※ 引述《china2025 (2025全面小康)》之铭言：
: 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.
: 以上是节录一段网站桶中脑的文章
: 我觉得premise1 是个有问题的句子
: premise1: If I know that P, then I know that I am not a brain in a vat
: 请问大家 "如果我知道P 那么我不是桶中脑" 这句为什么会成立?
: 我看了版上关于桶中脑的讨论 都没有人质疑Putnam 我觉得很奇怪
确实怪怪的 not sure => can not rule out the possibility that P is false
逆反命题为
can rule out the possibility => sure
就算能确认P是对的，也只能sure BIV or not.
有可能他是知道外界知识、但现在在桶中脑状态的人。
但我想他想表达的是
前提：桶中脑经历的一切不可称为真实，
1.如果我确定知道了真实，我就确定不是桶中脑
2.我不确定我是否为桶中脑
3.因此，我不确定我知道了真实。
而且要加个条件，知道真实者，不可成为桶中脑。
: ※ 引述《aletheia (HERESY)》之铭言：
: : 桶中大脑（BIV）。
: : 常被用来当作反对外在世界存在的例子。
: : 就形上学来说，BIV的确反对形上学的实在论(MR)
: : 但以知识论来说，BIV不反对知识论上的实在论(ER)
: : 何解？