三个主要分支：
Metaphysics 形而上学 宇宙、世界和存在的本质
Epistemology 认识论 如何认识知识
Value Theory 价值论 ---
哲学家的工具箱 --- 逻辑 Logic
逻辑用于推理，为了行成没有 谬误 的论证。
柏拉图 --- 三重灵魂：
柏拉图相信最完美的人类总是受理性灵魂的支配。
deduction 演绎 / induction 归纳 / abduction 溯因(通过排除可能的解释进行推理)
柏拉图 《理想国》 Myth of the cave --- reality shock
物质世界的平凡现实，只是最高现实的近似影子。
勒内·笛卡尔 René Descartes
Early 17th century
Cartesian Skepticism
If he examined each possible belief carefully, and onlu acceppt those about which where coule bu no doube, then he'd know he was only believing true things.
把自己相信的事实倒空，逐一检查并相信其中真实的部分。
从 Empirical belief (Deliefs that we form through the use of our senses) 开始，然而感官不一定是正确的。
Local Doubts
Doubts about a particular sense experience, or some other occurence at a proticular point in time.
在离开 local 之后，就能察觉 local doubts 的错误性。
Global Doubt
The kind you can't step out of and thus can't check.
罗素： 5 Minute Hypothesis. 如果世界只是诞生于5分钟以前？ 只是被设计的像是很久以前就存在的，来欺骗人类？
罗素的问题： 这重要吗？
笛卡尔认为是正确的。
Radical Skepticism
We really can't trust any of our beliefs
在一切都不可信的时候，唯一可信的是我正在思考。
Cogito ergo sum--- Meditations on First PhilosophyI think, therefore, I am.
笛卡尔相信的最基本的两条真理：
$\Rightarrow$我们的有些思想是清楚而明确的，能以某种方式自证其正确性。
最后推出不会有存在有能力制造出欺骗所有人的假象。
笛卡尔的反对者认为 我思故我在 是一个死胡同。
对怀疑主义的答复有两种:
John Locke:
我们出生时都是白板，所有知识都由经验获得。
We're born knowing nothing . And instead, all of our knowledge comes to us through sense data .
如何认识物质世界？
Primary Qualities
Qualities that physical objects themselves have.
Secondary Qualities
Our senses
The distinction between primiary and secondary qualities explained the disagreements that we all have about our perceptions of the outside world .
Irish philosopher George Berkeley:
无法发现任何第一性质而同时不考虑第二性质。 无法抽离第二性质而只考虑第一性质。
Secondary qualities are not objectively real. They can only be subjectively perceived .
$\Rightarrow$ There's just no such thing as matter . Instead, There's only perceptions .
Esse est percepi---George BerkeleyTo be is to be perceived
God is the ultimate perciver.
Assertion
A linguistic act --- either spoken or writen --- that has a truth value .
Truth Value
The state of being either true , or false, or indeterminate .
All declarative sentences (陈述句) have truth values. Declarations that assert something about the past or present are either true or false. Assertions about the future are indeterminate .
Proposition
The content of your assertion. The underlying meaning of what you're saying.
Belief
Propositional attitude of truth .
Knowledge
(Traditional Definition) Jusified true belief.
Justification
Evidence , or other support, for your belief .
kinds of justification:
Situtaions in which one can have jusified true belief , but not knowledge .
e.g. 你看见了草原上有一只羊，但它其实是一条狗，而草原上你看不到的地方确实有一只羊。 那么你有 证实为真的信念 ，这却并不是__知识__ 。
Karl Popper, 1902
使用可证伪性区分科学与伪科学。
Anselm 认为上帝的存在是可以证明的
ontology & ontological arguments
God is that than which no greater can be conceived. --- Anselm
Something can exist only in our minds and be strictly imaginary --- like santa, or unicorns. Or it can exist in our minds but also in reality , linke pizza and horses --- something that we can imagine, but that's also real.
犯了乞题谬误(循环论证)。
康德：一个物体存在并不是 predicate 。