Edward Zalta

The author resolves a conflict between Frege's view that the cognitive significance of coreferential names may be distinct and Kaplan's view that since coreferential names have the same "character", they have the same cognitive significance. A distinction is drawn between an expression's "character" and its "cognitive character". The former yields the denotation of an expression relative to a context (and individual); the latter yields the abstract sense of an expression relative to a context (and individual). Though coreferential names have the same character, they may have distinct cognitive characters. Propositions involving these abstract senses play an important role in explaining de dicto belief contexts.

In this paper, the author derives the Dedekind-Peano axioms for number theory from a consistent and general metaphysical theory of abstract objects. The derivation makes no appeal to primitive mathematical notions, implicit definitions, or a principle of infinity. The theorems proved constitute an important subset of the numbered propositions found in Frege's *Grundgesetze*. The proofs of the theorems reconstruct Frege's derivations, with the exception of the claim that every number has a successor, which is derived from a modal axiom that (philosophical) logicians implicitly accept. In the final section of the paper, there is a brief philosophical discussion of how the present theory relates to the work of other philosophers attempting to reconstruct Frege's conception of numbers and logical objects.

This paper contains answers to the following Five questions, posed by the editors are answered: (1) Why were you initially drawn to the foundations of mathematics and/or the philosophy of mathematics? (2) What example(s) from your work (or the work of others) illustrates the use of mathematics for philosophy? (3) What is the proper role of philosophy of mathematics in relation to logic, foundations of mathematics, the traditional core areas of mathematics, and science? (4) What do you consider the most neglected topics and/or contributions in late 20th century philosophy of mathematics? (5) What are the most important open problems in the philosophy of mathematics and what are the prospects for progress?

The author examines the differences between the general intensional logic defined in his recent book and Montague's intensional logic. Whereas Montague assigned extensions and intensions to expressions (and employed set theory to construct these values as certain sets), the author assigns denotations to terms and relies upon an axiomatic theory of intensional entities that covers properties, relations, propositions, worlds, and other abstract objects. It is then shown that the puzzles for Montague's analyses of modality and descriptions, propositional attitudes, and directedness towards nonexistents can be solved using the author's logic.

A. Plantinga develops a challenging critique of Castañeda's guise theory, by identifying fundamental intuitions that guise theory gives up and by developing several objections to the guise-theoretic world view as a whole. In this paper, I examine whether Plantinga's criticisms apply to the theory of abstract objects. The theory of abstract objects and guise theory can be fruitfully compared because they share a common intellectual heritage---both follow Ernst Mally [1912] in postulating a special realm of objects distinguished by their "internal" or "encoded" properties. Despite this common heritage, however, the theories organize, develop, and apply these special objects in distinctive ways. The two metaphysical systems, therefore, differ significantly, and these differences become important when one considers Plantinga's critique of guise theory. In this essay, the author shows that the theory of abstract objects anticipates and addresses most of Plantinga's concerns about guise theory, by preserving intuitions guise theory has abandoned.