本論文的目的在於探討麥可．泰所提出的真值間隙理論是否需要第三個語意值？基本上，我認為在泰的新構想中，第三值所扮演的角色是曖昧不明的，因為他一方面想要放棄第三值能夠處理含混性的想法，另一方面又肯定有第三值的想法。我認為泰保留第三值的想法可能來自兩個預設，一是模糊情況的預設（BCP），另一則是含混對象的預設（VOP），不過，我認為這兩個預設都無法提供第三值成立的理由。因為超值邏輯與知態邏輯皆顯示即使沒有第三值，我們也可以透過函映的方式處理真值間隙。另外，從集合論的觀點來看，承認含混對象也不必然要第三值。因此，除非泰能夠提出上述兩個預設以外的理由，否則在真值間隙理論中，第三值顯然是多餘的。
In this paper, I want to explore whether the novel truth-value gap theory on vagueness which was proposed by Michael Tye need to take the third semantic value different from being true and false or not? Basically, I thought that the role of third value is indeed opaque in his theory. One the one hand, Tye contended that it is impossible to deal with vagueness in terms of the third semantic value, namely indefinite, but on the other hand he ipso facto did not give up the third value in his account on vagueness. Eventually, Tye denied that the truth-value gap could be identical with the third value but due to there is no determinate fact of the matter about where there are sentences that are neither true, indefinite, nor false. I consider that Tye retained the third value might be in virtue of two main postulates, the first one is so-called borderline cases postulate (BCP) and the other one is vague objects postulate （VOP）. Unfortunately, I suggest that neither these two postulates are able to demonstrate the maintenance of the third value. First of all, the supervaluationism and epistemic theory showed that even there are borderline cases, the third semantic is not necessary for the construction of truth-value gap. In the next place, from a set-theoretical point of view the vague objects postulate could be consistent with classical logic. Thus, in Tye's truth-value gap theory, if there is no further reason besides BCP and VOP, the third semantic value seems to be redundant.
