Intensional Kleene logics for vagueness
Nicolò Zamperlin

Abstract:
In this thesis we study the phenomenon of vagueness using multi-valued logics. First, we develop a collection of logics based on strong and weak Kleene truth-tables. All these logics are tolerant, they can express a change in degree for some property which is too small to be perceived as significant by a competent speaker. In classical logic this form of tolerance brings to the sorites paradox. The logics developed in the thesis can account for tolerance while retaining their consistency. These logics are also intensional, since they make use of non-rigid terms and intensional objects.
Two among the defined logics are chosen in order to study the notion of vagueness that they convey and how they can account for problematic subjects, such as vague objects and vague identity. Finally, we provide two interpretations of vagueness, an epistemic one based on Kantian epistemology, and one in a discursive setting using the notion of topic.