## A (Leibnizian) Theory of Concepts

### Author

Edward N. Zalta
### Reference

*Philosophiegeschichte und logische Analyse* /
*Logical Analysis and History of Philosophy*, **3**
(2000), pp. 137-183
### Abstract

In this paper, the author develops a theory of concepts and shows that
it captures many of the ideas about concepts that Leibniz expressed in
his work. Concepts are first analyzed in terms of a precise
background theory of abstract objects, and once concept summation and
concept containment are defined, the axioms and theorems of Leibniz's
calculus of concepts (in his logical papers) are derived. This
analysis of concepts is then seamlessly connected with Leibniz's modal
metaphysics of complete individual concepts. The fundamental theorem
of Leibniz's modal metaphysics of concepts is proved, namely, whenever
an object x has F contingently, then (i) the individual concept of x
contains the concept F and (ii) there is a (counterpart) complete
individual concept y which doesn't contain the concept F and which
`appears' at some other possible world. Finally, the author shows how
the concept containment theory of truth can be made precise and made
consistent with a modern conception of truth.

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