In relation to the eternal question that defines the human condition—namely whether humanity can transcend mortality in an afterlife—, many philosophers have either presupposed or come to the conclusion that a condition of existence after death would surely entail the immortality of the soul. In effect, since any empirical evidence derived from contemporary science would suggest that when the human body perishes so does consciousness, it follows that the immortality of the soul is a necessary condition for any form of existence after death. Thus, coupled with prevalent religious doctrine that advocates living selflessly and piously in this life in order to enter a realm of inconceivable paradise in the afterlife, belief in the immortality of the soul is widespread amongst humanity—serving as justification for countless decisions throughout the course of history. In addition, it is worth noting that the immortality of the soul closely parallels and is sympathetic to a dualist interpretation of the mind-body problem; for if monism was to ever transition from theory to fact, the seemingly logical consensus would speculate that when the body dies the mind and soul would also die. Alas, these fundamental inquiries encapsulating the very purpose and essence of existence have fascinated philosophers since the dawning of man’s self-reflection—and unsurprisingly garnered the attention of the renowned Greek philosophers Socrates and Plato. In particular, Plato’s dialogue, the Phaedo, features Socrates arguing in favor of the immortality of the soul in the presence of companions prior to his impending execution. Socrates hones in on four arguments to support the aforementioned claim—recollection, affinity, criticism of harmony, and form—and herein the focus will be on his arguments from recollection and his criticism of harmony. For in these two highlighted arguments, although characterized by flaws that will be addressed below, Socrates—as personified by Plato—provides the philosophical platform for vital areas of research in areas including the relationship between perception and form acquisition and debates encompassing functionalist, epiphenomenalist, and emergentist interpretations of the relationship between body and soul. In short, while the Phaedo does not adequately prove that the soul is immortal it does not render it implausible, but more importantly the relationship between Socrates’ Theory of Recollection and his criticism of the Harmonia Theory touches upon a multiplicity of integral philosophical and scientific topics that remain essential to man’s yearning for knowledge of the Form of Perfection.     

            Beginning with the argument from recollection, Socrates’ basic assertion is that, since we are unable to encounter perfectly equal objects but still have the knowledge of perfect equality, then we must be recollecting said knowledge from a past life. While ascertaining that this proves the immortality of the soul is overzealous—developed humans can conceptualize perfect equality without ever visualizing such an occurrence—, Socrates’ conviction in recollection has drastically influenced the relationship between perception and form conceptualization—and one could draw connections between Socrates’ dialogue with Meno’s slave and Noam Chomsky’s ‘language acquisition device’ evidencing that Socrates’ theory of recollection, “…is a synoptic  theory of learning, ranging from the inception of speech and thought to the acquisition of knowledge” (Chomsky 1965: 141, Franklin 2005: 291). Accordingly, recollection begins with sense perception, is processed in the mind, and concludes with a connection between sensible particular and Form. Of course, Socrates does not effectively reason how we acquire Form (because we acquired it in our past life), but his argumentation leaves something to be desired anyway—namely the premise that sensible particulars are immediately processed and related to Form implicates that sensible particulars cannot stand alone in thought. Plausibly, one could sense something so revelatory that no premade Form could incorporate the perception. An understanding of Form rather than physical specificities may indeed provide the gateway to attaining true wisdom, beauty, etc., but the inference that every sense perception is intrinsically thought of in relation to Form appears troublesome.

In order to refute the ‘unique particular’ example, developed humans would have to have acquired ‘universal Forms’ of sorts—essentially the number of Forms it takes to connect any sensible particular. Plato appears to recognize that an explanation of ‘concept acquisition’ is necessary (75a5-8, 75b4), and, in contrast to Socrates, that perception plays a key role in philosophical inquiry. Franklin provides an intriguing point in referencing Plato’s differentiation between remembering a person from a picture and recollecting a Form from said picture, “…while a comparison of image to original may be necessary…Plato does not think such a comparison necessarily accompanies the ordinary recollection or predication of Forms. Thus, Socrates' attribution of simultaneity and necessity in the introduction of NC [necessary correlation] applies only to the familiar examples” (Franklin 2005: 302). In this view, again contrasting Socrates’ but certainly influenced by his theorizing, the correlation between sense perception and (pre-established) Form is compatible with mere sense perception—and perhaps subsequent creation of a new Form—when a Form for such a sense perception does not exist in the respective recipient’s cognition at the moment of perception. Regarding whether it is plausible to believe that a ‘unique’ sense perception leads to the creation of a new Form, Socrates’ insists that sensible equals, “appear to be equal to one thing and unequal to another,” whereas the Equal Itself (the Form) cannot possibly be unequal (74b7-9, 74c1-2). He deducts that one cannot grasp Form from particulars that can be dually equal and unequal—and thusly Socrates would deny the premise that one can grasp or create Form based off of merely particulars. And one could surmise that Socrates would make this claim; if one could deduct Form from particulars, then recollection would be used—but never as a necessity—, and there would definitely be no need for an immortal soul. So, if one cannot grasp Form from perception according to Socrates, one must wonder what Socrates’ explanation is for the acquisition of Form—apart from that we inherited the ability from a past life. Ironically enough, Socrates begins by expressing a view that is similar to Kantian apperception and synonymous with contemporary ‘inductive generalization,’ when he claims, “It is because of the way sensible equals appear to be both equal and unequal that we know them to be different from and deficient in comparison to the Equal itself. It is in this sense that the realization comes from the senses” (74a-76c translation from Franklin). But, because of his sentiment that sensible particulars are inadequate in grasping form, Socrates later reasons, “…somehow we took up the knowledge of it, the Equal, what it is…” (75b4-5). Therefore, Socrates actually comes to the more plausible conclusion, but due to proposing a causal relationship between the immortality of the soul and recollection, he could not claim that we can inductively generalize upon perception.

Moving on to Socrates’ criticism of harmony, his basic intention is to disprove that the mind emerges from the physical (emergentism) because, in his view, the mind has causal power over the physical. In other words, if the soul is like harmony then the soul supervenes on the body—hence there could be no difference in mental states without there being a difference in physical states. Similar to his theory of recollection, Socrates’ argument appears flawed since it is plausible for the mind to come into existence simultaneously or after the physical body and still have causal precedence, but his discussion of harmony has had a profound effect on the study of mental causation. For instance, while discussing the possibility of the mind being independent from the body, Aristotle writes, “…in the absence of any external cause of terror we find ourselves experiencing the feeling of a man in terror” leading Langton to infer that “the affections of the soul are ‘enmattered accounts’” (403a24, Langton 2000: 17). This conclusion seems to lead to a multiply realizable interpretation in which the mind is supervening upon the body yet still autonomous—marrying functionalism and physicalism if you will. Socrates, unlike Aristotle, denies such supervenience—and holds an extreme dualist opinion in comparison to modern functionalism that assumes the soul cannot exist without a body. The body only restricts the soul’s true purpose according to Socrates. Aristotle later writes that a harmony “lacks the power of originating movement,” which ultimately must be controlled by the mind (407b34). This establishes a necessary relation between mind and body (‘homonymy principle’), but remains compatible with the contingent relation of multiple realizability. For matter cannot fail to fulfill the function, but the function could still be fulfilled without matter—although this is not realized while the soul is ‘trapped’ within the body. Aristotle of course eventually argues that the soul is necessarily embodied—incompatible with Socrates’ argument—, but where the compatibility of homonymy and multiple realizability ultimately leaves Socrates is that the mind dictating causation in conjunction with emergentism is also plausible.

Prior to revisiting the Phaedo directly, the ramifications of adopting supervenience and multiple realizability should be considered. Caston writes that there are two positions that allow this: “contemporary epiphenomenalism,” advocating the supervenience and inefficacy of the mental, and “emergentism, advocating the supervenience and efficacy of the mental (Caston 1997: 314-317). Socrates in the Phaedo, as aforementioned, denies the supervenience of the mental but adheres to the efficacy of the mental premise. As acknowledged by Caston, “…on their own, physical powers do not bring about everything that occurs in the realm of nature,” and this opens the door for the study of philosophy, theology, or—in Socrates’ case—the proposition of the immortality of the soul (Caston 1997: 319). But, when Simmias claims that Socrates’ argument against harmony is inadequate, Simmias notes that the soul is a “tempering” of elemental powers as “Socrates himself well knows” (86b5-7) Accordingly, to ‘harmonics’ whom Simmias is identifying with, tuning is multiply realized and not caused by the instrument’s physical state (although supervening upon it). Eventually, just like how Socrates indirectly supported ‘inductive generalization, he also appears to indirectly support supervenience of the mind on the body when he says to Simmias, “Then it's not characteristic of a tuning to lead whatever it happens to be compounded from, but to follow” (93a5-7). Socrates realizes that musical events supervene on physical events, so he is forced to deny that the soul is like harmony—even though the soul does seem to ‘temper’ like Simmias predicates. Therefore, Socrates is limited to supporting a form of dualist downward causation that supposes the soul is changeless, does not temper with the body, and is immortal. But the soul does appear to temper with sense perception and its interrelation with cognition, so the argument for the immortality of the soul from this perspective is not persuasive either.

In conclusion, Socrates’ arguments in the Phaedo for the immortality of the soul, specifically recollection and harmony, do not shed definitive light on whether the soul is immortal. In fact, on both accounts Socrates verges upon coming to conclusions advocating inductive generalization and emergentism—but they would make his argument for the immortality of the soul less plausible. Regardless, what the arguments in the Phaedo do accomplish is a priceless platform for philosophical and scientific discussion; in sum, granting philosophers can still debate whether the soul is immortal, what cannot be debated is that the contributions of Plato and Socrates in the Phaedo stimulate theorizing about the relationship between mind and body, knowledge and immortality, and for that humanity should consider themselves eternally indebted.  


Aristotle, Translated by Joel Sachs., Aristotle’s On the Soul and On Memory and Recollection. Santa Fe, USA: Green Lion Press. (2001).

Caston, V., “Epiphenomenalisms, Ancient and Modern”. The Philosophical Review. 106. 3. (1997). 309-363.

Chomsky, N., “Aspects of the Theory of Syntax”. MIT Press. (1965). 141.

Franklin, L., “Recollection and Philosophical Reflection in Plato’s “Phaedo””.  

Langton, R., “The Musical, the magical, and the mathematical soul”. History of the mind-body problem. (2000). 15-33.

Plato, Translated by G.M.A. Grube., Phaedo. Indianapolis/Cambridge: Hackett Publishing Company, Inc. (2002). 93-154.

Frankfurt, Harry. “Alternate Possibilities and Moral Responsibility”. Journal of Philosophy. 820-39. 1969.