The Unmovable First Mover

Aristotle's Theory of the "For Something" in Nature

Aristotle thinks that specific behavior (behavior common to the species) has a teleological explanation. It happens "for something and because it is better" (Physics II.8.198b).

The details of Aristotle's teleology are not always easy to see, but the general idea is relatively straightforward. Consider the way human beings develop. Aristotle thinks that induction is "for something," reason, and happens "because it is better" for human beings to have reason. It is not a coincidence that induction happens regularly in human beings and that it makes them better. Aristotle thinks that human beings acquire reason in induction because this is how they become like the first unmovable mover. Its existence is good, and induction is a way human beings come to have an existence like the existence of the first unmovable mover.

Aristotle develops his teleology against the background of Plato's teleological explanations in the Timaeus. Aristotle, however, as has become clear, is both Platonist and Platonic critic. He accepts the Platonist framework and tries to correct what he regards as Plato's mistakes.

Teleological Causation without a Divine Maker

"[E]verything which becomes must of necessity become owing to some cause .... [W]hen the artificer (δημιουργὸς) of any object, in forming its shape and quality, keeps his gaze fixed on that which is uniform, using a model of this kind, that object, executed in this way, must of necessity be beautiful; but whenever he gazes at that which has come into existence and uses a created model, the object thus executed is not beautiful. Now the whole heaven (πᾶς οὐρανὸς), or cosmos (κόσμος), or if there is any other name which it specially prefers, by that let us call it,—so, be its name what it may, we must first investigate concerning it that primary question which has to be investigated at the outset in every case,—namely, whether it has existed always, having no beginning of generation, or whether it has come into existence, having begun from some beginning. It has come into existence; for it is visible and tangible and possessed of a body; and all such things are sensible, and things sensible, being apprehensible by opinion with the aid of sensation, come into existence, as we saw, and are generated. And that which has come into existence must necessarily, as we say, have come into existence by reason of some cause. Now to discover the maker and father (ποιητὴν καὶ πατέρα) of this universe were a task indeed; and having discovered him, to declare him unto all men were a thing impossible. However, let us return and inquire further concerning the cosmos,—after which of the models did its architect construct it? ... [I]t is clear to everyone that his gaze was on the eternal; for the cosmos is the fairest of all that has come into existence, and he the best of all the causes" (Timaeus 28a). In the Timaeus, Timaeus, not Socrates, leads the discussion. He "has made it his special task to learn about the nature of the universe" (Timaeus 27a). In this discussion, Timaeus argues for the existence of a divine maker (the "artificer" or "demiurge" (δημιουργὸς)) who is good and who arranges things so that everything in the cosmos is as like himself as possible.

"He [the divine maker] was good, and in him that is good no envy ariseth ever concerning anything; and being devoid of envy he desired that all should be, so far as possible, like unto himself. This, then, we shall be wholly right in accepting from men of wisdom as being above all the supreme originating principle (ἀρχὴν) of becoming and the cosmos" (Timaeus 29d).


"Let us conclude our discussion of the auxiliary causes that gave our eyes the power they now possess. We must next speak of that supremely beneficial function for which the god gave them to us. As my account has it, our sight has proved to be a source of supreme benefit to us, in that none of our present statements about the universe could ever have been made if we had never seen any stars, sun or heaven. The ability to see the periods of day-and-night, of months and of years, of equinoxes and solstices, has led to the invention of number, and has given us the idea of time and opened the path to inquiry into the nature of the universe. These pursuits have given us the love of wisdom, a gift from the god to the mortal race whose value neither has been nor ever will be surpassed. This is the supreme good our eyesight offers us. ... The god invented sight and gave it to us so that we might observe the orbits of intelligence in the universe and apply them to the revolutions of our own understanding. For there is a kinship between them, even though our revolutions are disturbed, whereas the universal orbits are undisturbed. So once we have come to know them and to share their ability to make correct calculations according to nature, we should stabilize the straying revolutions within ourselves by imitating the completely unstraying revolutions of the god" (Timaeus 46e).
One way the divine maker ensures that human beings are like him and thus are good is by ensuring that human beings have the sense of sight. It is through the exercise of this ability they can make themselves better by making their minds more orderly. Seeing is part of a process that gives rise to the love of wisdom and that ultimately transforms human beings so that their thinking "imitat[es] the completely unstraying revolutions of the god"

This teleological explanation in the Timaeus for why human beings have the sense of sight is like Aristotle's idea that human beings acquire reason for the sake of becoming like the first unmovable mover. Aristotle, however, takes the divine maker out of the explanation.

In the Metaphysics XII, Aristotle argues that there can be no first or last moment of time, that time is an attribute of change, and that the ultimate cause of the changes that occur in the universe (such as the development of reason in induction) must be free from the possibility of change. Otherwise, according to Aristotle, "if its substance is potentiality; for there will not be eternal motion, since that which exists potentially may not exist" (Metaphysics XII.1071b).

This conception of time and change seems to rule out a teleological explanation of things in terms of divine maker understood on the model of an "artificer" (δημιουργὸς), but Aristotle does not think that this conception makes teleological explanation itself impossible. In the place of the divine maker of Plato's Timaeus, Aristotle thinks that "the first mover, which does not move" (τὸ πρῶτον κινοῦν ἀκίνητον) is the starting-point for teleological explanation.

"[T]here is something which moves without being moved (ἔστι τι ὃ οὐ κινούμενον κινεῖ); something eternal which is both substance and actuality" (Metaphysics XII.7.1072a).

Teleological Causation in Aristotle's Universe



The Fixed Stars:

Most of the visible objects in the night sky appear to move together in the same relative arrangement night after night. These objects are the fixed stars. They appear to lie on a spherical surface surrounding the earth and to rotate about the north-south axis once per sidereal day.

A sidereal day is (a day relative to the stars) is the time it takes for the earth to rotate once on its axis so that the fixed stars appear to return again their prior positions. A sidereal day is about four minutes shorter than a solar day.

The Wandering Stars:

Relative to the fixed stars, some of the visible objects (the planets) appear to change their position. They are the "wandering stars" (ἀστέρες πλανῆται). In terms of spheres, their apparent motion is more difficult to explain.

One change that Aristotle explains teleologically is the motion of the fixed stars in the heavens. These stars move with a continuous circular motion, and the first unmovable first mover is the teleological cause of this motion. It causes this change in the stars without itself changing.

Just what Aristotle thought constitutes this teleological causation is not completely clear, but his idea seems to be that eternally moving in a circle is a behavior that belongs to the stars because this is the way their existence is like the existence of the first unmovable mover.

"Since we have seen that there are three kinds of substance, two of which are natural and one immutable, we must now discuss the last named and show that there must be some substance which is eternal and immutable. Substances are the primary reality, and if they are all perishable, everything is perishable. But motion cannot be either generated or destroyed, for it always existed; nor can time, because there can be no priority or posteriority if there is no time. Hence as time is continuous, so too is motion; for time is either identical with motion or an affection of it. But there is no continuous motion except that which is spatial, of spatial motion only that which is circular" (Metaphysics XII.7.1071b). "The first heaven, then, must be eternal, and something must move it. And since that which is moved and moves is intermediate, there is a mover which moves without being moved, being eternal, substance, actuality" (Metaphysics XII.7.1072a).

In the realm below the stars and heavenly bodies, natural bodies have ways other than continuous circular motion of naturally becoming like the first unmovable mover.

Induction is an example. It is caused teleologically. Unlike in the Timaeus, a divine "artificer" does not arrange things so that human beings have the sense of sight and thus that their thinking becomes like "the completely unstraying revolutions of the god." Instead, for Aristotle, acquiring reason in induction is a way human existence naturally becomes like the existence of the first unmovable mover. Acquiring reason and its knowledge is a step in the direction of the "contemplation" (θεωρία) that characterizes the existence of the first unmovable mover.

"Such, then, is the starting-point upon which the heaven and nature depend. Its life is like the best which we temporarily enjoy. It must be in that state always, which for us is impossible.... Actuality is thought to be the intellect (νοῦς) the divine possesses, and contemplation (θεωρία) is that which is most pleasant and best. ... If, then, the state the god (ὁ θεὸς) always enjoys is as great as that which we enjoy sometimes, it is marvelous; and if it is greater, this is still more marvelous. Nevertheless it is so. Moreover, life belongs to god. For the actuality of intellect is life, and god is that actuality; and the essential actuality of god is life most good and eternal. We hold, then, that god is a living being, eternal, most good" (Metaphysics XII.7.1072b).

The Existence of an Actuality with Qualification

"First, then, we must speak of food and reproduction; for the nutritive soul belongs to all other living creatures besides man, and is the first and most widely shared faculty of the soul, in virtue of which they all have life. Its functions are reproduction and the assimilation of food, as a living thing that has reached its normal development and is unmutilated, and whose mode of generation is not spontaneous, naturally produces another like itself, an animal producing an animal, and a plant a plant, in order that, as far as its nature allows, it may partake in the eternal and divine (τοῦ ἀεὶ καὶ τοῦ θείου). Each strives for this and for the sake of this performs all its natural functions. ... However, since they cannot share in the eternal and divine by continuity of existence, because no perishable thing can remain numerically one and the same, they share in these in the only way they can, some to a greater and some to a lesser extent; what persists is not the individual itself, but something in its image, not one in number but one in form" (One the Soul II.4.415a). Given this understanding of Aristotle's teleology, it is a little clearer why the soul, as the form of a living natural body, is a "first actuality" (On the Soul II.1.412a).

As the form, the soul is the cause of the activity that constitutes the life of these bodies. Because this activity is different at different times, the soul is not a "full, complete reality" and so not an actuality without qualification. It is, however, an actuality because the activity is an existence that with qualification is the "complete, full" existence the unmovable first mover enjoys.

Even so Aristotle's idea remains difficult to understand. The perfect existence that characterizes the unmovable first mover is unclear, and the various ways living bodies function do not seem to stand in a very natural relationship to the existence of the unmovable first mover.

Consider the fixed stars in the first heavens. Their existence is one of eternal continuous circular motion. This motion is how the stars change to be like the perfect and unchanging existence that characterizes the unmovable first mover. The first unmovable mover is a teleological cause this change in the stars. It itself does not move. The stars move to be like it.

Consider induction in human beings. As they mature from children into adults, they develop reason. This is how human beings naturally change to have an existence that is like the perfect and unchanging existence that characterizes the unmovable first mover. The first unmovable mover is a teleological cause of induction in human beings. It itself does not change. Human beings naturally undergo induction to become like the first unmovable mover.




Perseus Digital Library:

Plato, Timaeus.
Aristotle, Metaphysics.

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
κόσμος, kosmos, noun, "order"




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