This book, one of the first full-length studies of the modalities to emerge from the debate to which Saul Kripke, David Lewis, Ruth Marcus, and others are contributing, is an exploration and defense of the notion of modality de re, the idea that objects have both essential and accidental properties. Plantinga develops his argument by means of the notion of possible worlds and ranges over such key problems as the nature of essence, transworld identity, negative existential propositions, and the existence (...) of unactual objects in other possible worlds. He also applies his logical theories to the elucidation of two problems in the philosophy of religion: the problem of evil and the ontological argument. (shrink)

This essay catalogues the varieties of intentional entailment and systematically explores the relationships between them, giving particular attention to the intentional entailments used by Roderick Chisholm. Various principles of "realistic" doxastic logic are evaluated and provisional axiomatizations of intentional entailment are proposed. Then it is argued that there are doxastically non-contingent propositions--propositions that can't be believed or that must be believed--and that these create "paradoxes" of doxastic implication that are analogous to the "paradoxes" of strict implication. Many significant counterexamples are (...) generated by the paradoxes. (shrink)