Identity is a unique and interesting relation. To understand
what modalism is, and in some cases to follow what philosophers
who discuss the Trinity are getting so excited about, one needs
to be clear about the concept of identity. What follows is a
quick primer; for more, see section 2 of this article. In logic,
we express the claim that two (really “two”) things are
identical by putting the “=” symbol between their names (here,
a, b, c – these are names like “Bob”, not variables that take a
numerical value). When “a” refers to George W. Bush, and “b”
refers to Koko the Gorilla, these would be true: a=a, b=b. But
these would be false: a=b, b=a. Identity is a relation which is
- transitive. If a = b, and b = c, then also, a = c. (In this,
it is like the relations bigger than, or smarter than.) -
symmetrical. If a=b, then also, b=a. (In this, identity is like
the relation near to, and unlike the relation father of.) -
reflexive. Identity is a relation that a thing can only bear to
itself. Unlike most relations