Logic, Semantics, Ontology
Dissertation, Massachusetts Institute of Technology (
1991)
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Abstract
Logic, Semantics, Ontology consists of three papers concerned with ontological issues. The first, "That There Might Be Vague Objects", is a critical study of Gareth Evans's essay, "Can There be Vague Objects". The author argues that the formal argument presented in Evans's paper is valid and that a contradiction can indeed be derived from the statement that it is indeterminate whether a is b. However, the deduction theorem fails in the required logic: Hence, one can not derive the validity of the statement that it is determinate whether a is b. ;One who holds the view that there are vague objects is committed to the legitimacy of those principals to which appeal is required in the proof. Hence, the view that there are vague objects is committed to the claim that no statement of the form "It is indeterminate whether a is b" can be true, but also to denying the validity of its negation. Possible motivations for such a position are sketched and its tenability is defended. ;The second paper, "Whether Structure May Be Misleading", is a critical study of Crispin Wright's Frege's Conception of Numbers as Objects, in which Wright defends Platonism, the view that there areObjects of various sorts. The author argues that Wright's view is too promiscuous, that Wright's view appears to commit us to the existence of far too may sorts of objects. The causes of this ontological extravagance are isolated, and the author suggests ways to avoid it. In the process, however, the author also argues that certain classical Reductionist arguments fail and that their failure is closely connected with the strongest motivations for Platonism