Plato's Phaedo
Thomas (Janice L.)
Source: Thomas (Janice L.) - Mind and Person in the Philosophy of Religion
Paper - Abstract

Paper StatisticsBooks / Papers Citing this PaperNotes Citing this PaperColour-ConventionsDisclaimer


  1. Essential reading – 13
  2. Further reading – 13
  3. Introduction – 13
  4. Plato's arguments for dualism in the Phaedo – 14
  5. The cyclical argument – 15
  6. The recollection argument – 16
  7. The affinity argument – 17
  8. The argument from opposites – 19
  9. Learning outcomes
  10. Sample examination questions – 20
Full Text
  1. Essential Reading
  2. Further Reading
  3. Introduction
    • The part of reality with which you are most intimately acquainted is yourself. You must use your bodily senses to find out anything at all about the world that lies outside your skin. You must employ your capacity for reasoning and reflection to draw any — even the most simple — conclusions about the rest of reality from the data of sense. But it seems that on any ordinary occasion you need no sensory data and little if any reflection to know about yourself such things as whether you are happy or sad; feeling pleasure, pain, anticipation or guilt; thinking about philosophy or wanting your lunch.
    • But your apparently automatic and unmediated self-knowledge has an obvious class of exceptions. You know that you feel unwell in some way but you need the verdict of a doctor to tell whether you have a bad sprain or a broken bone, whether you are suffering from a persistent cold or tuberculosis. Your body's condition is somehow both your own private state and part of the public world — accessible to others who may be far more expert at diagnosing its condition than you are yourself.
    • You might easily conclude from all this that there are two 'you's: a bodily organism subject to all sorts of physical events and circumstances and an immaterial subject of experiences with a unique access to and knowledge about itself. Sensations, thoughts and feelings are the province of this subjective self. Taking up space in and having a physical effect on the (rest of the) material world is the job of the body.
    • This ‘two-component view of human persons' as Smith and Jones call it has commanded the allegiance of Western philosophers since at least the time of Socrates. The first two chapters of this section will treat in detail the arguments in its support marshalled by Plato (in The Phaedo) and by Descartes (in The Meditations). The third chapter will examine critically arguments which other philosophers and ordinary people have put forward in defence of this view — which has always had, and continues to have, very wide popular appeal.
    • To hold that reality (in particular, each human person) consists of two, utterly different, kinds of substance — material (bodies) and immaterial or mental (minds or souls) — is to subscribe to the metaphysical theory known as dualism. This is a ‘metaphysical' theory because it is a theory about the absolutely fundamental character of everything that exists. It does not deny the evident variety and richness of the world: there are countless, various things and people in the world whose difference one from the next is perfectly real. The dualist is simply persuaded that underneath this rich variety there are only two ultimate categories of thing — mental things and physical things.
    • Typically, substance dualists believe that mind and body have completely different natures but that, different as they are, these two substances can and do interact. Going in one direction, such physical things as activity in your bodily sense organs and physical injury to your body produce such other things as sensations, images of your surroundings and pains in your mind. Going in the other direction, beliefs, desires, feelings and decisions in your mind seem to induce your body to move and to act in one way rather than another.
    • Critics of this so-called 'interactionist substance dualism' question how two substances which are supposed to be of utterly distinct natures could possibly exert any sort of influence on one another. We will return to this objection later in the chapter.
  4. Activities
    • First, look at Smith and Jones 7-8 and Priest 1-8 (and Van Inwagen around 151, although his account is more difficult) for definitions of ‘dualism' and ‘interactionism'. Interactionism is not the only sort of substance dualism. ‘Epiphenomenalism' and ‘parallelism' are also terms for kinds of substance dualism whose meanings you should know. Make notes on the differences as you read.
    • Substance dualism is not the only kind of dualism: at least one other sort of dualism is property dualism. (See O'Hear 211ff, especially 212.)
    • You might also like to make a brief note of what you now regard as the correct view of the relationship between mind and body as you begin studying this subject. Are there two substances of radically different types in you? Are they independent of one another? If they depend on one another, is this a merely temporary dependence (so that they are capable of independent existence)?
    • It is bound to prove interesting to you to see how what you read — and what you think about what you read — change or enlarge your initial views as your work for this subject progresses.
  5. Plato's arguments for dualism in the Phaedo
    • You should begin by reading the Phaedo right through. Like many of Plato's dialogues, this is a fairly approachable work in that it can be read as a little drama - for the story, so to speak. A dialogue is a form which an author can use to make an otherwise somewhat arid philosophical argument or dispute come alive. Just as Descartes uses an informal, autobiographical form which invites the reader to participate in his philosophical excursion, Plato uses the dialogue form to invite the reader to identify with the point of view on mind and body and immortality that he favours. We naturally sympathise and want to side with the brave Socrates who, despite being on the brink of death himself, patiently tries to explain and convince his friends of the indestructibility of the soul.
    • But Plato does not simply rely on literary devices to convince us. He offers four main arguments to prove, or at least rationally persuade us of, the truth of his position.
  6. Activity
    • You should look for these four arguments on your second reading of the text. At this point it will help to use Priest 8-15 as a guide. The four argument titles he employs are helpful labels: since there does not seem to be a completely standard usage among Plato commentators for labelling the arguments, I have adopted Priest's terms:
      … the cyclical argument
      … the recollection argument
      … the affinity argument
      … the argument from opposites.
      (Some commentators suggest that (or at least wonder whether) Plato may have intended the four arguments to be four parts or cumulative stages of one big argument — each stage shoring up dubious parts of the preceding ones. This is an idea to bear in mind and perhaps return to at the end of your work on the Phaedo.)
    • As you look at each argument in turn, first find the part of the text where the argument unfolds. Try to reduce it to premises which together imply a conclusion. Often this is not, straightaway, the conclusion that ‘dualism is correct' or that ‘each human person consists of two substances'. First, Plato argues to a conclusion which, if it is true, then dualism must be true too. His overall aim in the dialogue is to establish the immortality of the soul. Clearly, if the soul is immortal it outlasts its human body: if it were the same substance as the living body it is associated with, the two substances would have the same history and there would be no time when one existed and the other did not. In fact, they would be not two things but one. If the soul is immortal, therefore, and has a longer history than that of the body, then substance dualism is true.
  7. The cyclical argument
    • The general principle or premise of this first argument can be stated as ‘opposites arise out of each other'. Socrates asks Cebes, ‘Does living have an opposite?', to which Cebes replies, ‘Yes, being dead.' So the second premise is ‘living (or being alive) and being dead are opposites.' From these two premises Socrates draws the conclusion that living comes to be out of that which is dead just as being dead comes to be out of that which is living. He takes this conclusion as evidence that there is reincarnation1 — a cyclical process in which life emerges from death and death is not the final end of anything.
    • Should we accept the principle that opposites arise out of each other? First it must be said that it is not clear what is being claimed here. It is unarguable that any beginning of existence (say the birth of a baby or the making of a piece of pottery) can be described as a coming to be of something out of its opposite. The individual sperm and egg, the nutrients taken from its mother which nourished the growing foetus2 - none of these was itself a baby although it seems a bit odd to describe each of these things as ‘a non-baby' or ‘the opposite of a baby'. Similar things could be said of the clay3 from which the pot was made — the clay is not naturally thought of as ‘a non-pot'. The sperm and egg, the clay4, seem to be simply ingredients in what comes into being. On the other hand, it seems less than obvious that death is an ingredient in the creation of life or that life is an ingredient in death.
    • Priest finds two further weaknesses in the cyclical argument. Even if we accept the general principle that opposites arise out of each other, it seems open to question to say that death itself is a kind or mode of existence. Surely death is, rather, the end of being (and dying is a transition from being to not being at all). If Socrates is portrayed as assuming otherwise, then he would seem to be committing the mistake philosophers call ‘begging the question'.
    • Begging the question' means ‘assuming what you set out to prove'. Described thus baldly, it sounds like an error which only a fool or a scoundrel would make, but of course it is sometimes difficult to be sure about the buried assumptions underlying what we assert. In this case, it looks as if Socrates is in danger of assuming that being dead (i.e. being disembodied)5 is a mode or way of being for souls — which was what he set out to prove. However, it is clear that the cyclical argument is not meant to stand on its own as a proof — the subsequent arguments are meant to supply any deficiencies in the first.
    • Before going on to the recollection argument, notice Priest's other criticism of the cyclical argument. Priest asks why we should accept ‘being dead' as the relevant opposite of ‘alive'. Would it not be equally or even more correct to regard ‘inanimate' or ‘not alive' as the opposite of ‘alive'? Then a living person would be something which has come to be out of ultimately inanimate or non-living matter (such as the food that nourished the baby's mother) and will, in eventually dying, return to its inanimate ingredients. Further argument is wanting to establish that a person who has ceased to be alive continues to exist as an immortal soul rather than as inanimate constituents.
  8. The recollection argument
    • The recollection argument is designed to show that our souls existed before we were born. If this were true, dualism would also be true: if the soul predates the body, soul and body have distinct histories and are clearly not the same thing. How could one establish that the soul or mind existed before the bodily organism came into being? Plato's strategy is to show that a living person has knowledge he has not acquired since birth. If you know something in the present, you must have acquired that knowledge at some time in the past. If you did not learn it at any time since you were born, then you must have learned it before you were born. Plato is not suggesting that knowledge is acquired in the womb. Rather he is going to claim that (in fact, all) knowledge is acquired by the soul before it is united with its body.
    • Plato's view of knowledge and its acquisition is certainly unusual. On his view, to have something worthy of the name of knowledge on any matter is to have contact with something perfect and abstract. Only an otherworldly entity like an immaterial soul can be the right sort of subject of such experience. Only otherworldly, eternal, perfect and unchanging objects (which Plato calls ‘the Forms' or ‘Ideas' — for example, ‘justice itself' or ‘beauty itself') can form the subject matter of such an encounter.
    • And of course we do, in this life, have knowledge — we do, to take a crucial example, understand and know the meanings of certain words of our language (e.g. ‘beautiful' or ‘just'). Now these meanings, on Plato's view, are in fact whatever objects are denoted or picked out by those words (e.g. the beautiful itself or the just itself). But those objects cannot be objects of ordinary worldly experience because they just are, invariantly, whatever they are (beautiful or just or whatever it may be). In contrast, any object of worldly experience may be beautiful (just) from this point of view or to this person but not beautiful (just) from that point of view or to that person.
    • So the most that earthly experiences of worldly objects can do is trigger memories (recollections) of the Forms, but that is all the ‘teaching' that experience can do. Our real learning of the objects that give meanings to our words must have been a (prenatal) encounter with the otherworldly objects (the Forms) themselves.
    • In the Meno (another dialogue of Plato's) there is a famous scene in which Socrates elicits the answers to questions about the properties of certain geometrical figures from an unschooled slave boy who has clearly never been taught geometry. If the slave boy knew the answers (as he did) despite never being taught anything of the matter in this life then, Socrates maintains, he must have acquired the knowledge before his incarnation. His soul must pre-date his body. This doctrine from the Meno is appealed to again in the Phaedo, forming the basis of the Recollection Argument for the immortality of the soul.
    • Socrates' friends, Simmias and Cebes, grant that this argument may prove the prenatal existence of the soul but object that it does not prove the soul's post-mortem existence. The Socratic answer to this objection is that the cyclical argument and the recollection argument need to be taken together and that together they indicate that there is a ‘perpetual reciprocity in coming to be' which strongly supports belief in immortality. Since, at the moment, we are looking at these arguments in the Phaedo only with a view to discovering how strong a defence they give to substance dualism (rather than the further claim that the immaterial part of the duo is immortal), we need to ask whether Socrates' friends are right in what they grant. Does the recollection argument prove the pre-natal existence of the soul?
    • It must be conceded that the account of knowledge upon which the Recollection Argument so heavily depends is fraught with difficulties.
      1. First, the existence of perfect Forms (as the content of knowledge) is highly controversial.
      2. Second, the claim that knowledge is nothing but acquaintance with and recollection of immaterial Forms is, again, something that needs a strong argument in its defence.
      3. Third, the sceptical view that we cannot gain any knowledge from experience (say, by using our senses) goes against common sense so powerfully that it would need an equally powerful philosophical argument to win our acceptance of it.
      4. But in the present context, the gravest and most pertinent objection is that (fourth) the whole account of recollection relies on our accepting that there is a realm of the Forms, a part of reality which is abstract, immaterial, eternal and unchanging.
    • To make this last assumption is to beg the question in favour of dualism once again. It is to assume that reality consists of two sorts of thing, material bodies and immaterial, abstract objects. From this assumption it is a very short step to the view that any human person consists of one substance belonging to the material part of reality and a second substance belonging by nature to the immaterial realm. Again, we have a persuasive picture rather than the sort of successful argument that we would welcome; one which would carry us from premises whose truth is already established to an independent conclusion not already assumed in the premises.
  9. The affinity argument
    • The first premise of this argument is that while composite things (things made of parts) are liable to destruction, non-composite things are not liable to destruction.
    • The second premise is that the soul or mind is non-composite — it has no parts. Socrates says that the soul has affinity with or is similar to the non-composite, never-changing Forms (e.g. being itself, the beautiful itself, the equal itself). The soul is like the Forms (akin to the Forms) also in being invisible.
    • The conclusion must be that the soul, like the Forms, is indestructible. It will last for ever. And since it will last for ever although the body, being composite, will die and decay, the two things, having different properties and different histories, are genuinely two substances.
    • As Priest points out (12), this argument (despite appearing to derive its conclusion by deductive reasoning from its premises) is once again vulnerable to the criticism that it begs the question. Another way to express this criticism is to say that the argument moves in a vicious circle. We must assume dualism before we can make sense of the soul's having properties (e.g. non-compositeness) the body lacks. All Plato is entitled to, until substance dualism is an established fact, is the weaker claim that people have both mental and physical aspects.
    • Activity: Do you think that this weaker view (which is strongly supported by common observation) is enough to get some version of the affinity argument started? Write down your view.
    • The really important objection is Priest's second point. It looks as if Socrates has not done anything to establish that soul and body are such that they cannot share the properties which are crucial to the characterisation of each. ‘A person has both mental and physical aspects' seems a truth of common sense. Why shouldn't we conclude that one kind of substance, one single substance, is capable of having both mental and physical properties?
    • Simmias and Cebes each have an objection to the affinity argument. Each objection involves an analogy:
  10. Simmias objection
    • Simmias compares what Socrates says about the soul with what could be said about the tuning of a musical instrument such as a lyre. The tuning of a lyre is something invisible and non-physical while the lyre itself is physical and destructible. But we do not conclude that the lyre's tuning will outlast the lyre. Similarly, we have no warrant to go from ‘the soul is invisible and non-physical' to ‘the soul will outlast its body'.
    • Socrates has three replies to this. Each reply consists in pointing out a disanalogy, a way in which the comparison Simmias has made fails to be an exact comparison:
    • 1. The lyre's tuning does not pre-date the lyre's existence. If it could, then we would have to ask seriously whether the tuning could not also outlast the instrument and we might feel that the answer should be ‘yes, it could'. But of course we feel that an instrument's being in tune depends (at least) for its existence on the continued existence of the instrument. In Lewis Carroll's book, Alice in Wonderland, there was a Cheshire Cat who left his smile behind sometimes: this is entertaining nonsense in a children's story precisely because, as we all know, a thing like a smile or the tuning of a lyre cannot exist independently of the smiling face or the well-tuned instrument.
    • 2. Socrates' second reply is that the lyre and its tuning differ in another way from the body and its soul. In the lyre's case, the physical parts of the lyre have an effect on the tuning but the tuning does not in turn have any effect on the lyre. In the body's case, there is a two way causal connection. The soul affects the body (say, when a decision you make leads to your body's acting to carry out that decision). The body also affects the soul or mind (say, in sense perception when light entering your eyes leads your mind to have a visual experience of what lies in front of your eyes).
    • 3. The third disanalogy Socrates finds between having a soul and being in tune is that being in tune can be a matter of degree — an instrument can be more or less in tune — whereas possession of a soul or mind is an all-or-nothing thing.
    • Activity: Consider whether Simmias should give up his analogy or should be led by it to give up substance dualism. Make notes on your view.
  11. The argument from opposites: Cebes' objection to the affinity argument
    • The analogy which Cebes uses to criticise the affinity argument is as follows. Even if it were a fact that the soul outlasts the body, this fact would not be enough to prove that the soul is immortal. After all, a man's cloak may outlast him but we do not argue from this to the immortality of cloaks.
    • The argument from opposites is Socrates' reply to Cebes' objection.
      1. The first premise is (as Priest puts it — 15) that it is impossible for something to possess and to lack a certain property in exactly the same respect.
      2. The second premise is that the soul has life as a property in the same way that an odd number has its ‘oddness', as part of its very essence.
      3. Therefore, the soul could not possibly have anything to do with death any more than an odd number could become even.
    • So Cebes' analogy between a dead man and his soul on the one hand and, on the other hand, a dead man and his cloak fails: it is not an exactly parallel case. A cloak and a human body are both clearly material things so that their natures or properties are not true opposites. In contrast, the soul and the body are of opposite natures and properties. A soul is alive of its very nature and this, not its outlasting of its body, is what accounts for the fact that it cannot cease to be.
    • Activity: Look again at each of the four arguments. Are any of them free from unwarranted assumptions? Do any of the arguments avoid assuming what they were meant to prove or establish? Make notes on the arguments and your own conclusions about them.
  12. Learning outcomes
    • When you have finished working through the material in this chapter and the recommended reading you should be able to:
      …Outline the four arguments for substance dualism in Plato's Phaedo.
      …Examine them critically.
      …Assess their success.
    • It is unlikely that these arguments would carry conviction with anyone who was not already strongly inclined towards dualism since they all, in various ways, assume the substance dualism they need to prove if Plato is to succeed in the dialogue's primary aim of establishing the immortality of the soul.
  13. Sample examination questions
    • Outline and assess critically Plato's arguments for mind—body dualism in the Phaedo.
    • Discuss the arguments of any one philosopher for the view that the mind is a non-material substance. (This question could also be answered using Descartes' arguments to be examined in Chapter 2.)


Part 1 (The Metaphysics of Mind and Body); Section 1 (Dualism); Chapter 1. Hard Copy filed in "Various - Papers on Religion Boxes (Heythrop)".

Text Colour Conventions (see disclaimer)

  1. Blue: Text by me; © Theo Todman, 2020
  2. Mauve: Text by correspondent(s) or other author(s); © the author(s)

© Theo Todman, June 2007 - Sept 2020. Please address any comments on this page to File output:
Website Maintenance Dashboard
Return to Top of this Page Return to Theo Todman's Philosophy Page Return to Theo Todman's Home Page