity? Science has gone well beyond the intuitive or that which would give a particular kind of mind more survival value. And yet we can still reason about the universe. Their solution: We are analyzing the phenomenological universe — the kinds of things we can measure and find patterns in is itself shaped by the structure of that mind as the theory created to explain it.
Rav Dessler has his own variant of this notion. He asserts that the flow of time is a phenomenon, created when man ate from the fruit, and his whole worldview became centered on desire, pursuit, and attainment (or frustration) — a time sequence. He uses that idea to discuss time during the week of creation; according to R’ EE Dessler, the concept is entirely incomprehensible, and one could give it any duration depending on how you look at it. It was literally a week, literally billions of years (but that’s a sadly materialistic perspective, in his opinion), and also literally the subsequent 6 millenia of human history. Doesn’t make sense? Right — neumenal time doesn’t fit how we think.
He has a similar approach to nature vs miracles. A person has to be very different than the norm, but he could reach the level where moral law defines his phenomenological universe more than physical law. Such a person experiences miracles. Even if it means someone else would experience a conflicting reality!
(My own position is along Rav Dessler’s lines, as you can tell from all the links to places where I discussed various elements of it in more detail.)
I think it is worthwhile to note this piece from the Ba’al HaTanya’s Shaar Yichud chapter 7.
“ומקיימן העלום להיות עולם כמות שהוא עכשיו יש גמור דבר נפרד בפני עצמו ואינו בטל במציאות ממש”