The key concept is μέθεξις methexis, participation or sharing in the Forms:

Things exist by virtue of their participating in their distinctive being or Form (Phaedo 101c).

The soul being that which imparts life to the body (105c), it necessarily participates in the Form of Life.

The soul necessarily participating in the Form of Life, it is necessarily deathless.

Being necessarily deathless, the soul cannot die, it must retreat or be destroyed.

Being necessarily deathless and therefore indestructible, the soul cannot be destroyed, it can only retreat.

Ergo, the soul retreats away from the body and to the other world (Hades).

This is the inescapable conclusion.

Do we need to crib on an issue so fundamental to understanding Plato? Dialectic is (friendly) wrestling with each others' convictions. Those convictions may never really change, but the terms of the competition do. And that change in terms is a growth in the ability of both interlocutors to confront his or her own convictions. It is a community in contrariety that is the engine of language, though contradiction (the binary division of being) may yet be the mechanism of reason. That mechanism is epochal, but the personal dynamic of that community is not contiguous to or within any epochal structure. It is not immortality, but it is a personal impact on all time regardless of where we are in the flow of it. Dialectic is meant to involve us in taking personal responsibility for our convictions, and for the terms of our expressing them, not in building an edifice of laws by which we can abdicate it. Plato and Socrates were humanists.

But a lyre does need to be tuned. — Metaphysician Undercover

Right, but a lyre is not a living thing. It is not capable of self-movement or self-attunement.

Wayfarer makes an important point:

But the harmonies, which are ratios, don't come into existence when the lyre is tuned. They are the same whether there is any lyre or not. — Wayfarer

With all his talk of opposite forms Socrates neglects to consider Harmonious /Unharmonious or

'Tuned and Untuned'. The tuning of a lyre exists apart from any particular lyre. It is the same relationship between the Equal and things that are equal, and the Beautiful or Just and things that are beautiful or just.

The Tuning of the Lyre exists apart from any particular lyre. The Tuning is the relationship between frequencies of the strings. It is this relationship of frequencies that is used to tune a particular lyre. Analogously, the Tuning of the body exists apart from any particular body, it is the relationship of bodily parts. (edited) — Fooloso4

The question is why Socrates neglected this argument? First, they had already agreed that:

“… our soul is somewhere else earlier, before she is bound within the body.” (92a)

but that does not mean that in evaluating the argument that we too must accept it. As was correctly pointed out:

Dialectic is (friendly) wrestling with each others' convictions — Gary M Washburn

The reader of a Platonic dialogue should not be a passive observer simply accepting what has been said.

Second, the argument that the soul is a harmony means that the fate of a particular soul is tied to the fate of a particular body.

All of the arguments have the same problem. The distinction between Soul itself, that is, the Form Soul and the individual soul means that even if Socrates is able to show that Soul continues to exist after death, he has not shown that the individual soul does.

I think dialectic is a strange and elusive thing that can mean different things to different people. Sometimes it may be difficult to agree on a definition of it, let alone on the terms on which it is to be conducted. Participants may or may not play a straight bat, etc.

What ought to be certain, though, is that as a minimum requirement when considering the dialogues two rules should be observed, viz. (1) to keep as close to the original text as possible (and in this case it is possible if there is a will to do so) and not insert things that are not there, and (2) to read Plato within his own framework.

For example, if we say, “Yes, the immortality of the soul has been proved and accepted as fact in the dialogue but we don’t need to accept that,” then we abandon Plato’s work and construct our own. In which case we might as well write a dialogue from scratch and not concern ourselves with Plato.
So, I think it all depends on what the "dialectic" is supposed to achieve. Are we discussing what a dialogue is saying, or what we would like it to say?

Too broad a view and we are using Plato as a scene of personal exposition? Too close and we're cherry-picking?

Here's a cherry: at the end of Lysis, does Socrates say "..., we still don't know what friendship is?" or "..., we still don't know which one the friend is?" Your answer will determine what kind of Platonist you are.

The question of who the friend is cannot be answered apart from the question of what friendship is. But what is at issue in practical not theoretical, the goal is not to find the definition of friendship but the ability to identify a friend in distinction from someone we may call a friend.

David Bolotin gives an alternative "perhaps more literal" translation of the closing words in the footnotes to his translation:

"we have not yet become able to discover" . This final phrase may also be translated as follows: but we have not yet been able to discover that he who is a friend is [i.e., exists]" (Plato's Dialogue on Friendship)

The dialogue ends in aporia. It is up to us to determine who, if anyone, is our friend.

Have you determined that I am any kind of Platonist?

Determining "what kind of Platonist you are" seems to be part of the problem.

According to some, Socrates had his own "philosophy" that is to be carefully distinguished from that of Plato who, apparently, somehow "distorted" Socrates' teachings and whose own teachings were in turn "distorted" by later Platonists, etc.

At the same time, we cannot know for certain what Socrates taught aside from the patent fact that he asked questions and that, apparently, "he knew that he knew nothing" - which, admittedly, isn't much help.

Even the question as to whether Plato himself was a Platonist has been raised in some quarters.

This being so, it seems advisable to read the dialogues not as "Platonists" or "anti-Platonists" but as impartial and objective observers after which, each reader can draw out his own conclusions or construct his own dialogue as the case may be. And at that point, the dialectic ends and monologue takes over ....

It is worth noting that the dialogue is named after a person, Lysis, rather than the topic, friendship. In short, what is at issue here as in other dialogues is the question of self and other selves.

This ties in nicely with the question of the self in the Phaedo, specifically with the problem of the self as a whole and the analysis of the self as divided or doubled, that is, the place or topos of self in relationship to the separation of body and soul.

The soul is that which imparts life to the body in the first place (105c - d). Without the soul there would be no body. — Apollodorus

This is why the immaterial soul is prior to the material body.

Right, but a lyre is not a living thing. It is not capable of self-movement or self-attunement.

Wayfarer makes an important point: — Fooloso4

Wayfarer's point explains why we must conclude that the immaterial soul is prior to the material body.

And when we proceed further down this route, we see that to account for the real order which inheres within inanimate things, we need to assume an immaterial existence (God) , as prior to the material things of the world.

With all his talk of opposite forms Socrates neglects to consider Harmonious /Unharmonious or — Fooloso4

I don't think Socrates neglects this at all. In fact, it is focused on in many dialogues. When the mind succumbs to the desires of the body, and is overwhelmed by these desires, to the point of irrationality, then the mind no longer rules, and the person gets into an unharmonious, or disordered state.

The question is why Socrates neglected this argument? — Fooloso4

I don't see that you have a point. As I already pointed out to you, what is referred to by "the tuning of a lyre" does not exist independently of a particular lyre. The tuning of a lyre is always carried out, and must be carried out on a particular lyre. What is independent of the particular lyre is the principles by which a lyre is tuned, or as I said earlier "how to tune a lyre".

Second, the argument that the soul is a harmony means that the fate of a particular soul is tied to the fate of a particular body. — Fooloso4

But Socrates demonstrates, by the argument we've been discussing, that this idea, "that the soul is a harmony" is false.

The soul participates in the body as much as any object participates in itself. Something without parts can't subsist on it's own. The world is what is real. Plato brought up interesting ideas for his time but he is quite cooky. If dualism is true, maybe the soul vanishes when the body dies. There is obviously an unbreakable connection between body and soul. Only the resurrection of the body can insure immortal existence

This is why the immaterial soul is prior to the material body. — Metaphysician Undercover

This is made crystal clear by the text and ought to be beyond dispute.

Unfortunately, Fooloso4 has a long history of making claims for which either (1) he presents no evidence or (2) which are positively contradicted by the evidence. Which is not surprising as he is a self-declared follower of Leo Strauss whose musings about Plato are pseudo-scientific gobbledygook.

When pressed, he offers two kinds of answer, either (1) that the evidence is there but only “careful” readers like himself can see it or (2) that the issue “has already been discussed or addressed” and there is nothing further to say.

I think we have seen where his theories lead to. He fails to understand that to say (a) “the sirens sing or chant to Odysseus in order to charm, spellbind or put a spell on him” as in Xenophon (Mem. 2.6.11), is totally different from saying (b) “the mother sings or chants to her child in order to soothe it” or, as in the Phaedo, “one must sing or chant to oneself in order to soothe or comfort oneself (with knowledge of the immortality of soul and afterlife).”

The same applies to statements like "the argument that the soul is a harmony means that the fate of a particular soul is tied to the fate of a particular body."

Among other things, this totally ignores the fact that the soul is "tied to the fate of a particular body" only so long as the soul inhabits the body, after which it returns to the world of the Forms with which the soul has much more in common than with physical bodies.

The dialogue clearly states, and scholars have long acknowledged, that the soul here is a special case for the simple reason that it is a life-imparting thing that necessarily participates in the Form of Life (cf. 79b) and that therefore any analogy with snow or anything else apart from soul itself is necessarily an imperfect analogy.

But, of course, when people latch on to irrelevant or imagined details to which they accord disproportionate importance, then we enter the realm of never-ending labyrinths from where there is no easy way out ... :smile:

Wayfarer's point explains why we must conclude that the immaterial soul is prior to the material body. — Metaphysician Undercover

His argument is that Harmony is a universal. What is at issue is the difference between the universal and particular. Harmony itself is prior to any particular thing that is in harmony.

I don't think Socrates neglects this at all. In fact, it is focused on in many dialogues. — Metaphysician Undercover

Elsewhere he accepts that there is a harmony of the soul, that the soul can either be in harmony or out of harmony, but here he rejects it. We need to take a step or two back to see what is going on.

Prior to Socrates examination of the idea that the soul is a tuning Socrates says:

“ For I am calculating - behold how self-servingly!- that if what I’m saying happens to be true, I’m well off believing it; and if there’s nothing at all for one who’s met his end, well then, I’ll make myself so much less unpleasant with lamenting to those who are present during this time, the time before my death.” (91b)

The truth of the matter has not been established. Socrates points to the fact that it may still be that in death there is nothing at all, it is the end.

The argument proceeds on the assumption that:

… our soul is somewhere else earlier, before she is bound within the body.” (92a)

Socrates argues that the soul cannot be an attunement if the tuning existed prior to what is tuned. But it is only an assumption that the soul exists prior to the body. The alternative, that the soul is not some separate immaterial thing, undercuts the argument that the soul cannot be an attunement of the body.

When the mind succumbs to the desires of the body, and is overwhelmed by these desires ... — Metaphysician Undercover

In the tripartite soul of the Republic, desire is located in the soul.

This assumption, that the soul exists prior to the body, is based on a more fundamental assumption, that body and soul are two different things. That assumption needs to be examined.

But Socrates demonstrates, by the argument we've been discussing, that this idea, "that the soul is a harmony" is false. — Metaphysician Undercover

But as you pointed out, elsewhere he says that it is a harmony.

Without certitude which one is which, an issue which "philosophy" perversely ignores, the whole edifice of inference by dividing reality between premise and negation is vapid. The answer to the question which one is the friend is not this one, or not me. That is, neither one nor the other is the friendship. That is, the fundamental dynamic of reason may well be decisions either/or (quantification), but the fundamental dynamic of meaning (worth, or the good--the qualifier) is neither/nor. That decision is the most decisive of all, and the portal to understanding agency, and how personal character trumps all the laws of impersonal mechanics. Death is the ultimate and most completed act of being, for it means loss so complete the perfect individuality of that loss is painfully recognized the most completed term of being, and the only engine of the terms of discovering who we are. But there is no one that engine of recognition of person and the good is. It is too complete, and too itself, to be so quantified. The dialectic is the intimation of the worth of time. That is why Socrates puts the good above being and number.

"Death is the most complete act of being". That could have be written by Sartre himself

I'll take that as a compliment.

It was meant thusly. Sartre writes of being and nothing spread like ripples to compose the universe. The Ideas of Plato are in the world and in us. They are transcendental. There is nothing transcendent

But Socrates demonstrates, by the argument we've been discussing, that this idea, "that the soul is a harmony" is false. — Metaphysician Undercover

Correct. Simmias himself acknowledges that his theory, though "held by many", has not been demonstrated and he discards it in favor of recollection and immortality:

“Well,” said he, “there is no harmony between the two theories. Now which do you prefer, that knowledge is recollection or that the soul is a harmony?”

“The former, decidedly, Socrates,” he replied. “For this other came to me without demonstration; it merely seemed probable and attractive, which is the reason why many men hold it. I am conscious that those arguments which base their demonstrations on mere probability are deceptive, and if we are not on our guard against them they deceive us greatly, in geometry and in all other things. But the theory of recollection and knowledge has been established by a sound course of argument. For we agreed that our soul before it entered into the body existed just as the very essence which is called the absolute exists (92c – d).

Plus, as already stated, the soul being a special case, no comparison is perfect. And, when making comparisons, we must consider not only similarities but differences:

When making comparisons it is useful to see not only similarities but differences. Socratic philosophy proceeds by rational inquiry, by the critical examination of opinion, that is, dialectic. — Fooloso4

And it should be obvious to everyone that there are more differences than similarities between the soul and the harmony of a musical instrument.

The dialectic is the intimation of the worth of time. — Gary M Washburn

The worth of time is highly important in more than one sense. In Ancient Greek tradition, the souls of the departed go to the other world which is ruled by Cronus, the God of Time. Whilst ordinary souls are reborn after some time, the perfected ones are divine and enjoy eternal life in paradise.

Time is qualifier, space is extension, or quantifier. Moment, the worth or meaning of time, is complete, too complete to endure, or to be extension. The quantifier extends, endures, evaporates that completeness. Time is completeness, space, extension, enduring, the convoluted concept of eternity, is always incomplete. The very form of incompleteness.

The intimation is a concept I use advisedly. I am very concerned it will be taken as some tawdry sentiment or spiritualism, I've even been accused of romanticism. The dialectic intimates growing depth of rigor in shared terms that cannot be made explicit because it entails changes in our grasping of terms through a process by which we try in all due rigor to sustain our convictions. But if a broadening lexicon of terms is the entailed result of conserving them, then we can hardly claim this mere sentiment or deny the growing lexicon we share is any less rigorously achieved than the discipline of conserving our premises.

But if a broadening lexicon of terms is the entailed result of conserving them, then we can hardly claim this mere sentiment or deny the growing lexicon we share is any less rigorously achieved than the discipline of conserving our premises. — Gary M Washburn

That is an interesting point of comparison. I will think about it.

By the way, if you mean to respond to a particular post, there is a swoopy reply button that appears next to the time of post text.

His argument is that Harmony is a universal. What is at issue is the difference between the universal and particular. Harmony itself is prior to any particular thing that is in harmony. — Fooloso4

The argument is not about universals. It is a question of whether the activity required to produce, or create, an organized system of parts (the harmony), is necessarily prior to that organized system of parts. Read 93-95.

It definitely is not about universals at all. And another question (at 93b) is the fact that a harmony can be greater or lesser, whereas a soul cannot be any more or less soul than other souls. Which conclusively demolishes the harmony theory. But maybe Fooloso4 is reading a different translation.

Simmias' argument begins here:

“...'one could surely use the same argument about the attunement of a lyre and its strings, and say that the attunement is something unseen and incorporeal and very lovely and divine in the tuned lyre, while the lyre itself and its strings are corporeal bodies and composite and earthy and akin to the mortal. Now, if someone smashed the lyre, or severed and snapped its strings, suppose it were maintained, by the same argument as yours, that the attunement must still exist and not have perished-because it would be inconceivable that when the strings had been snapped, the lyre and the strings themselves, which are of mortal nature, should still exist, and yet that the attunement, which has affinity and kinship to the divine and the immortal, should have perished …” (86a-b)

All of Socrates' arguments are about Forms or Kinds, which Wayfarer calls universals:

So I thought I must take refuge in discussions and investigate the truth of beings by means of accounts [logoi] … On each occasion I put down as hypothesis whatever account I judge to be mightiest; and whatever seems to me to be consonant with this, I put down as being true, both about cause and about all the rest, while what isn’t, I put down as not true.” (99d-100a)

Let's look at the arguments at 93-95.

Socrates asks:

Wouldn't it be more so and more fully a tuning, if could be tuned more fully, and less so and less fully a tuning if it were tuned less so and less fully? (93b)

Socrates does not make the proper distinction between a tuning and what is tuned. It is not more or less a tuning, it is more or less in tune.

Then is this the same with soul? Is one soul, even in the slightest degree, more fully and more so than another, or less fully and less so this very thing - a soul? (93b)

Note the shift from ‘soul’ to ‘one soul’ and 'a soul'. If death is the “perishing of soul” then a soul, the one that perishes, is to the greatest degree "less fully a soul". In addition Socrates earlier raised the problem of the adulterated condition of a soul. (81c) Such a soul is not "less fully a soul". In both cases it is a matter of the condition of the soul, not whether it is a soul.

Next he asks:

'Then what will any of those who maintain that soul is attunement say these things are, existing in our souls- virtue and vice? Are they, in turn, a further attunement and non-attunement? And is one soul, the good one, tuned, and does it have within itself, being an attunement, a further attunement, whereas the untuned one is just itself, and lacking a further attunement within it?'” (93c)

The proper analogy to good and bad souls would be good and bad tunings. Good and bad, virtue and vice, are not things in the soul, they are conditions of the soul, just as sharp and flat are conditions of an attunement. A good soul would be a well tuned soul and a bad soul a poorly tuned one.

“'And moreover, since this is her condition, one soul couldn’t partake of vice or of virtue any more fully than another, if in fact vice is to be lack of tuning and virtue tuning?” (93e)

Socrates has intentionally jumbled terms and Simmias is unable to disentangle them. Attunement itself cannot be non-attunement just as Equal itself cannot be unequal, but just as equal things are more or less equal, attuned things are more or less in tune.

“Therefore it follows from this argument of ours that all souls of all living beings will similarly be good if in fact it’s similarly the nature of souls to be this very thing - souls.” (94a)

The argument is as follows: soul is an attunement, vice is lack of attunement, and so the soul cannot be bad and still be a soul because it would no longer be an attunement. What is missing from the argument is that being in or out of tune is a matter of degree. Vice is not the absence of tuning but bad tuning.

Socrates closes this discussion by citing the authority of Homer, the “Divine Poet” (95a). Socrates appeals to Homer’s divine authority or less gloriously, to the authority of the poet rather than the strength of argument. He uses Homer’s authority in support of his argument against attunement on the grounds of the separation of body and soul, and the rule of the soul over the body. But the passage cited (Odyssey XX 17-18) is not a case of the soul ruling the bodily desire, but of the soul controlling its own anger. In an earlier post I discussed the problem of soul’s desire. In both cases the divide between body and soul cannot be maintained.

Can't there be a harmony in dissonance? A symmetrical contrariety to the prevailing paradigm that erodes that paradigm, while erecting a replacement? We may suppose we are challenging each other, but in a more subterranean sense revising our terms? If so, that revision cannot be identified between the poles of that contrariety. It is as much the product of one as of the other, though opposed to each. Simplistic logic, either/or, is blind to that change. And if reasoning erodes its own premise, then the final continuity of ideas is the act of participating in that change. And of recognizing ourselves and each other in that activity. If the moment of that recognition encompasses that continuity, then which is more timeless? The purified and isolating idea? Or the community in contrariety generated it?

In Lesser Hippias Hippias contrasts Achilles and Odysseus as opposites, and each as the paradigm of the character they embody. Socrates keeps thwarting this strict contrast, even showing how one idea embodies its opposite. Achilles, far from being what courage is, the very form of the idea, is himself a coward. In order to become the idea of courage he has to die. The definition of the idea by the extreme that is so perfect it is not within the real range of its examples. Odysseus would be, not the extreme, but the typical. His great ambition is to be one of the guys. But to achieve this his men have to die. Between the typical, so embedded in the category it says nothing about it, and the extreme, so outside the category that nothing within the category says anything about it, the idea strains to be anything at all. Between cup and lip, many's the slip. But perhaps the slippage is everything, before after all.

The Forms are obviously discussed in the dialogue, but Socrates and Simmias agree on the Forms.

What they disagree on is the nature of soul and whether Simmias' theory of harmony that compares the soul with a harmony is correct.

Socrates and Simmias agree that the theory is an unexamined one that has not been demonstrated and that the theory of recollection which implies that the soul is immortal, is the correct one.

Simmias says:

The argument about recollection and learning, on the other hand, has been provided by means of a hypothesis worthy of acceptance. Because it was said [at 76e - 77a] I think that it is certain that our soul existed even before it entered a body as that there exists in its own right the being that bears the label "what it is". And I have accepted that hypothesis, or so I convince myself, on both sufficient and correct grounds (92d e).

The discussion finally ends at 94e -95a:

Do you suppose that, when he [Homer] wrote those words, he thought of the soul as a harmony which would be led by the conditions of the body, and not rather as something fitted to lead and rule them, and itself a far more divine thing than a harmony?”
“By Zeus, Socrates, the latter, I think.”

“Then, my good friend, it will never do for us to say that the soul is a harmony; for we should, it seems, agree neither with Homer, the divine poet, nor with ourselves.”
“That is true,” said he.

They are not taking Homer as their authority but Homer AND themselves, i.e. the strength of their own argument.

And 94e does not say "the body's desire or anger" but the body's "conditions" or "affections" τα πᾰθήμᾰτᾰ τοῦ σώμᾰτος ta pathimata tou somatos. In other words, the soul is not led or ruled by the conditions undergone by the body.

For this reason, it is agreed (1) that the soul cannot be compared to a harmony, (2) that the theory of recollection is correct, and (3) that the soul is immortal.

The immortality of the soul is reaffirmed at 105e:

In that case, soul is immortal.
Yes, immortal.
Very well, he said. Should we say that this has been proved? What do you think?
Yes, and most sufficiently, Socrates.

And at 114d:

... since the soul turns out to be immortal, I think that for someone who believes this to be so, it is both fitting and worth the risk - for fair is the risk - to insist that either what I have said or something like it is true concerning our souls and their dwelling places [in the other world] ... Anyhow, these are the reasons why a man should be confident about his own soul ...

The discussion ends with the conclusion that the soul is immortal, is incapable of death and destruction, and "retreats" to the other world (Hades) at the death of the body.

The correct translation of 93b is:

Is this true of the soul? Is one soul even in the slightest degree more completely and to a greater extent a soul than another, or less completely and to a less extent?

http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0170%3Atext%3DPhaedo%3Asection%3D93b

The obvious point is that a soul cannot be more or less of a soul than another soul. Therefore a soul is not comparable to a harmony.

This is precisely why the harmony theory is rejected.

When reading Plato’s dialogues it is important to keep in mind who he is talking to and what the circumstances are. Socrates says that under the circumstances it is fitting to:

inquire and speculate as to what we imagine that journey to be like (61e)

But Cebes and Simmias are fearful of death. What they imagine might happen makes them fearful. They want more than fearless inquiry and speculation. In other words, they want the truth only in so far as the truth is comforting.

Socrates says that their fears are childish and that they are in need of incantations to sing away their fears. (77e) Earlier Socrates said that philosophy is the greatest music. (61a) The song that Socrates sings about death will address their fears.

In the Apology Socrates says:

Now being dead is either of two things. For either it is like being nothing and the dead man has no perception of an anything, or else, in accordance with the things that have been said, it happens to be a sort of change and migration of the soul from the place here to another place.

And if in fact there is no perception, but it is like a sleep in which the sleeper has not dream at all, death would be a wondrous gain. (40c-d)

And here he says:

“ For I am calculating - behold how self-servingly!- that if what I’m saying happens to be true, I’m well off believing it; and if there’s nothing at all for one who’s met his end, well then, I’ll make myself so much less unpleasant with lamenting to those who are present during this time, the time before my death.” (91b)

The arguments are all in service of the hope that there is life after death. The image of life after death brings with it another fear, the fear of punishment for wrongdoing. The image thus serves to promote virtue and justice and discourage vice.

The arguments do not hold up to rigorous logical examination, and yet for some they are persuasive.

In the center of the dialogue, both literally and figuratively, is the problem of misologic and the question of what one expects from philosophy. (89d) Does one desire an outcome that provides comfort and reassurance, or does the pursuit of truth mean that one fearlessly inquires independently of a hoped for outcome? The genius of Plato is to satisfy both desires.

There is no need for the arguments in the dialogue to "hold up to rigorous logical examination".

If the arguments are accepted as valid in the dialogue, it is incorrect to claim that they are not.

Readers should not deliberately select imprecise or incorrect translations for the purpose of reading things into them.

Readers should subject their own claims to the same rigorous logical examination to which they subject the dialogue.

If the reading of a dialogue involves or leads to radical skepticism, nihilism, sophistry, evidence-free assumptions, text manipulation and misconstruction, and irrational speculation, then there must be something wrong with the reader.

Socrates makes an ironical comment about Cebes:

“'There goes Cebes, always hunting down arguments, and not at all willing to accept at once
what anyone may say.'” (63a)

It is ironic because this in the opposite of what Cebes does. He simply accepts whatever argument Socrates makes. The following exchange is telling:

“Socrates, the rest seems to me to be beautifully put, but what you say about the soul induces a lot of distrust in human beings. They fear that the soul, once she is free of the body, is no longer anywhere, and is destroyed and perishes on that very day when a human being dies; and that as soon as she’s free of the body and departs, then, scattered like breath or smoke, she goes fluttering off and is no longer anywhere. Of course, if she could be somewhere, herself by herself, collected together and freed from those evils you went through just now, there'd be a great hope - a beautiful hope - that what you say, Socrates, is true. But this point that the soul is when the human being dies and holds onto both some power and thoughtfulness - probably stands in need of more than a little persuasive talk and assurance.”(70a)

Cebes hopefulness amounts to saying that if what Socrates says, that the soul is somewhere herself by herself, is true then is true. Cebes states it in such a way that the latter follows as a conclusion from the former, but both state the same thing.

Socrates responds:

“What you say is true, Cebes, but now what should we do? Or do you want us to tell a more thorough story about these things to see whether what we’re saying is likely or not?””(70a-b)

Socrates proposes telling a more thorough story in order to see if the stories he has told are likely or not. He shifts from Cebes ‘true’ to ‘likely’. He proposes to “investigate it in some such way as this”:

“ … do the souls of men exist in Hades when they have died, or do they not? Now there's an
ancient doctrine, which we've recalled, that they do exist in that world, entering it from this one, and that they re-enter this world and are born again from the dead; yet if this is so, if living people are born again from those who have died, surely our souls would have to exist in that world? Because they could hardly be born again, if they didn't exist; so it would be sufficient evidence for the truth of these claims, if it really became plain that living people are born from the dead and from nowhere else; but if that isn't so, some other argument would be needed.'”(70c-d)

But, of course, some other argument is needed. First, the argument assumes the very thing that is in question. It is question begging. Second, the living come from the living. Now perhaps a soul separate from the senses, a priori, might think that the living come from the dead, but our experience informs us that we are born of living parents. Third, the argument plays on an ambiguity. Hades is the place of the dead, but the whole force of Socrates' arguments is to show that the soul does not die. And so, life does not come from death if the soul does not die.

The argument from opposites concludes with the claim that this movement must be circular:

“And similarly, my dear Cebes, if all things that partake in life were to die, but when they'd died, the dead remained in that form, and didn't come back to life, wouldn't it be quite inevitable that everything would ultimately be dead, and nothing would live? Because if the living things came to be from the other things, but the living things were to die, what could possibly prevent everything from being completely spent in being dead?'” (72 b-d)

Perhaps Cebes is persuaded by this, but it assumes what is still to be proven, the continuation of the soul in death, and ignores the obvious fact of generation of life from the living.