臺灣博碩士論文加值系統

人類透過語言傳遞知識。維根斯坦指出，人類透過語言來描繪並認識這個世界。亞理士多德則認為，當我們用語言表達某個判斷時，我們不只表達了一連串的字詞符號，更表達了釵h能呈現世界是怎麼樣的事物(items)。然而，我們的日常語言並不完美。它總是不乏模糊(vagueness)與歧義(ambiguity)，以致於當我們要判斷一個表達是否如實的呈現關於世界的某個事件時，我們所擁有的不完美的語言似乎又變成我們理解這個世界的障礙。此外，從謂述理論(theory of predication)的角度來看，當我們試圖藉助於排中律或二價律來解釋自然語言的謂述(predicating)過程時，這些模糊的表達(vague expression)反而卻造成古典邏輯的困挫。而在這之中，由含糊性所產生最著名的困難，便是堆垛悖論(sorites paradox)。
堆垛悖論是指，當一粒沙子並不足以成堆(a heap)時，則在此不足以成堆的沙上增加一粒沙並不會因此成推；同理，當我們在此無法成堆的沙上再加一粒沙，亦不會使它因此成堆……如此反覆推論下去則會得出一荒謬的結果：不論有多少的沙子均不足以成堆。我們可用堆垛悖論的數學歸納版本來表示—假設��(n)表示具有n根頭髮的人是禿子。當歸納前提��(0)成立(即：有0根頭髮的人是禿子)，且推論規則�px (��(x)→��(x+1))也成立時，卻會得出�px ��(x)，此處的x可以是任意大的數字，以致於具有十萬根頭髮的人仍是禿子。在這樣的論證中，前提��(0)為真，推論規則無誤，但卻會得出一明顯荒謬而不可接受的結果。對於這種由語意模糊性所產生的悖論，有些哲學家將之歸咎於語言本身的缺陷，認為應透過各種粹鍊純化的過程使語言更趨精準，進而消解悖論。但另一批哲學家則主張悖論源自於人類有限的認知能力尚不足以洞識某些有助於判斷模糊陳述的事實，而不在於語言的不精確性。他們認為透過接受這種知態上的限制(而非嘗試消除模糊性)，我們反而對外在世界能有更進一步的理解。
而本論文的目的正是要捍衛後者這種關於模糊性的知態理論(epistemicist theory of vagueness)。在第一章中，我將分析模糊性的根源與所產生的困難，並簡述各種可能的處理進路：這包括赫杰(Hajek)的程度理論/模糊邏輯(degree theory/ fuzzy logic)、超值主義(supervaluationalism)、知態觀點(epistemic view) 與虛無主義(nihilism)。在第二章中，我將更進一步檢視姬芙(Keefe)的超值主義，並論證姬芙將佛萊森(Fraassen)處理空名問題的超值(supervaluations)概念應用到處理語意模糊與堆垛悖論上不但不合法，甚至連她意圖透過精確化(precisification)來消除語意模糊這樣的動機勢必面臨兩難。在最後一章，我將討論對於威廉森(Williamson)知態主義常見的三種批判與反駁，並以回應杜爾(Dorr)與雷(Ray)分別在2003與2004年初新進的挑戰來達到證成知態主義的目的。

The aim of this thesis is to defend epistemicist theory of vagueness. In the first chapter, I shall analyze the genesis of vagueness and the problems that arise from borderline cases. I will also briefly introduce various approaches toward vagueness; these approaches include Williamson’s epistemicism, Hajek’s degree theory/fuzzy logic, Keefe’s supervaluationalism, and Unger’s nihilism. Next I will thoroughly examine Keefe’s (2000) supervaluationalism and argue that her attempt to apply van Fraassen’s supervaluations on empty name to vague expression is illegitimate. Moreover, her attempt to eliminate semantic vagueness simply misses the point. In the third chapter, I will focus on defending the epistemic view. I will also consider Schiffer’s (1999) and Keefe’s (2000) criticisms of Williamson’s strategy of explaining our ignorance and Mott’s (1998) accusation that the margin for error principle makes iteration of knowledge impossible. In addition, I will try to dispel challenges recently put forth by Dorr (2003), who suggests substituting unassertability with ignorance, and Ray (2004), who attempts to show that epistemicism is self-defeating through his three-way undermining. Last but not least, I will conclude that the epistemic view is the most promising theory of vagueness so far.

Abstract(i)
中文摘要(ii)

1 The Phenomena of Vagueness
1.1introduction (P.1)
1.2 Vagueness, truth-value gaps, and the sorites paradox(P.3)
1.3 Four reflections to the puzzle(P.7)

2 On Supervaluational account of vagueness
2.1 Supervaluations(P.15)
2.2 Objections from Williamson(P.20)
2.3 Objections from Dummett(P.24)


3 On epistemic View of Vagueness
3.1 Vagueness as ignorance(P.31)
3.2 Inexact knowledge and margin for error(P.35)
3.3 General Objections from Schiffer, Keefe, and Mott (P.40)
3.4 Dorr’s Challenges(P.44)
3.5 Ray’s Criticism(P.49)
3.6 Conclusion(P.54)

Appendix: Ray’s reformulation of Williamson’s master argument(P.58)

Reference(P.60)

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