184 ARGUMENTS: MONOTHEISTIC CONCEPTIONSactions. Semitic and Hindu monotheists want to infer from the world’s
existence to God’s existence in a way that does require that God has chosen to
create and that God created (the choice and the act may be the same). Even if a
monotheist does not think that you can successfully infer from the world’s
existence to God’s existence, she typically will have a view about how the
world is related to God. Ramanuja, for example, rejects any inference from the
world’s existence to God’s existence, but holds that the world is everlastingly
dependent for its existence on God. Among the most famous and influential of
arguments for monotheism are Aquinas’s Five Ways.
Arguments by Thomas Aquinas
Aquinas’s arguments are of considerable historical interest. For our present
purposes, however, three questions matter: (i) do any of his arguments prove
their intended conclusion?; (ii) if not, can one learn from them how to frame a
more powerful argument for their intended conclusion or something much like
it?; (iii) do his arguments suggest some other approach to the question of the
truth or falsity of monotheism? Questions (i) and (ii) are considered in this
chapter; the third receives attention in the later chapter on Faith and Reason.
Aquinas asks whether the existence of God can be proved and answers in the
affirmative. He then offers five arguments for God’s existence followed by an
argument that the being referred to in the conclusion of the first argument is
the same as that referred to in the conclusion of each of the other arguments.
Here, too, beginning with a few definitions will enable us to state complex
arguments with much greater simplicity than we could without them.
Reflexive and irreflexive relations
Aquinas’s arguments deal with certain relationships he takes to hold between
one thing in the world and another thing in the world, or between the world
and God. Here are some fundamental features of relations:^13
Definition 1: Relation R, holding between X and Y, is reflexive if X has
R toY entails Y has R to X.
If Jack is the same height as Jill, then Jill is the same height as Jack; being the
same height as is a reflexive relation.
Definition 2: Relation R, holding between X and Y, is irreflexive if X
has R toY entails Y does not have R to X.