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### Single Idea 12830

#### [catalogued under 4. Formal Logic / G. Formal Mereology / 2. Terminology of Mereology]

Full Idea

The 'Universe' in mereology is the sum of all objects whatever, a unique individual of which all individuals are part. This is denoted by 'U'. Strictly, there can be no 'empty Universe', since the Universe is not a container, but the whole filling.

Gist of Idea

Universe: the mereological sum of all objects whatever, written 'U'

Source

Peter Simons (Parts [1987], 1.1.09)

Book Reference

Simons,Peter: 'Parts: a Study in Ontology' [OUP 1987], p.15

A Reaction

This, of course, contrasts with set theory, which cannot have a set of all sets. At the lower end, set theory does have a null set, while mereology has no null individual. See David Lewis on combining the two theories.