The following is another essay I wrote back in 2008.
Does Plato Provide A Good Argument For the Immortality of the Soul?
Plato (423 – 347 BC) provides several arguments for his claim that the soul is immortal, and for various reasons none of these are convincing. Their fundamental flaw is that the existence of a kind of soul to which the arguments apply is presupposed. Most of the arguments are found in his Socratic dialogue Phaedo (of which the Recollection Argument is also found in the Meno, but I do not cover that version here) and a further important one is found in the last book of The Republic (another Socratic dialogue).
I will evaluate each argument in order, but first it will be useful to make some clarifications. By immortality we mean that the soul, an immaterial entity distinct from the body, will survive separation from the body at death and is indestructible. But what does Plato mean by soul? In many contexts the Greek word is closer to our notion of ‘life’ than ‘soul’; it effectively denotes mental phenomena.
There are four arguments for the immortality of the soul in the Phaedo, namely the Cyclical Argument, the Recollection Argument, the Affinity Argument, then after a a period of reflection on the previous two arguments, the Final Argument. The Cyclical Argument takes the following form: All things come to be from their opposite and because the opposite of life is death, life must therefore come from death. Plato says this must be the case or else everything would end up dead. Thus, the souls of the dead must exist prior to their reincarnation. One criticism of this argument is that death is contrary to life, but it is not its contradictory opposite; whilst it is impossible for something to be both dead and alive it is possible for something to be neither dead nor alive, e.g. a stone. If life arises out of such non-life rather than death, a pre-existent soul is not needed and life will eventually revert to non-life (a specific kind of non-life called death). The assumption Plato makes that if life did not come from death everything would end up dead is a strange one, because this conflicts with his own views about philosophical wisdom disrupting the cycle of life and death, should not everyone end up a philosopher?
The Recollection Argument runs as follows: we have knowledge that we have not been taught (e.g. we can come to knowledge of mathematical truths through the use of our reason alone), because we have never learnt this we must have known it before we were born and therefore the soul must have pre-existed our birth. This argument has several problems, firstly it would only demonstrate the prior existence of the reasoning part of the soul, not of its desires and emotions which are important to Plato’s conception of the afterlife.
The argument also confuses a priori knowledge with the innate knowledge (knowledge we were born with). The belief in innate knowledge was successfully critiqued by John Locke in the 17th Century. Locke’s attack on the doctrine was two-pronged: firstly, the traditional backing of ‘universal assent’ given to the theory does not exist and if it did it would not be sufficient to prove innateness, but only universal favour. Secondly, there are a great many people who are ignorant of the propositions purported to be innate, and some will go their whole life without ever thinking about these topics. If people truly knew them innately then surely they would be aware of them from birth, and they would not need to be awakened by the use of reason. A priori knowledge only appears to be innate because itis gained independent of empirical evidence, and because of this it makes no reference to the time at which it was acquired, thus accounting for the mistaken conclusion that we are born with it.
The Affinity Argument is more subtle, it says that the soul, by contrast to the body, is invisible, immaterial and indivisible and because of this, Plato reasons, it is likely to be indissoluble and deathless. Crucially, the reasoning part of the soul is applicable to this argument because it resembles the forms and the gods, on the grounds that it is rational and has the natural tendency to rule. But because this argument works on the basis of an analogy and is thus an inductive rather than a deductive inference, it would not have been seen as reliable within Plato’s epistemological system.
In the period of reflection the interlocutor Simmias lays his materialist objection against the Affinity Argument: that the soul’s relation to the body resembles more a harmony played on an instrument than it does an instrument of ruling the body, and that when the strings of the instrument are broken, the harmony ceases to be. No flaws in the Cyclical Argument are elaborated in the dialogue, and because it isn’t again mentioned we can reasonably infer that it is deemed unsuccessful. It is raised that the Recollection Argument has an insufficient conclusion, only proving –at best– the prior existence of the soul rather than its immortality (an objection that applies equally to the Cyclical Argument) and there is no reason why this cycle must continue forever and not end at the destruction of the soul at some point.
The Final Argument in Phaedo says that the soul can satisfactorily be called the cause of life, itself participating in the form of life, and therefore cannot admit death. This does not follow, because although the soul may be the source of life and cannot therefore exist and be dead, it may cease to exist. Further, part of Plato’s definition of cause is that it be both necessary and sufficient for all of its effects which is problematic because it would follow that everything that is alive i.e. plants as well as humans, must have rational souls, which is implausible and does not cohere with the rest of his theory.
We now move on to the argument for immortality from Book X of TheRepublic. The first premise is: that which can destroy each thing, if anything can, is the bad associated with it. Bad things associated with the soul include: ignorance, injustice, licentiousness, and cowardice, which collectively come under the term ‘vice’. Vice is the specific bad thing associated with the soul, but because it never directly results in the death of a particular soul, the soul must be immortal. Somewhat hesitantly, this is regarded as a valid argument, and because it has the right conclusion (that the soul is immortal) it is more plausible than any of the arguments from Phaedo. We do, however, have good reason to think that it contains at least one false premise and some presupposition, such that the argument is certainly not sound.
Firstly, there seems to be an awkward presupposition, namely that everything has only one bad thing, especially when we are told that vice is the specific bad thing associated with the soul. Why should this be? Wood provides us with a counter-example, because it can be destroyed by both rot and fire. The argument also assumes that something cannot be destroyed by something connected with it being destroyed (i.e. the soul via its connection, dependence on the body). Alternatively, the soul might be destroyed by the evil of the body, which could plausibly cohere with the antipathy towards the body in Plato’s system. The fatal flaw, however, is one that affects the Phaedo arguments also: that the premises are false or at least inadequate because they presuppose that there exists a spiritual soul. Unless this can be proved there is no reason why that which Plato calls the soul should not be identical in some way with the body and therefore susceptible to destruction along with it, and Plato nowhere even attempts to prove the existence of the soul as he conceives of it.
So what is the ‘soul’ really like? A popular contemporary theory is that of Richard Dawkins. His physicalist theory is based on genetics and sees the person, including the mind, as a construct based on replicating genetic information. Dawkins’ theory also supports a form of immortality: genes together with memory-based replicators of non-genetic information (e.g. science and culture) which he calls ‘memes’ allow post-mortem survival through children and the continued importance of our work and creations. But perhaps there is potential for immortality within a theory closer to that of Plato.
Metaphysical monists such as the Ancient Greek Eleatic school argued for immortality owing to our indestructible reality during the period of time at which we do exist, which when viewed from the perspective of eternity means that we always exist. These thoughts were more clearly exemplified in the views of the 17th century philosopher Spinoza and by Einstein in defence of the B-Theory [Tenseless Theory] of time. Of course it follows that if no point in time is any more real than any other, everything that exists at each point in time will remain in existence there. Although Plato was not a monist he could have made use of similar ideas.
While Plato was probably sincere in his arguments, he would have realised that if they had failed, his theory of the forms would necessitate a kind of immortality. This is that “the soul… shares in the eternal being of the forms. … [W]e can regard the most important part of ourselves as indestructible… because it has no content save the eternal objects that it contemplates. By identifying myself with eternal truths I know myself, that self at least, is immortal.” This notion retains at least some plausibility for anyone who subscribes to Realism about universals.
Overall, although the Republic Argument is the strongest due to its validity and correct conclusion, it is not at all plausible. Superficially, it appears contrived and it is ultimately insufficient, as are all of the arguments, because of the presupposed existence of the soul. The Republic Argument is certainly the most plausible argument when we believe in the soul, and as such it would have been apt to hold the most weight in the West until the existence of an immaterial soul began to be questioned on a wide scale. All the other arguments are weaker still: whilst the Affinity Argument is perhaps the most plausible superficially, because of its straightforwardness, it is far from conclusive. The Cyclical and Recollection arguments, although stronger, are fundamentally flawed due their irrelevant conclusions. The Final Argument in Phaedo, despite convincing Socrates’ interlocutors, is invalid. In conclusion, none of Plato’s arguments are good enough to prove the immortality of the soul, but whilst it seems that his conception of the soul was deeply flawed, it is at least considerably more plausible that there is a sense in which something important of us is immortal.
Annas, Julia, (1981), An Introduction To Plato’s Republic, 1st Edition, Oxford, Oxford University Press
Bostock, David, (1999), ‘The Soul and Immortality In Plato’s Phaedo’, In Fine, Gail (ed.), Oxford Readings In Philosophy: Plato Vol. II, Oxford, Oxford University Press
Clarke, S. R. L, (1994), ‘Ancient Philosophy’, In Kenny, Anthony (ed.), The Oxford Illustrated History of Western Philosophy, New York, Oxford University Press
Dawkins, Richard, , (1989), The Selfish Gene, 2nd Edition, Oxford, Oxford University Press
Locke, John, , An Essay Concerning Human Understanding, Nidditch, P. H. (ed.), (1975), Oxford, Clarendon
Plato, Phaedo, Grube, G. M. A. (trans.), (1981), Five Dialogues, Indianapolis, Hackett Publishing Company Inc.
Plato, The Republic, Lee, Desmond (trans.), , (2003), 2nd Edition, St. Ives, Penguin Group
 Annas, (1981), p.123
 Plato, Phaedo, 69e-72d; on reincarnation see the excellent short story, ‘The Egg‘
 Bostock, (1999), p. 422
 Plato, Phaedo, 72e-77d
 Bostock, (1999), p. 422
 Locke, , pp. 48-50
 Plato, Phaedo, 78b-80b
 Bostock, (1999), p. 422
 Bostock, (1999), p. 422
 Plato, Phaedo, 84c-95e
 Plato, Phaedo, 85e-86d
 Plato, Phaedo, 87a
 Plato, Phaedo, 88a
 Plato’s theory of the forms is elaborated in books VI and VII of The Republic
 Plato, Phaedo, 95e-106e
 Bostock, (1999), p. 424
 Plato, The Republic, 608d-611a
 Dawkins, , pp. 189-201 – For more on this theory see also his books: The Extended Phenotype and River Out of Eden
 Levine, (2008), p.17
 Clarke, (1994), p.27
 In the last year I’ve read a great but rather populist defence of the soul, More Than Matter by Keith Ward.