The logic of intentional objects. A Meinongian version of classical logic
This book investigates intentionality, which is one of the most frequently discussed topics in contemporary phenomenology and analytic philosophy, from the ontological viewpoint of intentional objects by Austrian philosopher Alexius Meinong. The philosopher's ontology covers not only ordinary existing individuals but various kinds of non-existents like ``the round square'' or ``Sherlock Holmes'' for example, as well as non-individuals including such quantifier objects as ``some dog'' or ``every dog''. The author first explains how names, i.e. constant symbols for intentional objects, and quantifiers can share the same category in a formal language from their linguistic aspects rather than from their logical ones. Then a logic of intentional objetcs called Meinongian version of classical logic, or M-logic, is provided according to these considerations on intentional objects based on Meinong's idea. M-logic is a simple variation of the usual classical first-order predicate logic. In fact, it is built up on the same alphabet as classical logic with constant symbols and equality (without function symbols). However, constant symbols are dealt with as generalized quantifiers, so that formulas for the logic include those which can not be expressed in the usual first-order language. M-logic, introduced syntactically, is also shown to be characterized by a semantics based on the idea of so-called bundle theory for objects, that is, interpreting a constant symbol as a set of subsets of the domain over which individual variables range. On this formal setting of logic for intentional objects the author discusses several philosophical problems related to intentionality from the two aspects of syntax and semantics, and introduces such variants of M-logic as a free logic version, a modal logic version, and so on. On the one hand, M-logic is used as a tool for investigating formal features of intentional objects. On the other hand, the study of intentionality phenomena suggests further ways of extending and modifying M-logic. Thus formal investigations are intertwined with philosophical analyses in this book. A reader who studies intentionality from a traditional approach of philosophy will be interested in applying the method of formal analysis to his particular problems. For a logician who is not so familiar with philosophical problems on intentionality the book must help him to know aspects of intentionality in which philosophers are interested. Or a linguist who deals with formal languages may read the problems discussed here as those underlying the difficulty of a formal treatment of natural language. The book is addressed to logicians, cognitive scientists, philosophers of language and metaphysics with either a phenomenological or an analytic background.
scientific article; zbMATH DE number 1435802