Distinguishing between virtual reality and reality: It's hard
  because there's no way to be truly objective from a non-human
  perspective.

  Through education it's quite possible for there to be not a
  single human on the planet nor any bit of written history to
  indicate a difference between a virtual reality and reality.

  It's nice to believe that there's a special class of people with
  special methods that can break free of delusion entirely and see
  "only the truth" but that's absurd; we're still all human and
  the best of methodologies will suffer from bias we can't even
  see, because there's no non-human objectivity possible just yet.

  Until then, we just have to hope for no mass delusions going on
  at present that none of us can see or measure. Then again, we'll
  never know.

  So, we have to work with the limitations that we have for now
  and hope we're doing it right.