Justin asked:

Why do skeptics use reason to deny things when any arguments they can propose are made up of
notions they should not believe in as skeptics?

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Because they are trying to cover all possible cases, basically. If you have an argument that is only
true someof the time, then how do you know when it's true? But if you know it's true allthe time,
without exception, then you're set, right? So, in order to determine that, you try to take the absolute
worst cases, and if you're still ok, then everything else works. So that's what a skeptic does; or
conversely, a skeptic shows that in some very bizarre situations, some argument just doesn't work.
Well, then it doesn't work, period, because if it doesn't in somesituations, then where or how do you
find the line for when it does, always,work? But if you do manage find that line (assuming you can at
all), then you can just recast your argument to be within those new boundaries.

So if someone says that you can't be sure the world exists because a demon might be causing
everyone to hallucinate it all (Descartes' argument), then, sure, nobody reallybelieves that... but it
leaves them in a dilemma. If you can't refutethat claim, then what can you know is certain? Where is
the line, and how can you prove that yourline is the correct one? Descartes' boundary was between
our thoughts and reality... whether or not a tree exists, we know that we are experiencingseeing a
tree, even if some demon is causing us to hallucinate it. So we have certainknowledge of our
experiences (or, actually, when you really get down to it, thatwe are experiencing something which
we think we remember is a tree). So what the skeptic has done, with an extreme example, is to show
that if we're going to talk about certainty, if we wantcertainty, then we have to be very careful indeed.

Steven Ravett Brown