康德

純粹理性批判

主題：形上學的可能性

形上學對康德而言是指獨立於經驗的理性所追尋的認知，於是形上學便攸關先驗知識，
也就是其知識的證成並非來自經驗。然後他將先驗知識與理性結合起來。
所謂形上學的可能性也就是回答「人類理性如何達成先驗知識？」的問題。

歷史脈絡：啟蒙運動的危機
（１７８０年代正是啟蒙運動即將轉向浪漫主義的關鍵期）

啟蒙運動是對現代科學在十五、十六世紀的興起與盛行的反應。從牛頓的成就以來，就充斥著人類理性能駕馭自然的自信與自傲。這使得在科學之前解答人的問題的權威（神學、宗教）成為問題。

傳統的權威－＞個人自身理性的權威

啟蒙運動的危機：當時以機械論式的物理學為主流。要是整個自然的運作都受機械論、因果律所支配，那麼似乎就不存在所謂的自由或不朽靈魂。這顯然牴觸了「道德需要自由」的傳統觀點（一個人必須是自由的才能從對與錯中選擇，否則一個人無須為自己的行為負責，也因而不具有道德責任）。啟蒙的理性樂觀帶來了人所不願意犧牲的自由的失去，這就是啟蒙運動的危機。

康德以純粹理性批判回應了啟蒙運動的危機。其主題是形上學，因為（對康德而言）形上學屬於理性的領域。康德的終極目的是展演出理性對自身的批判（既不偷渡傳統權威也不受傳統權威的限制），進而為牛頓的科學觀與道德與宗教提出一個相融貫的基礎。［康德仍固守啟蒙運動對理性的自豪，而不是承認啟蒙主義的失敗。康德的工作在於挽救啟蒙主義。］


人類認知的兩大功能(cognitive faculties)：感性(sensibility)與知性(understanding)


放棄對物自身的知識對於調和科學與宗教道德來說是必要的。

Restricting knowledge to appearances and relegating God and the soul to an unknowable realm of things in themselves guarantees that it is impossible to disprove claims about God and the freedom or immortality of the soul, which moral arguments may therefore justify us in believing. Moreover, the determinism of modern science no longer threatens the freedom required by traditional morality, because science and therefore determinism apply only to appearances, and there is room for freedom in the realm of things in themselves, where the self or soul is located. We cannot know (theoretically) that we are free, because we cannot know anything about things in themselves. But there are especially strong moral grounds for the belief in human freedom, which acts as “the keystone” supporting other morally grounded beliefs (5:3–4). In this way, Kant replaces transcendent metaphysics with a new practical science that he calls the metaphysics of morals. It thus turns out that two kinds of metaphysics are possible: the metaphysics of experience (or nature) and the metaphysics of morals, both of which depend on Kant's Copernican revolution in philosophy.

先驗觀念論(Transcendental Idealism)

人只能經驗到表象而不能經驗到物自身，時間與空間只是人類直觀的主觀形式。(見A42/B59-60, A369)


－In some sense, human beings experience only appearances, not things in themselves.
－Space and time are not things in themselves, or determinations of things in themselves that would remain if one abstracted from all subjective conditions of human intuition. [Kant labels this conclusion a) at A26/B42 and again at A32–33/B49. It is at least a crucial part of what he means by calling space and time transcendentally ideal (A28/B44, A35–36/B52)].
－Space and time are nothing other than the subjective forms of human sensible intuition. [Kant labels this conclusion b) at A26/B42 and again at A33/B49–50].
－Space and time are empirically real, which means that “everything that can come before us externally as an object” is in both space and time, and that our internal intuitions of ourselves are in time (A28/B44, A34–35/B51–51).

對先驗觀念論的兩種詮釋：two-objects interpretation / two-aspects interpretation (two-worlds interpretation / one-world interpretation)

two-objects interpretation: (Jacobi, Guyer, Strawson)
有可能導致現象論，將經驗的對象化約為心靈表象。

two-aspects interpretation: (Allison, Bird)

先驗演繹（Transcendental Deduction）

先驗演繹的目標在於顯示，我們有客觀有效的先驗概念，而且他們必然被應用於世界中我們所經驗的所有事物。也就是，範疇是經驗的必要條件。

康德將試圖說明，範疇對於自我意識(以Leibniz的術語來說即是apperception)來說尤其必要。

http://plato.stanford.edu/entries/kant/

http://plato.stanford.edu/entries/kant-reason/

http://plato.stanford.edu/entries/kant-metaphysics/