※ 引述《china2025 (2025全面小康)》之銘言：
: http://www.iep.utm.edu/brainvat/#H2
: The Brain in a Vat Argument
: The Brain in a Vat thought-experiment is most commonly used to illustrate
: global or Cartesian skepticism. You are told to imagine the possibility
: that at this very moment you are actually a brain hooked up to a sophisticated
: computer program that can perfectly simulate experiences of the outside
: world. Here is the skeptical argument. If you cannot now be sure that you
: are not a brain in a vat, then you cannot rule out the possibility that
: all of your beliefs about the external world are false. Or, to put it in
: terms of knowledge claims, we can construct the following skeptical argument.
: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
: Let “P” stand for any belief or claim about the external world, say,
: that snow is white.
: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
: 1. If I know that P, then I know that I am not a brain in a vat
: 2. I do not know that I am not a brain in a vat
: 3. Thus, I do not know that P.
: 以上是節錄一段網站桶中腦的文章
: 我覺得premise1 是個有問題的句子
: premise1: If I know that P, then I know that I am not a brain in a vat
: 請問大家 "如果我知道P 那麼我不是桶中腦" 這句為甚麼會成立?
: 我看了版上關於桶中腦的討論 都沒有人質疑Putnam 我覺得很奇怪
確實怪怪的 not sure => can not rule out the possibility that P is false
逆反命題為
can rule out the possibility => sure
就算能確認P是對的，也只能sure BIV or not.
有可能他是知道外界知識、但現在在桶中腦狀態的人。
但我想他想表達的是
前提：桶中腦經歷的一切不可稱為真實，
1.如果我確定知道了真實，我就確定不是桶中腦
2.我不確定我是否為桶中腦
3.因此，我不確定我知道了真實。
而且要加個條件，知道真實者，不可成為桶中腦。
: ※ 引述《aletheia (HERESY)》之銘言：
: : 桶中大腦（BIV）。
: : 常被用來當作反對外在世界存在的例子。
: : 就形上學來說，BIV的確反對形上學的實在論(MR)
: : 但以知識論來說，BIV不反對知識論上的實在論(ER)
: : 何解？