The Prime Mover

Since everything that is in motion must be moved by something, let us suppose there is a thing in motion which was moved by something else in motion, and that by something else, and so on. but this series cannot go on to infinity, so there must be some first mover.
- Aristotle, Physics

Must there have been a first mover, that started the universe moving?

Aristotle, unlike Plato, accepted the reality of motion and change, and he developed his doctrine of the Four Causes to explain them. but Aristotle reasoned that, since everything that moves is moved by something else, there must have been a First Mover which started all motion in the first place. And this First Mover, though it moves everything else, cannot itself be moved (or it wouldn't be the First Mover).

Furthermore, since without change there can be no time, this Prime Mover is eternal-outside time. And since it is eternal, it is not material, for material things all have the potentiality for change, and the Prime Mover is changeless. Being non-material, it takes up no space. So how can such a being move the whole universe? How can a thing cause motion without itself being moved?

Aristotle employs the analogy of a lover and his beloved. The beloved is not moved, but the lover is moved by being drawn toward his beloved. In the same way, the Prime Mover moves the world by being the object of its desire. Love makes the world go round! How does this work? Consider the student who studies diligently now in order to gain a reward in the future. The future goal, though immaterial, reaches into the past and shapes the student's present behavior.

But what does this Prime Mover do? If it is actual-- which it must be, otherwise there'd be no motion--it must occupy itself somehow. Aristotle reasons that, since it is eternal and immaterial, the Prime Mover's activity must be pure thought. And since it is perfect, it must think only of the purest thing-- which is itself. So God, or the Prime Mover, is pure thought thinking about itself.

Is it true that there must be a Prime Mover, a First Mover? Why couldn't there be an infinite series of material movers? Why not conclude that there has always been motion?

Bibliography

Aristotles The Basic Works, Random House, New York, 1941. See the Metaphysics and the Physics.

McKeon, Richard, editors, Introduction to Aristotle, The Modern Library, New York, 1947.