Abstract

In this dissertation, I discuss how each individual's mental world is represented and shared with others. We understand and use a concept or the meaning of a general term to identify the objects falling under the term. There are two distinct approaches to research on the problems of concepts and meaning: the psychological approach and the formal approach. My major concern is to consider the possibility of reconciling these two different approaches, and for this I propose a psychologically plausible formal framework of conceptualization. ;Within the proposed framework I develop a theory-based account of concepts and explain how an agent activates a perspective in response to a situation in which reasoning using a concept is called for. Theories are represented as sets of facts and rules, both strict and defeasible and each theory is organized in a coherent perspective which stands for an agent's mental state or an agent's model of another agent's perspective. ;In my analysis of perspectival representation, I discuss how my notion of perspective is related to other mental phenomena such as consciousness and intentionality. Through a critique of Searle, I clarify some important properties of mental processes. Examining his connection principle and his notions of consciousness and intentionality, I augment his notion of Background, arguing that my notion of perspective replaces the Background in Searle's sense. ;My computational and philosophical account of perspectives and theories withstands evaluation from the empirical point of view represented by recent psychological studies. This investigation initiates a new research program in psychology, the study of perspectival cognitive processes. My notion of perspectival cognitive process is explained in the context of recent neuropsychological models suggesting a new way to interpret my notion of deep-level perspectival representation. Furthermore, Mangan's functional analysis of fringe phenomena and Baars's Global Workspace theory can be expanded to take into account how perspectival processes bridge the gap between conscious and unconscious processes