Is our known reality just an illusion?
Lets take this apart as any good Analytical Philosopher would do.
Reality and Illusions are aspect and anti-aspect of Being (IS) along with identity, presence, truth and their duals.
The idea that we know reality, identity, presence and truth is somewhat of an oddity. This is because Being has usurped the place of Knowledge in the Indo-european worldview. Being is suppose to be perduring, but it is actually knowledge that is perduring. It is fairly clear that Heraclitus who embraced change was more right than Parmenides who rejected change.
Now the problem is that there are meta-levels of Being and that the aspects are different at each meta-level, and so to know the aspects we must know what the aspects are at each of the meta-levels of Being, i.e. Pure, Process, Hyper, Wild, and Ultra.
“Our” of course refers to the Mitsein, i.e. the inauthentic masses lost in the mundane who have not yet realized that they are in fact dasein, i.e. something deeper than subjectivity/objectivity dualism.
Given this analysis we can say that if we do not know what reality is at all the meta-levels of Being, i.e. Pure Reality, Process Reality, Hyper Reality, Wild Reality, and Ultra Reality and its opposite at each level, i.e. illusion, [and include in that all the other aspects and their opposites (truth, identity, presence)] then we can never tell whether the reality blends with the illusion or not. We have to make a non-nihilistic distinction at every level, and that becomes harder at every level because it is harder to think at each level. Reality and Illusion become more intertwined at each level. So basically reality IS illusion and illusion IS reality, because Being itself is really absurd in itself at the level of Ultra Being where it becomes a singularity.