On the Soul: Plato’s Four Arguments for Immortality in the Phaedo

On the Soul: Plato’s Four Arguments for Immortality in the Phaedo

The Soul and its salvation are central to various systems of religion and esoteric philosophy. Yet, despite its centrality, the doctrine of the immortality of the soul is often implicitly assumed rather than explicitly argued for. Plato’s Phaedo, which recounts Socrates last dialogue before his execution at the hands of the Athenians, makes an important contribution in this regard, since it offers a series of arguments for the immortality of the soul. In it, Socrates attempts to comfort his friends as they lament his impending death. But he comforts them not only through mythos, but also through logos, setting forth four arguments for the soul’s immortality.

In Plato’s day, as in ours, many dismissed the doctrine of the immortality of the soul as implausible. Cebes, one of Socrates’ interlocutors, observes that the people of his day, like contemporary materialists, contend that the soul dies with the body, dissipating like smoke. He observes:

“They [ordinary people] think that after it [the soul] has left the body it no longer exists anywhere, but that it is destroyed and dissolved on the day the man dies, as soon as it leaves the body; and that, on leaving it, it is dispersed like breath or smoke, has flown away and gone and is no longer anything anywhere” (70a Trans. Grube).

According to this view, the soul, upon leaving the body, dissipates into its constituent parts and thereby ceases to exist. Cebes observes that, in light of the prevalence of this opinion, if he and his friends are to have a rational faith in the belief that Socrates will continue to exist after the death of his body, a persuasive argument is needed for the claim that “the soul still exists after a man has died and that it still possesses some capability and intelligence” (70b). Socrates gladly obliges this request and spends his last hours on earth setting forth four arguments for the immortality of the soul. Let’s examine each of these in turn.

1. Generation through Opposites

Socrates begins by invoking the Pythagorean doctrine of metempsychosis, the transmigration of the soul. He notes that “we recall an ancient theory that souls arriving there (the underworld) from here, and then again that they arrive here and are born here from the dead” (70c). On this Pythagorean view souls go to Hades after death and then reincarnate in new bodies. Socrates then points out, that if this story were true, then it would entail that the soul continues to exist after the death of the body, “for they could not come back [i.e. be reincarnated] if they did not exist” (70d). If each new life is the reincarnation of a soul from Hades, then souls must be able to exist after the death of particular bodies.

Yet, this argument would remain unconvincing to those who do not already believe in reincarnation. Socrates thus attempts to provide an argument for such a view. He observes that when we look to the world of becoming, we see that things come to be from their opposites. Consider the case of the acceleration of my car as I drive it on the highway. As it enters the highway, my car is traveling slowly, but after I have entered it, I press the gas and the car accelerates and moves quickly. At this point, my car has come to be fast. But, before it was so, it was slow. Conversely, consider my what happens when my car decelerates. As I exit the highway and hit the brakes, my car slows down. My car has come to be slow. But this state of being slow was preceded by one of being fast (71a).

Or again, consider the case of large and small. A tree might be large, but before it was large, it was first a small seed. And, if the tree were to be torn apart in a storm, and become small as a result, its being small would be preceded by being large. (71a).

Thus, when we examine the world of becoming, it looks as if things come from their opposites. “For all things which come to be”, these things “come to be from their opposites if they have such” (70e). Indeed, when we look at nature, we see that it is governed by cycles of opposing processes. Between each pair of opposites “there are two processes: from the one to the other and then again from the other to the first.” (71b). For example, night, follows day, and day follows night. Or again, sleep follows waking, and waking follows sleep. Socrates argues that if nature were not arranged by such circular processes, but as a straight line, it would terminate in a single state. For example, light would cede to darkness and then darkness would reign forever. But this is not what we experience in nature.1

“If the two processes of becoming did not always balance each other as if they were going round in a circle, but generation proceeded from one point to its opposite in a straight line and it did not turn back again to the other opposite or take any turning, do you realize that all things would ultimately be in the same state, be affected in the same way, and cease to become?” (72a-b).

Now, consider death and life. These are opposites and are governed by the processes of dying and coming to life. But this means that dying, must always be followed by coming to life. In this manner, we have a picture of the natural world that comports with the Pythagorean doctrine of metempsychosis. If coming to life, is a coming to life again from a state of being dead, then people must be able to continue to exist after death.

2. Recollection

Socrates’ second argument turns on the Platonic doctrine of recollection. According to Plato, all knowledge is a remembering of the invisible realm of the forms. Socrates defines ordinary recollection as follows:

A mind recollects when it “sees or hears or in some other way perceives one thing and not only knows that thing but also thinks of another thing of which the knowledge is not the same but different” (73c).

For example, one might hear the music of a lyre and come to know it as such. But, if one was accustomed to listening to the lyre with one’s old lover, then that music might also call to mind that old love. The music, given that it is a series of notes and not a human being, does not resemble the lover, yet it still suffices to call him or her to mind. In this manner, one recollects one’s lost love through the music (73e).

Now, on the Platonic view, all real knowledge gained from the sensible world involves such recollection. Though Plato discusses this doctrine more thoroughly in the Meno, he nonetheless offers a couple of brief arguments here. First, Cebes points to how people learn new truths. He argues that “when men are interrogated in the right manner, they always give the right answer of their own accord, and they could not do this if they did not possess the knowledge and the right explanation inside them. Then if one shows them a diagram or something else of that kind, this will show most clearly that such is the case” (73a-b). For example, one might be untrained in geometry, but if questioned in the right manner, come to discover geometrical truths that he or she in some sense knew all along. The seeing the diagram is not the same thing as the knowledge of the geometrical truth, but it nonetheless calls it to mind in recollection.

Second, Socrates offers an argument from the deficiencies of empirical cognition. We might, for example, look at a couple of sticks and see that they are equal, and thereby bring to mind the form of Equality. As empirical objects, the sticks are not truly equal, having slightly different lengths and weights. Yet, these sticks still suffice to call to mind the form of Equality, and this calling to mind, claims Socrates, is a recollection. Indeed, we might forgo the aspect of comparison between two objects and make a similar argument from considering singular objects. I might, for instance, attempt to draw an equilateral triangle and see that it is is defective. But in seeing that this is a defective instance of a triangle, I need to have the perfect form of triangle in mind in order to make the comparison. So, seeing the defective triangle, allows me to recall the perfect form of the Triangle.

After offering some brief arguments for the doctrine of recollection, Socrates goes on to use it to argue for the claim that the soul can survive the death of the body. For, if all true knowledge is recollection of the forms, then we must have been previously acquainted with them. Furthermore, since the forms are invisible and immaterial, we must have been acquainted with them while we were ourselves existing in such a state. Thus, since we have previously existed in a non-corporeal state, we do not necessarily perish with our bodies (76a-e).2

3. Kinship to the Invisible Realm

Socrates third argument appeals to the Platonic distinction between the visible world of matter and the invisible world of the forms. Socrates observes that we must “ask ourselves”:

“What kind of thing is likely to be scattered [and thus destroyed]? On behalf of what kind of thing should one fear this, and for what kind of thing should one not fear it? We then should examine to which class the soul belongs, and as a result either fear for the soul or be of good cheer.” (78b).

Socrates argues that when we examine what is scattered and destroyed, we see that it is physically composite. Composite things, because they are composed of various parts, can be destroyed by separating those parts. A sand castle, for example, is made of many grains of sand. So, when the tide comes in and separates its constituent parts, the sand castle itself is destroyed. It thus seems that what “is composite and a compound by nature” is “liable to be split up into its component parts”, and, conversely, “that which is non-composite…is not likely to be split up” (78c). If something has no physical parts, it cannot be broken down and destroyed in this manner.

Now given the Platonic distinction between the invisible world of the forms and the visible world of material objects, it is clear which of these is likely to have physical parts and thus be likely to be destroyed. Material objects are composed of physical parts which change with time, thus coming into and out of existence. The realm of the forms, in contrast, remains eternally as it is. The forms are “ever the same and in the same state.” “The Equal itself, the Beautiful itself, each thing in itself, and the real” are never “affected by any change whatever”. “Each of them…being uniform by itself, remain the same and never in any way tolerate any change whatever.” (78d).

Since we are composed of both body and soul, we must inquire into what kinds of realities they are akin to. Is the body more like the sensible world of matter or the invisible world of forms? And which is the soul akin to? Socrates and his interlocutors think the answer is obvious. The body is akin to the visible world. You can see your body. It changes and comes into and out of existence. The soul, on the other hand, is akin to the invisible, since you cannot observe it with your physical senses (79b-c). And there is a further parallel between the soul and the invisible world in that both involve normative rule. The gods in the invisible realm should rule the visible world, and the soul should rule the body (80a). Hence, “the soul is most like the divine, deathless, intelligible, uniform, indissoluble, always the same as itself, whereas the body is most like that which is human, mortal, multiform, unintelligible, soluble and never consistently the same.” And, thus, it is “natural for the body to dissolve easily, and for the soul to be altogether indissoluble, or nearly so.” (80b-c).

4. The Exclusion of Opposites

Socrates’ final argument is grounded in the exclusion relations between forms. Whereas the realm of Becoming is governed by a cyclical process where opposites are generated from opposites (e.g. day coming from night and night coming from day), the realm of Being is governed by exclusion relations.3 Every form is what it is and necessarily excludes its opposite. We can think of this as a kind of metaphysical correlate to the principle of non-contradiction. The logical principle of non-contradiction maintains that: ~(A&~A). We cannot assert both A and ~A at the same time and in the same respect. And we can think of this logical principle of being grounded in the property of A itself. Being A excludes all that is not A.

Consider for example the properties of hot and cold (103c). Hot, by its very nature, excludes the cold, and cold the hot. Nothing will be both cold and hot at the same time and in the same respect. If something is hot, then it will, insofar as it is hot, “never admit” (102e) the hot. When the cold approaches, it will either “flee and retreat whenever its opposite”, the cold, “approaches, or is destroyed by its approach.” (102e). To the extent that something is hot, it cannot be cold, and to the extent that something is cold, it cannot be hot.

Socrates goes on to note that not only are simple forms organized according to their exclusion relations, but more complex essences are also arranged in this manner. Consider, for example, fire and snow. Though not themselves the forms of hot and cold, they nonetheless bear an essential relation to them. Fire is essentially hot, and snow is essentially cold (103d). If fire were no longer hot it would cease to exist, and so too would snow if it were no longer cold. “Being snow it will not admit the hot, as we said before, and remain what it was and be both snow and hot, but when the hot approaches it will either retreat before it or be destroyed” (103d).

Or, at a more abstract level, consider the numbers two and three and their relations to the forms Even and Odd. Two is essentially even, and three essentially odd. It is impossible for three to be what it is and be even or for two to be what it is and be odd (104b-c). Socrates observes, “what the form of three occupies must not only be three but also odd….The opposite Form to the Form that achieves this result could never come to it….So the Form of Even will never come to three… [and] three has no share in the Even.” (104d-e).

Socrates then uses this metaphysical principle to argue for the immortality of the soul, by observing that the soul is that in virtue of which living things live. Socrates inquires:

“If you should ask me what coming into a body, makes it hot, my reply would be… fire, and if you ask me what, on coming into a body, makes it sick, I will not say sickness but fever. Nor, if I asked the presence of what in number makes it odd, I will not say oddness but oneness, and so with other things…Answer me then…what is it that, present in a body, makes it living?” (105b-c)

To this, Cebes responds, “a soul” (105c). The soul is what differentiates living bodies from corpses, birds from rocks, and trees from decaying soil. Things are alive by virtue of having souls. “Whatever the soul occupies, it always brings life to it.” So, the soul is essentially related to the form of life, just as fire is essentially related to the form of heat, or three is essentially related to the form of oddness. Furthermore, life and death are contrary properties. To the extent that something is living, it cannot be dead, and to the extent that something is dead, it cannot be living (105d).

Hence, since the soul essentially excludes death, it is “deathless” (105e). And, in virtue of being deathless, the soul is indestructible. Socrates argues:

“If the deathless is also indestructible, it is impossible for the soul to be destroyed when death comes upon it. For it follows from what has been said that it will not admit death or be dead, just as three, we said, will not be even nor will the odd; nor will fire be cold, nor the heat that is in the fire.” (106b).

And it seems plausible for this to be the case, since “hardly anything could resist destruction if the deathless, which lasts forever, would admit destruction….All would agree…that the god, and the form of life itself, and anything that is deathless, are never destroyed” (106d).

Hence, “when death comes to man, the mortal part of him dies, it seems, but his deathless part goes away safe and indestructible, yielding the place to death…Therefore the soul…is most certainly deathless and indestructible and our souls will really dwell in the underworld” (106e-107a).

And, so, armed with these four arguments, and the rational faith that they ground, Socrates goes to face his death with confidence. Knowing that he has done his best to follow the gods in this life, and trusting them to guide him to yet greater and clearer visions in the realms beyond our own.

Peter Yong, Ph.D.

[The image used in the thumbnail of this essay is of the world ash tree Yggdrasil. It is in the public domain and can be found here. https://commons.wikimedia.org/wiki/File:Yggdrasil.jpg ]


1While the cyclical view of nature seemed obvious to Socrates, the linear point of view is taken as commonsensical to many today. It is taken as a matter of course that universe will yield to entropy and the darkness and death will reign forever. Yet, I would ask one to consider which of these views better fits our experience of the natural world. It seems like if the linear point of view ending in death is correct, it must be for reasons other than ordinary experience. If that is the case, it is important to determine what exactly the scientific theory is that is meant to epistemically override ordinary experience, and determine whether that theory is indeed the only justified scientific option.

2“If those realities we are always talking about exist, the Beautiful and the Good and all that kind of reality, and we refer all the things we perceive to that reality, discovering that it existed before and is ours, and we compare these things with it, then, just as they exist, so our soul must exist before we were born.” (76d-e).

3“You have bravely reminded us, but you do not yet understand the difference between what is said now and what was said then, which was that an opposite thing came from an opposite thing; now we say that the opposite itself could never become opposite to itself, neither than in us nor that in nature. Then, my friend, we were talking of things that have opposite qualities and naming these after them, but now we say that these opposites themselves, from the presence of which in them things get their name, never can tolerate the coming to be from one another.” (103a-b).

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