Plato's Prime Mover Argument Plato, Laws, Book X In Book X Plato considers murder and other acts of violence acts one might think the gods would dislike and usually punish. Here the 'Athenian Stranger' (presumably, by and large, speaking for Plato) says that people who do this sort of thing either (1) believe that the gods do not exist, or (2) believe that if they do exist, they don't take care of us, or (3) believe that sacrifices and prayers easily appease the gods. The Athenian thinks that these dangerous people are aided and abetted by confused, foolish, materialistic, atheistic philosophers. What we need in opposition to this whole nasty crowd is substantial evidence that the gods really exist, are far too good to accept bribes, and are not easily appeased. Cleinias and Megillus urge the Athenian to produce this evidence. [Cleinias ...... from Crete Megillus ... from Sparta, doesn't talk much.] In this paper I neglect the second and third task and consider only the first. The Athenian accepts the challenge, and, after a brief prayer for inspiration, begins by pretending that someone has said: "O stranger are all things at rest and nothing in motion, or is the exact opposite of this true, or are some things in motion and others at rest?" To this I shall reply that some things are in motion and others at rest. (893b) What follows is a more or less incomprehensible description of eight different kinds of 'motion' in a fairly broad sense. Here I substitute a list provided (I suppose) by R. G. Bury in the Loeb Classical Library edition of Laws Vol. II, Book X, pp. 328-9 (1) Circular motion round a fixed centre. 2 (2) Locomotion (gliding or rolling) (3) Combination (4) Separation (5) Increase (6) Decrease (7) Becoming (8) Perishing (9) Other-affecting motion (10) Self-and-other-affecting motion The interesting 'motions' are those last two. Expanding them a bit we get: (9') x is able to move other things and be moved by other things, but is not able to move itself. (Think of a passenger car near the middle of a long train. When the train moves forward, the car is pulled by the car in front of it and pulls the car behind it.) (10') x is able to move other things, and able to move itself.1 Presumably it can do this without being moved by anything other than itself. (Think of a horse pulling a wagon.) 1 Thomas Aquinas offers a 'proof' that everything, which is in motion, is moved by something else. (See. Saint Thomas Aquinas, Summa Contra Gentiles Book one: God, translated by Anton C. Pegis. Pp. 86-88.) Anthony Kenny, in The Five Ways, p. 13 says that this 'proof' is borrowed from Aristotle, and Aquinas says the same thing. No doubt they are right. But Aristotle's own view on this matter seems less straightforward. In Physics, Bk. VIII: Ch 3, 254b Aristotle says: "Of things to which the motion is essential some derive their motion from themselves, others from something else." {The basic Works of Aristotle, Richard Mc Keon, p. 363} Kenny himself points out that, according to Aristotle, animals move themselves. (Kenny, p. 14.) On the other hand, Aristotle provides an elaborate discussion of animal movement, which seems to show that in every such case a non-moving part of the animal imparts motion to a moving part. (See Physics, book VIII, Ch 5, McKeon, pp. 372-3.) (Aquinas, of course, believes that the bodies of animals are moved by something other than their bodies, namely their souls.) 3 Athenian: ..... which of these ten motions ought we to prefer as being the mightiest and most efficient? Cleinias: I must say that the motion which is able to move itself is ten thousand times superior to all the others.2 Athenian: Very good; but may I make one or two corrections in what I have been saying? Cleinias: What are they? Athenian: When I spoke of the tenth sort of motion, that was not quite correct. Cleinias: What was the error? Athenian: According to the true order, the tenth was really the first in generation and power; then follows the second, which was strangely enough termed the ninth by us. Cleinias: What do you mean? Athenian: I mean this: when one thing changes another, and that another, of such will there be any primary changing element? How can a thing which is moved by another ever be the beginning of change? Impossible. But when the self-moved changes other, and that again other, and thus thousands upon tens of thousands of bodies are set in motion, must not the beginning of all this motion be the change of the self-moving principle? Cleinias: Very true, and I quite agree. (894c – 895a) Some early worries Isn't there is a missing premise or two? Plato seems to be assuming that there must have been a beginning – the first movement of at least one thing. But why must this have been the case? Couldn't there have been a universe full of activity that had no beginning – that always existed in one form or another?3 Some versions of the 'prime mover' argument include defense of the claim that the universe must have had a beginning.) 2 In the Timaeus Plato says: "...as concerns the motions, the best motion of a body is that caused by itself in itself; for this is most nearly akin to the motions of intelligence and the motion of the Universe. Motion due to the agency of another is less good;" 89 A. Loeb Classical Library, Plato VII. Here it sounds as though the motion of the body was caused by the body. But this, apparently, is not Plato's view. 3 This was Aristotle's view. 4 Where did the initial assemblage of motionless atoms come from? It looks as though it must have always existed or have had a beginning earlier than the first movement. If it had a beginning, what brought that about? The line of argument here is intended as an attack on physicalists like Democritus who, presumably think that in the beginning there was just a big assemblage of motionless stuff. Is the argument meant to be a reductio ad absurdum of this assumption? I don't think this is they way the argument is supposed to go. It looks to me as though Plato really thinks that 'life', 'selfmovement,' 'soul', created the world, or, at least, set it in motion. Athenian: If, as most of these philosophers have the audacity to affirm, all things were at rest in one mass, which of the above-mentioned principles of motion must necessarily be the first to spring up among them?4 Clearly the self-moving; for there could be no change in them arising out of any external cause; the change must first take place in themselves. Then we must say that self-motion being the origin of all motions, and the first which arises among things at rest as well as among things in motion, is the eldest and mightiest principle of change, and that which is changed by another and yet moves other is second. Cleinias: Quite true. (895 a – b) It's a bit difficult to follow the Athenian's line of thought. One is inclined to think that he does not endorse the idea that initially all of the elementary particles were motionless. As it turns out, the Athenian holds that self-movement is "the first origin and moving power of all that is, or has become, or will be.." (896b) Hence, he seems to hold that, in the beginning, all the particles were motionless and then suddenly, in at least one particle, self-movement sprang into being. Given the set up, it is not at all clear why he thinks this must be the way it was. Why should all of the particles have been motionless initially? What suddenly caused there to be a capacity for self-movement in at least one particle, or had that capacity always existed? How long had those particles been sitting there in a 'mass' before the first movement? If for some finite length of time then the first 'movement' was not the voluntary movement of some particle or group of particles. It was the coming into being of the mass. Another (rather stupid sounding) question. When there is self-movement, what gets moved? Here is one possibility: If some physical object, say a magical billiard ball, has the capacity of self-movement, then it can, for instance roll itself, set itself in motion. It is the billiard ball that gets moved. . 5 (It doesn't make much sense to say the capacity itself is moved or moves itself.) Lots of little worries here. But things get worse. Athenian: At this stage of the argument let us put a question. Cleinias: What question? Athenian: If we were to see this power existing in any earthy, watery, or fiery substance simple or compound – how should we describe it? Cleinias: You mean to ask whether we should call such a self-moving power life? Athenian: I do. Cleinias: Certainly we should. Athenian: And when we see soul in anything, must we not do the same – must we not admit that this is life? Cleinias: We must. (895c ) The Athenian is claiming that having a soul is equivalent to having life (being alive) and that having the ability to move itself is equivalent to having life. The conclusion is that having a soul is equivalent to having the ability to move itself. (896a). I take it we now know that some non-living things move themselves. Molecules dart around, or jiggle. Atoms do the same thing. Electrons zip along at incredible speeds. A bold defender of Plato's physics might insist that these little entities are 'alive' have or are little tiny 'souls.' But this is not the accepted view among present day physicists. Presumably, then, we do not identify self-movement with life. Molecules, atoms and electrons are self-movers but, so far as we know, they do not have souls and are not living things. Cleinias: You mean to say that the essence which is defined as the selfmoved is the same with that which has the name 'soul'? Athenian: Yes; and if this is true, do we still maintain that there is anything wanting in the proof that the soul is the first origin and moving power of all that is, or has become, or will be, and their 6 contraries, when she has been clearly shown to be the source of change and motion in all things? (896 a) Thomas Aquinas and Aristotle Aquinas held that Aristotle had proved that everything that is moved is moved by another.5 That is to say, in regard to anything, x, if x is moved then there is a y such that x is not y, and x is moved by y. {Omne quod movetur, ab alio movetur.} He rejects the idea that living creatures can move themselves. (Presumably their souls move their bodies.) If Alice is able to 'move herself' (as we say), must she be something other than that which gets moved? It seems to me that the ability to move itself (or one's self) is not something that can cause movement. (I know this sounds weird.) The ability to draw pictures is not something that can draw pictures, or that can cause pictures to be drawn. The ability enables, or allows, the person to draw. In addition, as I have said, we now know that the ability to move itself is something distinct from life, and from soul. Atoms are self-moving; but they are not alive, and do not have souls. Three ways to go: (1) The 'movement that moves itself' designates soul. It is this that enters the fetus's body at the 'quickening.' It is an entity, not just a capacity or ability. Soul moves the fetus's body. Or: (2) The 'movement that moves itself' is the ability of a living thing, e.g. a frog, to move itself. (It is the frog that produces the frog's movement – e.g. the jump.) Or: (3) There is no such thing as the movement that moves itself. Omne quod movetur, ab alio movetur.) 5 See Saint Thomas Aquinas Summa Contra Gentiles, Book One: God, Translated by Anton C. Pegis, p. 86. 7 Aquinas accepts (3). Plato accepts (1). Back to Plato Athenian: ... what is the definition of that which is named 'soul'? Can we conceive of any other than that which has been already given – the motion which can move itself? Cleinias: You mean to say that the essence which is defined as the selfmoved is the same with that which has the name soul? Atheian: Yes; and if this is true, do we still maintain that there is anything wanting in the proof that the soul is the first origin and moving power of all that is, or has become, or will be, and their contraries, when she has been clearly shown to be the source of change and motion in all things? Cleinias: Certainly not; the soul as being the source of motion has been most satisfactorily shown to be the oldest of all things. (895e – 896b) Here the argument seems to move too rapidly. We began with a mass of particles. (There was no hint that these particles must have been created or arranged by soul.) Then, presumably, at least one particle became able to move itself, dashed off and collided violently with several other particles setting off a cascade of motion. The eventual result was the universe as we see it today. Nothing in this account forces us to hold that there are souls, or that soul, or the motion that moves itself, is the first origin and moving power of all that is. A bit later the Athenian says: .... As soul orders and inhabits all things that move, however moving, must we not say that she orders the heavens? Cleinias: Of course. Athenian: One soul or more? – I will answer for you; at any rate we must not suppose that there are less than two – one the author of good, and the other of evil. Cleinias: Very true. (896de) 8 Like most well educated people in his day, Plato thought that the sun and the moon circle around a stationary spherical earth. At a further distance and at considerable speed, the sphere of the stars revolves. He also believed that all of this motion is 'ordered' by at least two souls, one good and the other bad. Consider the sun. Athenian: Either the soul which moves the sun this way and that, resides within the circular and visible body, like the soul which carries us about every way; or the soul provides herself with a body of fire or air, as some affirm, and from some point without violently propels body by body; or thirdly, she is without such a body, but guides the sun by some extraordinary and wonderful power. [898e -899] In any case, according to Plato, the sun's soul should be regarded as a god (or goddess?). Athenian: And of the stars too, and of the moon, and of the years and months and seasons, must we not say in like manner, that since a soul or souls having every sort of excellence are the causes of all of them, those souls are gods, whether they are living beings and reside in bodies, and in this way order the whole heaven, or whatever be the place and mode of their existence; and will anyone who admits all this tolerate the denial that all things are full of gods? Cleinias: No one, stranger, would be such a madman. [899b-c] Plato offers us a magical little universe; but, unfortunately, the slide from the 'motion that moves itself' to the existence of the gods is illicit and unjustified. Those of us who hold that living things are, in general, capable of moving themselves (in a broad sense of 'moving' that includes growth) are not thereby committed to the view that all living things have souls, nor to any form of polytheism.