What is known to us as metaphysics is what Aristotle called
"first philosophy." Metaphysics involves a study of the universal
principles of being, the abstract qualities of existence itself.
Perhaps the starting point of Aristotle's metaphysics is his rejection
of Plato's Theory of Forms. In Plato's theory, material objects
are changeable and not real in themselves; rather, they correspond
to an ideal, eternal, and immutable Form by a common name, and this
Form can be perceived only by the intellect. Thus a thing perceived
to be beautiful in this world is in fact an imperfect manifestation
of the Form of Beauty. Aristotle's arguments against this theory
were numerous. Ultimately he rejected Plato's ideas as poetic but
empty language; as a scientist and empiricist he preferred to focus
on the reality of the material world.
Metaphysics, or the parts still in existence,
spans fourteen books. The early books give background information
and survey the field before Aristotle's time. He also describes
the nature of wisdom: it begins with sense perceptions, which must
be translated into scientific expertise. Such knowledge requires
the understanding of both facts and causes, and wisdom comes only
with an understanding of the universal principles and primary causes
built on this science. Aristotle's work in metaphysics is therefore
motivated by this desire for wisdom, which requires the pursuit
of knowledge for its own sake.
By the fourth book he begins to attack some of the sophistry
that has contaminated the field. One point that he dwells on is
the law of contradictions, which essentially asserts that something
cannot both be and not be at the same time. In particular, he is
concerned with the relativism and even nihilism that would result
from a metaphysics that allowed contradictions. The relationship
between form and matter is another central problem for Aristotle.
He argues that both are substances, but matter is potential, while
form is actual. The two are not separate but intertwined, and actuality
precedes potentiality. Although the actual is produced from the
potential, it is the actual that makes the production possible.
Several of the books covering topics like contrariety,
unity, the nature of mathematical objects, and others are usually
neglected, as they show less originality compared with the key
points of the Metaphysics. Book XII, on the other
hand, is usually considered the culmination of Aristotle's work
in metaphysics, and in it he offers his teleological system. Before
he draws any grand conclusions, he begins with the idea of substance,
of which there are three kinds: changeable and perishable (e.g.,
plants and animals), changeable and eternal (e.g., heavenly bodies),
and immutable. If all substances are perishable, then ultimate
destruction of everything is inevitable. But Aristotle asserts
two imperishable entities: motion and time. If time were created,
then there must have been no time before the creation, but the
very concept of "before" necessitates the concept of time. On the
other hand, as he argued in his works of natural philosophy, the
only continuous motion must be circular. Thus he returns to the
idea of the Unmoved Mover, for only such a being could generate
eternal circular motion. The Unmoved Mover is the ultimate cause
of the universe, and it is pure actuality, containing no matter
since it is the very cause of itself. In order for the Mover to
be unmoved itself, it must move in a non-physical way, by inspiring desire.
Aristotle gives the Mover the name of God, but this figure
is unlike most standard conceptions of a divine being. Though Aristotle
asserts that it is a living creature and represents the pinnacle
of goodness, it also has no interest in the world and no recognition
of man, for it exists in a completely transcendent and abstract
state. The activity of God–if it can be called such–is simply knowledge, and
this knowledge is purely a knowledge of itself, because an abstracted
being is above sense and experience and can know only what is best.
Some have interpreted this to mean that God, in knowing itself,
implicitly knows everything else, but Aristotle flatly denied this
view. In fact, he believed, for example, that God would have no
knowledge of evil. Thus Aristotle's conception is full of paradoxes.
God is the ultimate cause of everything in the world, but it also
remains completely detached.