誠實方為上策？—康德論說謊

Abstract

本文以康德〈論因慈善的動機而說謊的虛妄權利〉一文中的殺人兇手案例為焦點，旨在探討在康德倫理學的脈絡中，此時對兇手說謊的行為是否具有道德正當性，藉以評論康德倫理學稱為嚴格主義是否合理。 本文首先說明康德對說謊的定義，以及「不可說謊」座落於康德倫理學中何種義務類型之下。接著本文轉而討論定言令式的三條公式：普遍法原則、目的原則與目的王國原則，探討這三條公式是如何被運用來判斷說謊的道德性質。普遍法原則揭露出道德法則的形式；經過詮釋後，本文指出普遍法原則中的「普遍」二字必須經過適當的限縮，因而此原則允許在殺人案例的情況下對別人說謊。目的原則和目的王國原則顯示了道德所要保護的價值，本文指出在康德倫理學中，蘊涵了發展自身與促進整體和諧的人性概念是最需要受到保護的絕對價值；在這樣的理解下，本文試圖論證說謊並非總是傷害人性，進而主張此時說謊是道德上可允許的行為。 接著本文開始建構康德倫理學中道德判斷的機制，不同的理由可能形成互相衝突的道德法則，但實際上只有最具說服力的理由才足以成為道德法則的根據。回到殺人兇手的例子上，根據先前的討論，定言令式的三條公式都肯定此時說謊並不違反道德法則的要求。且在參照過康德不同的著作以後，可以發現康德倫理學確實承認說謊在某些情況下具有正當性，因此康德在〈論因慈善的動機而說謊的虛妄權利〉文中的主張並不正確。

This thesis concentrates on the moral status of lying in Kantian ethics. In his article “On a Supposed Right to Lie from Philanthropy”, Kant claims that lying is morally forbidden in any circumstance. However, taking Kantian ethics as a whole, I will argue that lying is sometimes morally permissible. Therefore, to describe Kantian ethics as “rigorism” is inadequate.   In Chapter 1, I will introduce Kant’s definition of lying, and the categories in which the duty of “Do not lie” is located. In Chapters 2 to 5, I will focus on the three formulae of the Categorical Imperative, FUL, FH and FRE, to discuss how these formulae are applied to evaluate the moral status of lying. In my interpretation, the concept of “universalization” in FUL should be reinterpreted to be the principle of consistency. Thus lying to the murderer can pass the test of FUL and is morally permissible. I will also argue that in FH and FRE the absolute value that Kantian ethics wants to protect is humanity, which implies the concept of self developing and of promoting the harmony of the unity. By this interpretation, lying to the murderer is also morally permissible, since lying in this case does not degrade humanity.  In conclusion, I will claim that these three formulae, which are seen as the different aspects of the same Categorical Imperative, converge to the same position that acknowledges the moral permissibility of lying in murderer-at-the-door case. Examining the other writings of Kant, it can also be found that he acknowledges the moral legitimacy of lying in some situations. Therefore, Kant’s claim in “On a Supposed Right to Lie from Philanthropy” is incoherent with his ethical theory. In Kantian ethics, at least in the murderer-at-the-door case, lying is a morally permissible action.