Total skepticism. Well, I said it because it seems intuitively true, but perhaps there is some way to do it. The problem with a total skeptic making a defense of his or her position is the defense will contain arguments. These arguments will be based on observation, or deduction, or assertions or something. To defend you must assert something, even if it is only in the negative. "We cannot know what we perceive is real" Oh, really. How do you know that? How do you know I can't? For example.