Plato's Phaedo: Philosophy as Preparation for Death › The Four Arguments for Immortality

The heart of the *Phaedo* consists of four arguments for the soul's immortality, each building on the previous and responding to objections raised by Simmias and Cebes. ## The Argument from Opposites Socrates begins with a general principle: opposites come from opposites. The larger comes from the smaller; the awake from the asleep; the hot from the cold. We observe this everywhere in nature. By analogy, the living come from the dead, and the dead from the living. If this were not so (if the living came from the dead but the dead did not return to life) then eventually all things would be dead and nothing would live. The cycle of nature requires reciprocity. This argument has notable weaknesses. The analogy between physical opposites (hot/cold, large/small) and life/death is questionable. Physical opposites are properties that things can gain and lose while continuing to exist. But death seems to be the cessation of the thing itself, more than a change of property. The argument may establish a cycle of generation and corruption in nature, but whether individual souls participate in this cycle remains uncertain. Socrates seems aware of these limitations. He quickly supplements this argument with others. ## The Argument from Recollection The second argument is more substantial. Socrates observes that we have concepts of perfect equality, perfect beauty, perfect justice, yet no physical object fully exemplifies these concepts. Two sticks may be roughly equal in length, but they are never perfectly equal. A person may be beautiful, but their beauty fades and falls short of perfect beauty. Where do these concepts come from? Not from sensory experience, which only shows us imperfect instances. We must have acquired them before birth, when the soul existed without a body and could contemplate the Forms directly. Learning is therefore recollection: the sensory experience of imperfect instances triggers the soul's memory of the perfect Forms it once knew. > We must have acquired our knowledge of equality before we started seeing and hearing and using our other senses, and we must have possessed it before we were born. This argument establishes that the soul existed before this life. But Cebes objects that it does not prove the soul survives death. Perhaps the soul existed before embodiment but is destroyed when the body dies, like a weaver who outlives many cloaks but eventually perishes. ## The Argument from Affinity To address this objection, Socrates argues that the soul resembles eternal things more than perishable ones. Reality divides into two kinds: the visible, changing, composite, and mortal; and the invisible, unchanging, simple, and immortal. The body clearly belongs to the first category. But the soul grasps invisible truths, reasons about unchanging principles, and seeks what is eternal. It has more affinity with the second. What is composite can be decomposed and destroyed. What is simple cannot. The soul, being more like the simple and eternal, is unlikely to be destroyed when the body dies. It will continue to exist, either ascending to contemplate the Forms if it has been purified by philosophy, or remaining attached to the physical realm if it has been corrupted by bodily desires. :::: {.callout-warning title="Common Misconception"} The affinity argument does not claim that the soul is identical to the Forms or that it is absolutely indestructible. It argues that the soul is more like eternal things than perishable things, making its survival after death probable. Plato is careful to distinguish the soul from the Forms themselves. :::: ## The Final Argument: Soul as Life The culminating argument responds to a striking objection from Simmias: perhaps the soul is just a harmony of the body, like the tuning of a lyre. The harmony depends on the lyre and perishes when the lyre is destroyed. Perhaps the soul depends on the body and perishes with it. Socrates offers several objections to this view. First, if the soul is a harmony, it could not have existed before the body, contradicting the argument from recollection. Second, harmonies admit of degrees (more or less in tune), but souls do not seem to admit of degrees of soul-ness. Third, and most importantly, the soul can oppose the body's desires, but a harmony cannot oppose the instrument that produces it. The final argument builds on this last point. The soul is the principle of life. Whatever has a soul is alive; when the soul departs, the body dies. But if the soul is essentially life-giving, it cannot admit death into itself, just as fire cannot admit cold or odd numbers cannot admit evenness. When death approaches, the soul does not become dead. It departs, continuing to exist elsewhere. > The soul is immortal and imperishable, and our souls will truly exist in Hades.