从逻辑哲学观点看含混性问题

The Problem of Vagueness: From a Viewpoint of Philosophy of Logic

当代哲学家们围绕含混性问题展开激烈争论,有许多的理论被相继提出和改进。这些理论相互竞争、彼此批评,我们却很难看出它们是否是关于相同现象的理论,而且坚守不同理论的哲学家实际上关于含混性问题有很少共识。本文借鉴苏珊·哈克的逻辑哲学思想,通过区分不同层次的含混性问题,分析各种含混性理论的动机、关切点和优劣,进而提供把握含混性问题及相关理论的一种整体视角。从逻辑哲学的观点看:(1)三值理论和模糊理论通过发明新的非经典逻辑系统来处理含混性问题;(2)超赋值论和次赋值论通过发明新的赋值语义学来解决含混性问题;(3)认知主义和语境主义通过添加"辅助假设"来维护和保留经典逻辑及其语义学;(4)表征主义和本体论的含混性主要关心含混语言与世界的关系,而不是含混性的逻辑。每种理论或多或少地包含逻辑、语言、认知和形而上学成分,分别强调含混性问题的不同方面。本文在最后指出自然类的研究有助于我们理解含混性的本性,并通过论证自然类的含混性来辩护本体论的含混性,主张含混性不仅仅是语言的和认知的,它在很大程度上反映了我们世界的本来面目。

There is a fierce debate concerning the problem of vagueness among contempo-rary analytic philosophers, and many theories of vagueness have been proposed and pro-moted. However, it is hard for us to tell whether these competing theories of vague-ness are concerned with the same phenomenon, and, as a matter of fact, there is little consensus about the problem of vagueness among philosophers who adhere to different theories of vagueness. Based on Susan Haack’s thoughts on philosophy of logic, this paper analyzes the motivation, emphasis and merits and disadvantages of each theory of vagueness, and tries to provide a comprehensive perspective on the problem of vague-ness and related theories by means of distinguishing different levels of issues. From a viewpoint of philosophy of logic, (i) three-valued theories and fuzzy theories attempt to resolve the problem of vagueness by inventing new non-classical logical systems;(ii) su-pervaluationism and subvaluationism try to solve the problem of vagueness by creating new valuation semantics;(iii) epstemicism and contextualism aim to preserve classical logics and classical semantics by adding‘auxiliary hypothesis’;and (iv) representation-alism and ontological vagueness mainly focus on the relation between vague language and the world rather than the logic of vagueness. Every theory of vagueness more or less contains logical, linguistic, epistemic and metaphysical components, concentrating on different aspect of this problem respectively. Finally, this paper points out that natural kinds may be helpful to our understanding to the nature of vagueness, and the author defends ontological vagueness by arguing for the vagueness of natural kinds which have ontological priority over individual objects. Vagueness is not just linguistic or epistemic, but to large extent reflects the fundamental structures of the world.