#### Supplement to Actualism

## Plantinga's Definition of an Individual Essence

**Essential Properties**

A property *P* is *essential to* an individual
*x* if and only if it is not possible that *x* exist and
fail to exemplify *P*.

**Individual Essences**

A property *E* is an *individual essence of* an
individual *x* if and only if (i) *E* is essential to
*x* and (ii) necessarily, for all individuals *y*,
*y* exemplifies *E* if and only if *y* =
*x*. Hence, *E* is an individual essence, simpliciter, if
and only if it is possible that there be an individual *x* such
that *P* is an individual essence of *x*.

Note that, by the above definition, an individual could have several individual essences.