We all wonder what happens when we die. Do we simply cease to exist when our bodies perish, or does our existence continue through our souls’ survival in a realm beyond the physical? If there is indeed an afterlife, how can we determine whether we will find happiness or sorrow there? Different religions offer diverse perspectives on this profound topic, but today we delve into philosophical reflections on these questions. We will focus on Plato’s insights, presented in his dialogue Phaedo.
Plato (428/427–348/347 BC), a towering figure in ancient Greek philosophy, laid the foundations of Western thought and continues to influence contemporary debates. Born in Athens, Plato was a disciple of Socrates, the central character in most of his dialogues. In 387 BCE, Plato founded the Academy, a prestigious center of learning that attracted diverse scholars and thinkers, including Aristotle, a philosopher who would also become highly influential. Plato’s works, written in the form of dialogues, explore fundamental questions about ethics, politics, epistemology, aesthetics, and metaphysics. Plato’s profound impact on Western thought is exemplified by what the British philosopher A.N. Whitehead said about him: “The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato.”
In Plato’s dialogue, the Phaedo, we are privy to the final hours of Socrates before his death by hemlock. Narrated by Phaedo, a close friend and devoted disciple of Socrates, the dialogue recounts the philosophical discussions that unfolded, delving into profound metaphysical and ethical questions about the nature of the soul, life, and death. The central theme of these discussions—and the focus of our exploration here—is the concept of the soul’s immortality. We will concentrate on key passages from the dialogue that showcase Socrates’ engagement with his friends and followers, most notably Simmias and Cebes, as they grapple with the profound implications of mortality and the potential for an afterlife. For those intrigued, the complete Phaedo can be accessed here.
Death – Plato understands this as the soul’s separation from the body.
Immortality of the Soul – Unlike the body, the soul is not subject to physical death, because it is immortal and indestructible.
Recollection – The soul existed prior to birth; during this time it learned everything, and hence all learning is only recalling what we already know.
Philosophy – The practice of preparing the soul for death by training it to think and exist independently of the body.
Forms – The perfect, divine, and intelligible entities that exist independently of the physical world. They are comprehensible only through reason, not through our senses, and their existence explains the properties of objects in the physical world. For example, consider the concept of beauty. We recognize beauty in various objects and experiences – a sunset, a painting, a person – but what is beauty itself? Plato would argue that there exists a Form of Beauty, an eternal and unchanging essence that all beautiful things participate in. Similarly, the concept of justice is not tied to any particular law or action but exists as a Form of Justice, an ideal standard against which we can measure the justness of our laws and actions.
In 4th-century-BCE Athens, opinions on the soul varied: some believed in its mortality, others in its immortality. Consequently, Socrates’ pupils were perplexed about what transpired after death. However, Plato’s Socrates, facing death, is convinced of the soul’s immortality and is confident that after he dies his soul will join the gods because of his virtuous life, dedicated to philosophy. He maintains that people should only fear death if they have lived immorally. To prove the immortality of the soul, he presents four arguments, which posit that the soul not only predates birth but also endures beyond an individual’s demise, due to its eternal nature and indestructibility. We’ll call the first argument The Argument from Opposites.
70c–72e
“Now,” said he, “if you wish to find this out easily, do not consider the question with regard to men only, but with regard to all animals and plants, and, in short, to all things which may be said to have birth. Let us see with regard to all these, whether it is true that they are all born or generated only from their opposites, in case they have opposites, as for instance, the noble is the opposite of the disgraceful, the just of the unjust, and there are countless other similar pairs. Let us consider the question whether it is inevitable that everything which has an opposite be generated from its opposite and from it only. For instance, when anything becomes greater it must inevitably have been smaller and then have become greater.”
[…]
“Now,” said Socrates, “I will tell about one of the two pairs of which I just spoke to you and its intermediate processes; and do you tell me about the other. I say one term is sleeping and the other is being awake, and being awake is generated from sleeping, and sleeping from being awake, and the processes of generation are, in the latter case, falling asleep, and in the former, waking up. Do you agree, or not?”
“Certainly.”
“Now do you,” said he, “tell me in this way about life and death. Do you not say that living is the opposite of being dead?”
“I do.”
“And that they are generated one from the other?”
“Yes.”
“Now what is it which is generated from the living?”
“The dead,” said he.
“And what,” said Socrates, “from the dead?”
“I can say only one thing—the living.”
“From the dead, then, Cebes, the living, both things and persons, are generated?”
This passage discusses the concept of opposites and the process of generation. Socrates claims that everything with an opposite is generated from that opposite. He uses examples to illustrate this concept: sleeping versus being awake and living versus being dead. Just as wakefulness arises from sleep and vice versa, Socrates contends that the living emerge from the dead, and the dead from the living. This cyclical interplay suggests that the souls of the deceased must exist in some realm before being reborn into the world of the living. This implies the pre-existence of the soul, supporting the idea of its immortality.
Life is a stage for a ceaseless interplay of opposites. But how often do we observe this in our own lives? For one day, become a detective of duality. Identify at least three pairs of opposites you encounter. Does the idea that opposites create each other always hold true? Can you think of any exceptions? Bonus points if you can explain why!
In further support of his claim that the soul is immortal, Socrates presents the Argument from Recollection.
72e–77a
[…] Cebes rejoined, “if it is true, Socrates, as you are fond of saying, that our learning is nothing else than recollection, then this would be an additional argument that we must necessarily have learned in some previous time what we now remember. But this is impossible if our soul did not exist somewhere before being born in this human form; and so by this argument also it appears that the soul is immortal.”
[…]
“Now if we had acquired that knowledge before we were born, and were born with it, we knew before we were born and at the moment of birth not only the equal and the greater and the less, but all such abstractions? For our present argument is no more concerned with the equal than with absolute beauty and the absolute good and the just and the holy, and, in short, with all those things which we stamp with the seal of absolute in our dialectic process of questions and answers; so that we must necessarily have acquired knowledge of all these before our birth.”
“That is true.”
“But, I suppose, if we acquired knowledge before we were born and lost it at birth, but afterwards by the use of our senses regained the knowledge which we had previously possessed, would not the process which we call learning really be recovering knowledge which is our own? And should we be right in calling this recollection?”
“Assuredly.” […]
Plato’s Theory of Recollection was first introduced in his dialogue Meno in the form of a myth. In the Phaedo, Socrates presents the Theory of Recollection as an argument for the immortality of the soul. The theory suggests that learning is actually the recollection of knowledge that the soul acquired before birth. Socrates argues that our ability to understand abstract concepts or the Forms, such as equality and beauty, implies that we must have known about these entities before birth, as we cannot gain such knowledge from our experiences of the physical world. Therefore, the theory leads to the conclusion that the soul existed before birth and is immortal, as it must have acquired this knowledge in its previous existence.
Premise 1: All that we recollect was acquired during a previous period.
Premise 2: We perceive something with our senses (e.g., equal sensible objects) and conceive something different with our reason (e.g., the Equal itself, the Form of Equal).
Premise 3: We first know the abstract concepts (such as the Form of Equal) and then perceive the sensible objects that share the same name (like two equal pieces of wood).
Premise 4: We have senses and bodies at birth, and we perceive sensible objects after our birth.
Conclusion 1: Therefore, knowledge of the Forms precedes our birth.
Premise 5: If we knew the Forms before our birth, then we would have acquired this knowledge through our souls and not our bodies.
Conclusion 2: So, our souls precede our birth.
However, the pre-existence of the soul is insufficient to prove its immortality; it must also be argued that the soul persists after the body’s death. Socrates intends to establish this with the next two arguments he presents.
Despite their acceptance of the soul’s pre-existence, Simmias and Cebes still question whether the soul survives the death of the body. In response to their challenge, Socrates combines the preceding two arguments.
77c–77d
“It has been shown, Simmias and Cebes, already,” said Socrates, “if you will combine this conclusion with the one we reached before, that every living being is born from the dead. For if the soul exists before birth, and, when it comes into life and is born, cannot be born from anything else than death and a state of death, must it not also exist after dying, since it must be born again? So the proof you call for has already been given.”
Socrates interweaves the Argument from Opposites and the Recollection Argument to illuminate the enduring essence of the soul. The cyclical nature of opposites, as exemplified by the transition between life and death, hints at the soul’s continuous existence. The Recollection Argument, which posits that the soul possesses innate knowledge of the Forms, further supports this idea by implying the soul’s pre-existence. By synthesizing these arguments, Socrates constructs a compelling philosophical case for the soul as an eternal entity, transcending the physical world and intimately connected to the divine. The concept of the soul’s immortality, thus established, serves as a foundation for Socrates’ subsequent exploration in the Argument from Affinity.
Socrates proceeds by employing the Argument from Affinity to elucidate the soul’s immortal and divine essence, in contrast to the body’s mortal and material attributes.
78b–80e
[…] “Now is not that which is compounded and composite naturally liable to be decomposed, in the same way in which it was compounded? And if anything is uncompounded is not that, if anything, naturally unlikely to be decomposed? […]
“Then it is most probable that things which are always the same and unchanging are the uncompounded things and the things that are changing and never the same are the composite things?”
“Yes, I think so.”
“Let us then,” said he, “turn to what we were discussing before. Is the absolute essence, which we in our dialectic process of question and answer call true being, always the same or is it liable to change? Absolute equality, absolute beauty, any absolute existence, true being—do they ever admit of any change whatsoever? Or does each absolute essence, since it is uniform and exists by itself, remain the same and never in any way admit of any change?”
“It must,” said Cebes, “necessarily remain the same, Socrates.”
“But how about the many things, for example, men, or horses, or cloaks, or any other such things, which bear the same names as the absolute essences and are called beautiful or equal or the like? Are they always the same? Or are they, in direct opposition to the essences, constantly changing in themselves, unlike each other, and, so to speak, never the same?”
“The latter,” said Cebes; “they are never the same.”
[…]
“And you can see these and touch them and perceive them by the other senses, whereas the things which are always the same can be grasped only by the reason, and are invisible and not to be seen?”
“Certainly,” said he, “that is true.”
“Now,” said he, “shall we assume two kinds of existences, one visible, the other invisible?”
“Let us assume them,” said Cebes.
“And that the invisible is always the same and the visible constantly changing?”
“Let us assume that also,” said he.
“Well then,” said Socrates, “are we not made up of two parts, body and soul?”
“Yes,” he replied.
“Now to which class should we say the body is more similar and more closely akin?”
“To the visible,” said he; “that is clear to everyone.”
“And the soul? Is it visible or invisible?”
“Invisible, to man, at least, Socrates.”
[…]
“And the body?”
“Is more like the other.”
[…]
“Then see, Cebes, if this is not the conclusion from all that we have said, that the soul is most like the divine and immortal and intellectual and uniform and indissoluble and ever unchanging, and the body, on the contrary, most like the human and mortal and multiform and unintellectual and dissoluble and ever changing.”
The Argument from Affinity establishes a fundamental distinction between two realms: the visible, transient world of physical bodies and the invisible, eternal realm of the soul. The soul, being invisible and unchanging, shares a greater affinity with the divine and immortal Forms than with the perishable body. This suggests that while our bodies are subject to decay and dissolution, the soul, mirroring the eternal nature of the Forms, persists as an indestructible entity.
The Affinity Argument introduces a fundamental dualism between the immortal, unchanging soul and the mortal, changing body. This argument serves as a cornerstone of Plato’s philosophy, intricately linked to his theories of knowledge and ethics. The Affinity Argument establishes the soul’s unique capacity to grasp eternal truths, known as the Forms, through reason and philosophical inquiry. For Plato, this pursuit of knowledge transcends mere intellectual curiosity; it represents a moral imperative that guides the soul toward virtue. In contrast, the body, bound to the material world and its fleeting pleasures, can obstruct this pursuit. Thus, philosophical life is framed as a process of liberating the soul from the constraints of the body, enabling it to ascend to the realm of the Forms.
Furthermore, the dualism presented in the Affinity Argument has influenced Western philosophy for centuries. This influence extends to the mind-body dualism articulated later by René Descartes, the 17th-century founder of modern philosophy.
Once the Argument From Affinity has been presented, Simmias challenges Socrates by introducing a famous analogy that compares the soul–body relation to the harmony and strings of a lyre.
85c–86d
“[…] For, Socrates, when I examine what has been said, either alone or with Cebes, it does not seem quite satisfactory.”
[…]
“In this,” said he, “that one might use the same argument about harmony and a lyre with its strings. Once might say that the harmony is invisible and incorporeal, and very beautiful and divine in the well attuned lyre, but the lyre itself and its strings are bodies, and corporeal and composite and earthy and akin to that which is mortal. Now if someone shatters the lyre or cuts and breaks the strings, what if he should maintain by the same argument you employed, that the harmony could not have perished and must still exist? For there would be no possibility that the lyre and its strings, which are of mortal nature, still exist after the strings are broken, and the harmony, which is related and akin to the divine and the immortal, perish before that which is mortal. He would say that the harmony must still exist somewhere, and that the wood and the strings must rot away before anything could happen to it. And I fancy, Socrates, that it must have occurred to your own mind that we believe the soul to be something after this fashion; that our body is strung and held together by heat, cold, moisture, dryness, and the like, and the soul is a mixture and a harmony of these same elements, when they are well and properly mixed. Now if the soul is a harmony, it is clear that when the body is too much relaxed or is too tightly strung by diseases or other ills, the soul must of necessity perish, no matter how divine it is, like other harmonies in sounds and in all the works of artists, and the remains of each body will endure a long time until they are burnt or decayed. Now what shall we say to this argument, if anyone claims that the soul, being a mixture of the elements of the body, is the first to perish in what is called death?”
Simmias comes up with an intriguing analogy. He compares the soul-body relationship to the harmony produced by a well-tuned lyre. The harmony is beautiful and seemingly intangible, while the lyre and its strings are physical and subject to decay. Simmias argues that if the soul is like the harmony of a lyre, it cannot exist without the body, just as the harmony vanishes when the lyre is destroyed. This challenges the notion of the soul’s independent existence and immortality, suggesting that it might be inextricably linked to the physical body and perish along with it.
Socrates responds to Simmias’ objection (92a–94e) by presenting several key points to differentiate the soul from the attunement of an instrument. Firstly, Socrates argues that the soul—as they have already agreed following the previous arguments—exists before the body is formed, unlike the attunement of an instrument. Secondly, he highlights that there are degrees of attunement but no degrees of the soul. Thirdly, Socrates points out that if the analogy with attunement were correct, it would imply that no soul was better or worse than any other soul. This contradicts our understanding that an immoral soul is out of tune and in disharmony, whereas a virtuous soul is in tune and in harmony. Lastly, Socrates emphasizes that the soul is the master of the body, and this is unlike the relationship between an instrument and its attunement. These distinctions aim to illustrate the soul’s unique nature and refute Simmias’ analogy between the soul and the attunement of an instrument.
Cebes raises a counterpoint to Simmias’ objection, which in turn challenges Socrates.
86e–88b
“I do not agree with Simmias’ objection, that the soul is not stronger and more lasting than the body, for I think it is far superior in all such respects. […] It seems to me that it is much as if one should say about an old weaver who had died, that the man had not perished but was safe and sound somewhere, and should offer as a proof of this the fact that the cloak which the man had woven and used to wear was still whole and had not perished. Then if anyone did not believe him, he would ask which lasts longer, a man or a cloak that is in use and wear, and when the answer was given that a man lasts much longer, he would think it had been proved beyond a doubt that the man was safe, because that which was less lasting had not perished.
“But I do not think he is right, Simmias, and I ask you especially to notice what I say. Anyone can understand that a man who says this is talking nonsense. For the weaver in question wove and wore out many such cloaks and lasted longer than they, though they were many, but perished, I suppose, before the last one. Yet a man is not feebler or weaker than a cloak on that account at all. And I think the same figure would apply to the soul and the body and it would be quite appropriate to say in like manner about them, that the soul lasts a long time, but the body lasts a shorter time and is weaker. And, one might go on to say that each soul wears out many bodies, especially if the man lives many years. For if the body is constantly changing and being destroyed while the man still lives, and the soul is always weaving anew that which wears out, then when the soul perishes it must necessarily have on its last garment, and this only will survive it, and when the soul has perished, then the body will at once show its natural weakness and will quickly disappear in decay. And so we are not yet justified in feeling sure, on the strength of this argument, that our souls will still exist somewhere after we are dead. For if one were to grant even more to a man who uses your argument, Socrates, and allow not only that our souls existed before we were born, but also that there is nothing to prevent some of them from continuing to exist and from being born and dying again many times after we are dead, because the soul is naturally so strong that it can endure repeated births,—even allowing this, one might not grant that it does not suffer by its many births and does not finally perish altogether in one of its deaths.”
Cebes disagrees with Simmias’ analogy and proposes his own. He compares the soul to a weaver and the body to the cloaks the weaver creates. Just as a weaver outlives many cloaks, the soul might outlive many bodies. However, Cebes points out that this doesn’t necessarily mean the soul is immortal. The weaver eventually dies, and so might the soul, even if it endures longer than any single body. This analogy adds a new dimension to the debate, highlighting the possibility that the soul, while resilient, might not be eternally indestructible.
While Simmias’ objection was simple to discuss and answer, Socrates is well aware that Cebes’ is significantly more challenging. This prompts him to make a final argument that renegotiates the relationship between the opposites.
105b–107d:
“[…] now that I see another safe reply deduced from what has just been said. If you ask me what causes anything in which it is to be hot, I will not give you that safe but stupid answer and say that it is heat, but I can now give a more refined answer, that it is fire; and if you ask, what causes the body in which it is to be ill, I shall not say illness, but fever; and if you ask what causes a number in which it is to be odd, I shall not say oddness, but the number one, and so forth. Do you understand sufficiently what I mean?”
“Quite sufficiently,” he replied.
“Now answer,” said he. “What causes the body in which it is to be alive?”
“The soul,” he replied. “Is this always the case?”
“Yes,” said he, “of course.”
“Then if the soul takes possession of anything it always brings life to it?”
“Certainly,” he said.
“Is there anything that is the opposite of life?”
“Yes,” said he.
“What?”
“Death.”
“Now the soul, as we have agreed before, will never admit the opposite of that which it brings with it.”
“Decidedly not,” said Cebes.
[…]
“Well then what do we call that which does not admit death?”
“Deathless or immortal,” he said.
“And the soul does not admit death?”
“No.”
“Then the soul is immortal.”
[…]
“Necessarily,” he said. “And must not the same be said of that which is immortal? If the immortal is also imperishable, it is impossible for the soul to perish when death comes against it. For, as our argument has shown, it will not admit death and will not be dead, just as the number three, we said, will not be even, and the odd will not be even, and as fire, and the heat in the fire, will not be cold.”
In his first argument, the Argument from Opposites, Socrates posits that one opposite arises from its corresponding opposite in a perpetual cycle of generation and destruction. However, his Final Argument introduces a subtle shift in focus. He moves beyond a general discussion of opposites and emphasizes that certain things possess an essential characteristic that defines their nature. Fire, for example, is inherently hot; it cannot be cold without violating its essence.
Applying this principle to the soul, Socrates asserts that its defining characteristic is to enliven or bring life. Since death is the antithesis of life, the soul cannot experience death—just as fire cannot be cold. This intrinsic quality of the soul establishes its immortality. Furthermore, anything immortal is inherently indestructible. Thus, even when the body perishes, the immortal soul persists.
The Final Argument’s assertion of the soul’s immortality resonates with various theological and religious beliefs. The idea of a soul transcending the physical body and continuing after death is common in many spiritual practices. Christianity, Hinduism, and Buddhism, despite their differences, all embrace the concept of a transcendent aspect of human existence that persists beyond physical death. The Phaedo offers a philosophical perspective on this enduring human quest for meaning and transcendence, inviting contemplation on the connections between philosophical reasoning and spiritual beliefs.
Despite Socrates’ four arguments, his companions still doubt the soul’s immortality and life after death. To reassure them, he shares a comforting myth (107a-115a) that vividly depicts the afterlife, where souls are judged and assigned destinations based on their moral character during earthly life. Philosophical souls, embodying wisdom and virtue, ascend to a blissful realm where they live with the gods, while those corrupted by vice are condemned to Tartarus. Even souls that are not entirely virtuous can seek redemption through punishment and reincarnation. In narrating this myth, Plato’s Socrates reaffirms his belief in the immortality of the soul and implies that, since he has led a virtuous life, he has nothing to fear. His death will only be the beginning of another, happier life next to the gods.
117b–c:
[…]
without trembling or changing color or expression, but looking up at the man with wide open eyes, as was his custom, said: “What do you say about pouring a libation to some deity from this cup? May I, or not?”
“Socrates,” said he, “we prepare only as much as we think is enough.”
“I understand,” said Socrates; “but I may and must pray to the gods that my departure hence be a fortunate one; so I offer this prayer, and may it be granted.” With these words he raised the cup to his lips and very cheerfully and quietly drained it.
The Phaedo concludes with the poignant scene of Socrates’ death, where his serene acceptance exemplifies his philosophical beliefs. Rather than ending with abstract arguments, the dialogue culminates in a vivid demonstration of Socrates’ principles. This powerful conclusion emphasizes that, for Socrates, philosophy is not merely theoretical but a lived reality, allowing one to confront death with equanimity.
In Plato’s Phaedo, Socrates’ final hours spark a profound exploration of the soul’s immortality. Through philosophical debate and a captivating myth, the dialogue explores the nature of the soul and its potential afterlife, leaving a lasting impact on our understanding of life, death, and the human spirit.
For an overview of Plato’s arguments regarding the immortality of the soul in the Phaedo and a general idea of his philosophical views on the subject, check out this video:
To learn more about Plato’s perspective on the immortality of the soul, and how, based on its philosophical or non-philosophical previous life, a soul can experience happiness and rewards or sadness and punishments in the afterlife, keep on reading the Phaedo. For further information on the dialogue, check out this article on Plato’s Phaedo from the Internet Encyclopedia of Philosophy.
This work has been adapted from Plato, Phaedo, a title from Perseus Digital Library. This work is in the public domain. All images were created using Midjourney.
Giasoumi, Athanasia. 2025. “Exploring Immortality: Plato’s Phaedo.” The Philosophy Teaching Library. Edited by Robert Weston Siscoe, <https://philolibrary.crc.nd.edu/article/exploring-immortality>
Forms – The perfect, divine, and intelligible entities that exist independently of the physical world. They are comprehensible only through reason, not through our senses, and their existence explains the properties of objects in the physical world.
Recollection – The soul existed prior to birth; during this time it learned everything, and hence all learning is only recalling what we already know.
Immortality of the Soul – Unlike the body, the soul is not subject to physical death, because it is immortal and indestructible.
Philosophy – The practice of preparing the soul for death by training it to think and exist independently of the body
Death – Plato understands this as the soul’s separation from the body
Human Identity Across Time – Locke’s notion that any human stays the same across time if, and only if, it maintains the same (distinctively human) organizing structure of parts.
Substance Identity Across Time – Something is the same substance across a segment of time if, and only if, it continuously exists across the relevant segment of time without gaining or losing any of its parts.
Immaterial Soul – A personal thinking substance without any physical constitution.
Personal Identity Across Time – Whatever makes someone the numerically same person (i.e., that very person) at different times; according to Locke, it is a relation of first-person consciousness via memory.
Person – Locke’s forensic definition of person (pertaining to courts of law regarding the justice of praise, blame, reward, or punishment): a thinking, intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing in different times and places.
The Prophet Muhammad is a central figure in Islam. He is viewed as the last of a long line of prophets, which includes Moses and Jesus. He is responsible for writing the Quran, which was dedicated to him by the angel Gabriel. His life and sayings are recounted in the Hadith; he is viewed as an exemplary role model of Islamic life and faith.
Exhortation — The method of understanding and interpreting Truth available to the common people. The majority of people take scripture literally and understand truth and right action based upon this understanding. They are persuaded by the vivid imagery of the Quran and the rhetorical exhortations of religious leaders. Averroes takes this to be lowest form of understanding
Dogmatic Discourse — The method of understanding displayed by those who, through natural ability and habit, are able to have a deeper understanding of the Quran, and of the truths it illuminates. These people know that not all of the scriptures are to be taken literally, and that greater underlying Truths are revealed by interpreting some elements allegorically. Still, they err on the side of dogmatism and literal interpretation whenever uncertainty arises. Averroes associates this way of thinking with Muslim theologians and views this to be the middle level of understanding.
Philosophical Inference – The type of understanding associated with philosophical demonstration or argument. This is the highest level of understanding, accomplished by a select few, who have a natural capacity for philosophy and proper philosophical training.
Law — The Quran (the central religious text of Islam) and, to a lesser extent, the Hadith (reports of what the prophet Muhammad said and did). Averroes is concerned with explaining how philosophy relates to what Muslims take to be the unerring Truth regarding God and the nature of existence, as they are expressed in Scripture.
Occasionalism — a theory claiming that God is the only true cause of changes in the world. For example, when you high-five me, you’re not really the cause of the stinging sensation I experience. God is the cause. Your high five is just the occasion on which God causes it.
Interactionism — a theory claiming that things in the world can truly cause changes in each other. For example, when you high-five me, you truly cause me to experience a stinging sensation in my hand.
Substance Dualism — a theory claiming that the mind (or soul) and body are two distinct and very different things.
Body — what it sounds like! The body is the physical part or aspect of a thing and has characteristics like shape, size, etc.
Soul — that part or aspect of a thing involving mental aspects of their existence, e.g., thoughts, feelings, decisions, etc. The “soul”, in this sense, is more or less just the mind.
Causal Interaction — When one thing acts (i.e., itself does something) and in so acting makes another thing change. For example, when you high-five me, you cause me to experience a stinging sensation in my hand.
God as God – The phrase “God as God” is basically a synonym for “God the subject.” In other words, it refers to God precisely in God’s status as an incomprehensible divine Other.
Incarnation – The Christian doctrine of the incarnation is the notion that the word of God became fully human in the person of Jesus of Nazareth. It is closely associated with the doctrine of the trinity, which asserts that God the Father, God the Son (Jesus as the word made flesh), and God the Holy Spirit are one God.
Religious Fanaticism – In Feuerbach’s use of the term, a religious fanatic is someone who is unwaveringly faithful to God as an utterly mysterious superhuman being. They subordinate other things—especially the love of other humans—to submission before this divine other.
God the Subject – When Feuerbach refers to God as a subject, he is referring to the commonplace religious belief that God is a being who has various attributes, like a loving nature.
Faith Separates Man From God – Faith separates God from man in this sense: it treats God as a mysterious other, a being radically distinct from us.
Faith – Belief in and fidelity to a transcendent divine subject like God.
Orthodoxy – Orthodoxy refers to “right belief,” and it is concern with identifying heresies and ensuring that people believe and practice correctly.
Indirect Form of Self-Knowledge – Feuerbach’s view is that religious belief is a naive way of relating to our human nature and its perfections. It is naive or childlike because it treats these as external realities that belong to God. He believes a mature and contemplative person realizes these don’t belong to God, but rather to our species, abstractly conceived.
Above the Individual Man – The human perfections are “above the individual” insofar as no particular individual ever perfectly realizes them. They are abstractions.
Divine Trinity – Feuerbach is having fun here. He is using the theological phrasing of the Trinity to talk about human perfections. In calling reason, love, and freedom of the will “divine,” he means they are absolutely good; they are activities whose goodness is intrinsic to their practice or exercise. This isn’t a novel philosophical view. For example, Immanuel Kant argued that autonomy or a good will is the only thing which is unconditionally good.
Perfections – The end to which a faculty or power is ordered. For example, omniscience would be the perfection of the intellect. Traditionally, God is said to possess all perfections.
Love – When Feuerbach writes about love, he is referring to unconditional concern for others and the desire for fellowship with them. He is here asserting that love, understood in this sense, is the perfect activity of the affective faculty. In other words, our feelings and passions are fully actualized and engaged in an intrinsically valuable activity when we genuinely love others.
Infinite – The infinite is whatever can be understood as unbounded or unlimited. Human nature in the abstract is unbounded and unlimited. It is only bounded or limited in its concrete form as it is realized by particular material individuals.
Higher Consciousness – The sort of consciousness that mature human beings possess, but which other animals do not. It is “higher” than animal consciousness because it involves thinking abstractly about the form or essence of things.
Science – Feuerbach uses the term science in its classical sense, meaning systematically organized knowledge. Any body of knowledge founded on an understanding of first principles and the essences of things is a science in this sense.
Popular Sovereignty – The view that a government’s authority to rule comes from the people, making a ruler subject to the will of their citizens.
The Divine Right of Kings – The theory that kings are chosen by God and thus that political revolt is a rebellion against the will of God.
Synthesis – The prefix ‘syn-’ means “together,” so a synthesis “brings together” or combines elements of both a thesis and its antithesis.
Antithesis– An antithesis is the contradiction of a thesis. For example, internationalism could be understood as the antithesis of nationalism.
Thesis – In Hegelian terms, a thesis can be understood as a position or theory. Examples include any of the “-isms” that we discuss in science, history, and philosophy, such as Darwinism, capitalism, nationalism, etc.
Progressor’s Temptation – a unique temptation for those making progress in which pride impedes their further progress and leads to backsliding.
Progressors – those who are not yet expert Stoic practitioners, but who are also aware of the fact that they must change their lives in that direction. They are working on making progress.
Intellectualism – the philosophical view that our motivations and emotions are all judgments. The reason why you do something, your motivation, is because you believe it’s the right thing to do. The reason why you feel good or bad about something, an emotion, is because you believe that something good or bad happened to you.
Duties – acts of service, obedience, and respect that we owe to each other. The duties we owe to each other depend on what kind of relationship we have.
Askeses – exercises of Stoic thought and practice that make the lessons and habits of Stoic philosophy second-nature for Stoic practitioners.
Externals – things that are not under our control but that are all-too-easily confused with things that should be important to us, like wealth, status, and pleasure. Too many people believe externals like these are necessary for the good life, and the Stoic path is to focus not on these things but rather what is up to us.
The Fundamental Division – the division between things that are under our direct control and those that are not. The important lesson is to care only about the things we can control.
The Greatest Happiness Principle – A principle which says that actions are right insofar as they promote happiness and wrong insofar as they promote unhappiness
Higher and Lower Pleasures – Types of pleasures that differ in terms of their quality. Things like food and drugs create lower pleasures. Things like intellectual pursuits and doing the right thing create higher forms of pleasure.
The Doctrine of Swine – An objection that utilitarianism entails that if people would be happy rolling in mud, that’s what would be morally best for them to do, so we should reject the theory.
Utilitarianism – A normative theory of which actions are right or wrong. Utilitarianism says the right action is that which maximises utility.
Jeremy Bentham – Considered by some as the father of utilitarianism, Bentham was a moral philosopher and one of John Stuart Mill’s teachers
Epicurus – an ancient Greek philosopher and one of the first to advocate that the ultimate good is experiencing pleasure and avoiding pain.
Utility – The thing that is ultimately valuable in itself. For Mill, this is happiness, which he then understands as pleasure and the absence of pain.
Contract Theory – a modern political theory identifying consent as the sole justification for government. Contract theory is associated with Thomas Hobbes (1588-1679), John Locke (1632-1704), Jean Jacques Rousseau (1712-1778), and more recently, John Rawls (1921-2002)
Prejudice – a foundational, strongly held, unreasoned (but not necessarily irrational) moral opinion or belief. We might believe, for example, that parents have special obligations towards their own children.
A Priori – a philosophical term of art meaning (in Latin) “prior to experience,” which refers to knowledge that is innate or arrived at purely through reasoning, like the truths of mathematics.
Rights – moral claims invoking immunity from (or entitlement to) some specific treatment (or good) from others. Commonly recognized rights include the right to free speech or the right to healthcare.
Reform – a change in the social order that originates from the existing character of society. An example would be market-based healthcare reform in a capitalist society.
Conservatism – a modern political ideology that aims to preserve and promote the existing (or traditional) institutions of society. These institutions typically include the rule of law, property, the family, and religion.
Contingent Being – A being that can fail to exist. Its existence is not guaranteed. This being might come to exist or it might not.
Necessary Being – A being that can’t fail to exist. Its non-existence is impossible. This also means that such a being has always existed.
Want to read more about why the infinite regress option doesn’t work in the Second Way? Check out Sean Floyd’s entry in the Internet Encyclopedia of Philosophy.
Efficient Cause – An efficient cause is something that directly makes another thing exist or move. An example of this is when I kick a ball down a hill. I am the efficient cause of the ball rolling down the hill because I make it move down the hill.
Infinite Regress: Begin with some fact. We begin to explain that fact by appealing to another fact, where these facts are related by either causality or dependence. To create the regress, you keep appealing to more and more facts about causality and dependence without end.
Actuality – An ability or action something is currently exercising. Imagine that I am sitting comfortably at my desk, and then I stand up to take a break from reading. In this case, I am now actually standing.
Potentiality – What something has the capacity to do, but isn’t currently doing. Imagine I am sitting comfortably at my desk. Even though I’m not currently standing, I have the capacity to be standing. So, even while I’m not standing, I have the potential to stand.
Theists and Non-Theists – A theist is someone who believes that God exists, while a non-theist does not. Non-theists include atheists, who believe that God does not exist, and agnostics, who are uncertain about whether God exists.
Glaucon – one of Plato’s brothers and one of Socrates’ main interlocutors in the Republic dialogue. In that dialogue, he challenges Socrates to provide a compelling justification for why one should be a just person beyond merely following conventions or avoiding punishment. This sets up Socrates’ defense of justice as intrinsically worthwhile. Throughout the Republic, Glaucon prods Socrates to fully explain his theories of the ideal society, philosopher-kings, and the Form of the Good.
Aristotle – a Greek philosopher (384-322 BC) who studied under Plato and went on to be one of the most influential philosophers to ever live. Simply called “The Philosopher” by Thomas Aquinas and others in the medieval period, Aristotle’s views would eventually be synthesized with Christian theology, laying the intellectual foundation for later scholarly developments in Western Europe.
Understanding – Socrates describes education as turning one’s “understanding” in the right direction. The word “understanding” here translates the ancient Greek term “to phronēsai,” which means “understanding,” “being conscious,” or “having insight.” People who are wicked focus their “understanding” on how best to accomplish their selfish and narrow desires. Those who are wise, in contrast, have learned to focus their “understanding” on what is truly good and beneficial.
The Form of the Good – Socrates characterizes the ultimate goal of education as coming to know “the Form of the Good.” The Form of the Good is his technical term for the meaning of goodness: what it is to be good. Socrates is clear that this “knowledge of the Good” is not simply theoretical knowledge, but also knowledge in the sense of “knowing how”: knowing how to achieve what’s good, to do what’s good, to accomplish what’s good. Mere “book knowledge” or simply being smart is not enough.
The Intelligible – Socrates uses “the intelligible” to name the aspects of the world that we can only grasp through thinking or insight. With my eyes I can see the tree outside my window, but what it means to be a tree is something I can only comprehend in thought. Likewise, I can see the people around me, but human nature, human dignity, and what it means to be human is something I can only grasp conceptually. “The intelligible” is the world insofar as it “makes sense” and can be comprehended.
The Visible – By “the visible,” Socrates means those aspects of the world we can perceive with our five senses and our imagination—those aspects of the world we can see, hear, taste, smell, touch, and imagine. For example, with my eyes I can see the sky, trees, people around me, and so on as visible things. “The visible” is the world insofar as it can be perceived and imagined.
Education – Socrates says that the allegorical story he tells represents the effect of education on human nature. “Education” here is a translation of the ancient Greek word “paideia,” which means “education” in the widest sense of the term. “Paideia” doesn’t mean “education” in the sense of going to school or getting good grades. Instead, it refers to the process of becoming a wise, intelligent, good, and well-rounded human being.
Allegory – An allegory is a symbolic narrative where characters, events, and/or settings represent abstract ideas or convey deeper meanings beyond the literal story. Socrates tells such a symbolic narrative in the passages below. The characters, events, and setting of his narrative symbolize the effect of what he calls “education.”
Self-knowledge – Knowledge of the contents of one’s own mind, such as one’s own beliefs and desires. Self-knowledge can be gained through introspection, that is, by reflecting on what one thinks and experiences. Some philosophers believe that self-knowledge has special properties that our knowledge of the external world lacks, such as being clearer, more reliable, or more valuable.
Dualism – The view that the mind is entirely distinct from the body. This view is usually contrasted with different kinds of monism, which hold that the mind is ultimately just a part of the body (materialism) or that the body is ultimately just a part of the mind (idealism). Dualists hold that the mind and the body are fundamentally different aspects of reality, and both categories are needed to properly describe the universe, especially the human person.
The Self – What the ‘I’ in ‘I am, I exist’ refers to; the part of you that really makes you you. Many philosophers have provided rich accounts of what the self ultimately is, including the soul, the mind, one special feature of the mind (such as consciousness), a mixture of all these elements, or perhaps a mere illusion.
The ‘Cogito’ – Descartes’ famous claim ‘I think, therefore I am’ is often referred to as the cogito. The name comes from the Latin rendering of this phrase, which is ‘cogito, ergo sum.’ Descartes held that one can always believe this proposition with certainty. We cannot doubt our own existence, so the cogito survives his exercise of intense doubt. The cogito appears several times in Descartes’ writings, and he often phrased it slightly differently each time. It appears in the Second Meditation as ‘I am, I exist.’
Certainty – When one believes something with certainty, one is maximally confident that it is true. A certainty is something that is beyond dispute or immune to doubt. Although this captures the basic idea, like many epistemological notions, clarifying precisely what the notion of certainty amounts to is an ongoing area of philosophical research.
Vice – A bad habit that we learn over time through instruction or instinct and that we develop through repetition. What makes the habit bad is that, once we have that habit, our tendency is to do the incorrect thing in certain types of situations. We may choose to do something entirely uncalled for in that situation, or we may act at the wrong time, in the wrong way, to the wrong degree, or with the wrong attitudes, or for the wrong reasons.
Relative Mean – The “Goldilocks amount” of some type of action or emotion. When you act in this way, according to Aristotle, you act exactly as is required under the current circumstances. This means that you do what is called for by the situation at hand, rather than doing something too extreme or not doing something extreme enough. You do something in the moderate amount (the mean amount) relative to the specific situation you are in when you need to act.
Excellence/Virtue – A good habit that we learn over time through instruction and repetition. What makes the habit good is that, once we have that habit, we have a strong tendency to do the right thing at the right time, in the right way, to the right degree, with the right attitudes, whenever we are confronted with a situation that we know calls us to exercise that habit.
Doxastic Voluntarism – the view that we have at least some control over what we believe.
Evidence – information that increases the probability that a claim is true.
Sufficient – enough of something for a particular purpose. Whether something is sufficient is context-dependent.
Solon – In the Histories of Herodotus, Solon visits Croesus, the king of Lydia. Even though Croesus shows Solon all of his wealth, Solon refuses to call him the happiest man who ever lived because he does not know how Croesus will die
Priam – According to Greek mythology, Priam was the final king of Troy during the Trojan War. Despite his wealth and political power, he was killed by Achilles’ son Neopotolemus during the Sack of Troy
Virtue – The consistent and reliable tendency to perform one’s function excellently. When a person has a certain virtue, like courage, they have spent time developing the habit, in this case reacting to danger well, using their human abilities. The virtues then make it possible for us to live a life of flourishing
Sardanapalus – An Assyrian king described by the historian Diodorus as living a life of extreme decadence. Sardanapalus indulged himself with food, alcohol, and many concubines, even going so far to say that physical gratification is the purpose of life. Chrysippus said that, on his tomb is inscribed the following: “Though knowing full well that thou art but mortal, indulge thy desire, find joy in thy feasts. Dead, thou shalt have no delight […] I have only what I have eaten, what wantonness I have committed, what joys I received through passion; but my many rich possessions are now utterly dissolved.”
Function – the characteristic activity of a given thing which makes it what it is. The function of a knife is cutting, while the function of a heart is to pump blood
Eudaimonia – Frequently translated as ‘happiness’, eudaimonia means the attainment of active human flourishing, and is the end Aristotle identifies as humanity’s highest final good
Final Good – A good that we pursue for its own sake. Common examples of final goods include happiness, knowledge, and friendship
Instrumental Good – A good that we pursue for the sake of some other good. A common example is money, as money allows us to purchase other kinds of goods
Anytus – an Athenian politician, war general, and one of the primary accusers behind Socrates’ prosecution. Anytus feared that Socrates would undermine the young Athenian democracy he had helped create and defend
Oracle of Delphi – the high priestess at the temple at Delphi, the oracle was one of the most sought after seers of the ancient world and was thought to relay messages from the god Apollo
Chaerephon – an ancient Greek from the city Sphettus, Chaerephon is remembered as a loyal friend of Socrates, also making an appearance in two other Platonic dialogues, the Charmides and the Gorgias
Meletus – A poet and citizen of Athens and one of Socrates’ accusers. Amongst other things, Meletus accused Socrates of corrupting the youth
Apollo – the ancient sacred site Delphi was dedicated to the god Apollo, an ancient Greek god and the god that Socrates refers to throughout the Apology
Virtue – a character trait, acquired through habitual practice, that enables one to act well. The virtues can also be thought of as excellences of human character, as they make it possible for us to live a life of flourishing. Examples of the virtues include courage, prudence, and justice
The Evil Demon Argument – Argues that we cannot hold any of our beliefs with certainty because we could be radically deceived by an evil demon. A classic argument given by Descartes for doubting the reliability of almost all of our beliefs
Philosophical Skepticism – The position that we do not know many things that we ordinarily take ourselves to know
A Posteriori Knowledge – Knowledge that can only be acquired through having particular, concrete experiences. Such knowledge can be gained simply through our everyday experiences, or through more complex means like controlled scientific experiments
A Priori Knowledge – Knowledge that can be gained without having any particular concrete experiences. Such knowledge is typically gained by rational insight or intuition
Cartesian Method of Doubt – A process employed by René Descartes of rejecting all beliefs that he had at least some reason to doubt in order to see if he had any beliefs that he could know with certainty
Revelation – Theological truths that have been made known by means of some religious text, testimony, authority, or experience, or the act or process in which such truths are made known.
Rationalism – The view that the only reliable means of coming to know truths about God is reason. As a result, what we might otherwise believe by means of faith ought to be disregarded or even rejected in favor of what we must believe by means of reason.
Fideism – The view that the only reliable means of coming to know truths about God is faith. As a result, what we might otherwise believe by means of reason ought to be disregarded or even rejected in favor of what we must believe by means of faith.
Faith – The act of accepting a proposition as true for which there is less than demonstrable evidence, which rises above mere opinion but falls short of logical or scientific demonstration. Faith can also refer to a particular religious tradition or the body of beliefs that are central to that religious tradition.
Virtue – a character trait, acquired through habitual practice, that enables one to act well. The virtues can also be thought of as excellences of human character, as they make it possible for us to live a life of flourishing. Examples of the virtues include courage, prudence, and justice
Socratic Ignorance – an awareness of one’s own ignorance, and the reason that Socrates was deemed wise by the Oracle of Delphi. A person who lacks Socratic Ignorance may believe they know many things they actually don’t, leading them to overestimate how well they understand the world
Apology – a formal defense of justification of an action or belief. A Christian apologist, for example, is someone who defends their faith and seeks to justify it through an appeal to reason.
