>>But the objects of our knowledge are manufactured by our mind. If so do these objects, exist in and of themselves or are they illusions? <<
Hello, Mitchell. I'm not sure how you define illusion, but I can give you an argument that the objects of thought exist in and of themselves - i.e., the objects exist independently of an interpreter. That conclusion is based on two assumptions: (1) The Big Bang (or some other "starting time or times" vitalized by energy) is valid; and (2) E=MCC. Then:
1) The Big Bang created a Universe of energy;
This establishes an interlocking structure of physical ideas. And what are these "ideas"? Since they are composed of energy, ideas are physical particles arranged in unique designs - designs mandated by the power relationships - energy relationships - among the particles composing the ideas.
I am not a logician, and can't phrase 1-7 above to the exacting standards I have seen in this forum. But to me the "sense" of the argument is clear: 1) we live in a physical universe; 2) the ideas that exist in this universe are also physical; 3) these ideas (like Plato's Ideals) exist independently of an observer.