The Tripartite Theory of the Soul

Republic IV.439b-441c

  “The matter begins to be difficult, Glaucon, when you ask whether we do all these things with the same thing or whether there are three things and we do one thing with one and one with another—learn with one part of ourselves, feel anger with another, and with yet a third desire the pleasures of nutrition and generation and their kind, or whether it is with the entire soul that we function in each case when we set out for something. That is what is really hard to determine properly.
  I think so too, Socrates" (Republic IV.436a).


1.  Sometimes a person feels thirsty but refuses to drink.
2.  If (1) is true, then the soul has an appetitive part and a reasoning part.
3.  The soul has an appetitive part and a reasoning part.

4.  The motivation in anger can run contrary to those in the appetites.
5.  The motivation in anger is not the motivation in reason.
6.  If (4) and (5) are true, then the soul has a spirited part.
7.  The soul has a spirited part.


1. This premise is a statement of common experience.

"It is obvious that the same thing will never do or suffer opposites in the same respect in relation to the same thing and at the same time. So that if ever we find this happening we shall know that it was not the same thing but a plurality" (Republic IV.436b).

  "Thirst itself is in its nature only for drink itself.
  Hence the soul of the thirsty person, insofar as he is thirsty, is does not wish (βούλεται) anything else but to drink, and it wants this and is impelled toward it (ὀρέγεται καὶ ἐπὶ τοῦτο ὁρμᾷ).
  Clearly" (Republic IV.439b).

  "Are we to say that some men sometimes though thirsty refuse to drink?
  We are indeed, many and often.
  What then, should one affirm about them? Is there something in the soul of those who are thirsty but refuse to drink, something bidding them to drink and something different forbidding them, that overrides (κρατοῦν) the thing that bids them to drink? Doesn't the thing that forbids in come into play, if it comes into play, as a result of calculation, while what drives and drags them to drink is a result of feelings and diseases? Isn't it right for us to claim that they are two, and different from one another? We'll call the part of the soul with which it reasons the λογιστικὸν and that with which it lusts, hungers, thirsts, and feels other appetites, the irrational and appetitive part (ἐπιθυμητικόν), companion of repletions and pleasures" (Republic IV.439c).

   "Does the soul yield to the feelings (πάθεσιν) of the body or oppose them? I mean, when the body is hot and thirsty, does not the soul oppose it and draw it away from drinking, and from eating when it is hungry, and do we not see the soul opposing the body in countless other ways?
   Certainly" (Phaedo 94b).
2. Socrates argues for the truth of premise (2) on the basis of a principle about opposite motions.

He assumes, it seems, that when someone is thirsty, he is moving toward drinking. If he thinks drinking is not in his best interest, he is moving away from drinking. Given the principle about opposite motions, these motions must belong to different things. Since human beings are psychological beings, and thus do whatever they do because of states and processes in their psychology, Socrates concludes that the human psychology has at least two parts.

"Leontius the son of Aglaion, on his way up from the Peiraeus under the outer side of the northern wall, becoming aware of dead bodies that lay at the place of public execution knew a desire to see them and at the same time was disgusted and turned away. For a time he struggled and veiled his head, but finally, overpowered (κρατούμενος) by his desire, he pushed his eyes wide open, rushed up to the corpses, and cried, ‘There, you wretches, take your fill of the fine spectacle!'" (Republic 439e).

   "And don’t we often notice on other occasions that when desires force (βιάζωνταί) someone contrary to his rational calculation, he reproaches himself and feels anger at the thing in him that is doing the forcing; and just as if there were two warring factions, such a person’s spirit becomes the ally of his reason? But spirit partnering the appetites to do what reason has decided should not be done—I do not imagine you would say that you had ever seen that, either in yourself or in anyone else.
   No, by Zeus, I would not" (Republic IV.440a).
In addition to the appetitive reasoning parts, Socrates argues for a third part of the soul: the "spirited" part (θυμοειδές). To establish its existence, he appeals to the case of Leontius. He says that Leontius's anger at himself shows "that the principle of anger sometimes fights against desires as an alien thing against an alien" (Republic 440a). This shows that there is a third part in the soul "provided it shall have been shown to be something different from the reasoning part, as it has been shown to be other than the appetitive" (Republic IV.441a).

5. Glaucon concludes that the motivation in anger is not the same as the motivation in reason because "one can see in children, that they are from their very birth chock-full of rage and high spirit, but as for reason, some of them, to my thinking, never participate in it, and the majority quite late" (Republic 441a). Socrates adds that "one could see in animals that" this is true too (Republic 441b). The argument is that since animals lack reason and reason does not play a controlling role in the actions of children, reason is not responsible for the anger.

6. Given the principle about opposite motions, it follows from (4) and (5) that the soul is tripartite. The third, in addition ore reason and appetite, is spirit.


It is very unclear the arguments are sound.

"[I]n children the first childish sensations are pleasure and pain, and that it is in these first that goodness and badness come to the soul; but as to wisdom and settled true opinions, a man is lucky if they come to him even in old age and; he that is possessed of these blessings, and all that they comprise, is indeed a perfect man. I term education, then, the goodness that first comes to children. When pleasure and love, and pain and hatred, spring up rightly in the souls of those who are unable as yet to grasp a rational account; and when, after grasping the rational account, they consent thereunto that they have been rightly trained in fitting practices:—this consent, viewed as a whole, is goodness, while the part of it that is rightly trained in respect of pleasures and pains, so as to hate what ought to be hated, right from the beginning up to the very end, and to love what ought to be loved, if you were to mark this part off in your definition and call it education, you would be giving it, in my opinion, its right name" (Plato, Laws II.653a). Cf. Laws II.659d.

“Hence the importance, as Plato points out, of having been definitely trained from childhood to like and dislike (χαίρειν τε καὶ λυπεῖσθαι) the proper things" (Aristotle, Nicomachean Ethics II.3.1104b).
What is the desire in reason not to drink?

It is a desire that stems from calculation. The person, it seems, it is aware that he is thirty but decides that drinking is not in his best interest in the circumstances. So the desire seems to be a desire not to relieve one's thirst. Now we need to know what it is to be thirsty.

One possibility is that to be thirsty is to have a desire to drink, but maybe this is too strong.

Maybe being thirsty is being in a certain state of depletion. In reaction to this state, we typically form a desire to drink. This, however, does not always happen.

So now it is not so clear there are opposite motions in the soul because it looks like there is only one desire in the circumstances: the desire of reason not to relieve one's thirst.

What explains why the thirty person does or does not drink?

The answer, it seems, is that the part of the soul in control issues the desire. This is why Plato makes Socrates describe at length the education essential for the organization of human beings he takes to constitute justice in the city. We are born with reason, he thinks, but we need to learn to be rational. We need to mature in such a way that we act for the sake of what reason shows us is best, not for getting the experiences we believe are pleasant.

This still leaves the problem of what it is for one part of the soul to be in control.

It also leaves the problem of what the "biding" is, if it is not a desire, when we are thirsty.

Perseus Digital Library:

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
ὁρμάω, hormaō, verb, "set in motion"
ὁρμή, hormē, noun, "impulse"

"We have a tendency, or at least for a very long time have had a tendency, to understand Plato and Aristotle as if they claimed that it were the task of reason to provide us with the right beliefs or, better still, knowledge and understanding, while the task of the nonrational part of the soul is to provide us with the desires to motivate us to act virtuously in light of the knowledge and understanding provided by reason. But we have already seen that this is not the view of Plato and Aristotle. According to them, it is not the task of reason to provide us only with the appropriate knowledge and understanding; it is also its task to provide us with the appropriate desires. To act virtuously is to act from choice, and to act from choice is to act on a desire of reason. The cognitive and the desiderative or conative aspects of reason are so intimately linked that we may wonder whether in fact we should distinguish, as I did earlier, between the belief of reason that it is a good thing to act in a certain way and the desire of reason which this belief gives rise to, or whether, instead, we should not just say that we are motivated by the belief that it is a good thing to act in this way, recognizing this as a special kind of belief which can motivate us, just as the Stoics think that desires are nothing but a special kind of belief. ... Further, the modern scholarly view, that according to Plato and Aristotle, reason provides the beliefs and the nonrational part of the soul provides the motivating desires, is grossly inadequate in that it overlooks their view that, just as reason has a desiderative aspect, so the nonrational part of the soul and its desires have a cognitive aspect. ... We shall understand this better if we take into account that Plato and Aristotle distinguish three forms of desire, corresponding to the three different parts of the soul, and also, at least sometimes, seem to assume that each of these forms of desire has a natural range of objects which it naturally latches on to. Appetite aims at pleasant things, which give bodily satisfaction; spirit (thymos) aims at honorable things; and reason aims at good things. ... When we see a delicious piece of cake, it will be appetite which has the impression that it would be very pleasant to have this piece of cake. Since appetite lacks reason, it has no critical distance from its impression. For it to have this impression amounts to the same as its having this belief. Similarly, the spirited part (thymos), being sensitive to what is honorable, will have the impression that it would be shameful to have yet another piece of cake" (Michael Frede, A Free Will, 49-51).

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