# Abstract object theory

**Abstract object theory** (**AOT**) is a branch of metaphysics regarding abstract objects.^{[1]} Originally devised by metaphysician Edward Zalta in 1981,^{[2]} the theory was an expansion of mathematical Platonism.

*Abstract Objects: An Introduction to Axiomatic Metaphysics* (1983) is the title of a publication by Edward Zalta that outlines abstract object theory.

AOT is a dual predication approach (also known as "dual copula strategy") to abstract objects^{[3]}^{[4]} influenced by the contributions of Alexius Meinong^{[5]}^{[6]} and his student Ernst Mally.^{[7]}^{[6]} On Zalta's account, there are two modes of predication: some objects (the ordinary concrete ones around us, like tables and chairs) *exemplify* properties, while others (abstract objects like numbers, and what others would call "non-existent objects", like the round square, and the mountain made entirely of gold) merely *encode* them.^{[8]} While the objects that exemplify properties are discovered through traditional empirical means, a simple set of axioms allows us to know about objects that encode properties.^{[9]} For every set of properties, there is exactly one object that encodes exactly that set of properties and no others.^{[10]} This allows for a formalized ontology.

A notable feature of AOT is that several notable paradoxes in naive predication theory (namely Romane Clark's paradox undermining the earliest version of Héctor-Neri Castañeda's guise theory,^{[11]}^{[12]}^{[13]} Alan McMichael's paradox,^{[14]} and Daniel Kirchner's paradox)^{[15]} do not arise within it.^{[16]} AOT employs restricted abstraction schemata to avoid such paradoxes.^{[17]}

In 2007, Zalta and Branden Fitelson introduced the term **computational metaphysics** to describe the implementation and investigation of formal, **axiomatic metaphysics** in an automated reasoning environment.^{[18]}^{[19]}