Plato’s student, Aristotle, famously wrote that philosophy begins in wonder. As children we begin asking ‘why, why, why’ about everything. We are satisfied with no answers, and always want to plunge deeper and deeper, getting more and more fundamental explanations. At some point, most of us stop doing that quite so often. We still ask ‘why’ of many things, but we are satisfied more quickly than we were when we were children. In this section of the Republic, Plato presents a daring vision of philosophy. It has the job of answering the child’s question – it has the job of following that ‘why’ question as far as it can go. Plato wants us to fearlessly ask ‘why’ like the child, but to answer with the rigor and precision of the mathematician. Here, we’ll consider two central allegories he offers to help us understand that project and to see why we should still care about it as much as we once did.
Plato (428/427 or 424/423 – 348 BC) was an Athenian who, along with his one-time teacher Socrates, is widely considered to be the father of philosophy as we know it. ‘Plato’ is a romanization of what was actually probably a nickname, the Greek word ‘πλατύς,’ which can be translated as the English word ‘broad’. Most of Plato’s works that survive are in the form of a dialogue. This means that instead of the more familiar kind of philosophical writing, there are multiple characters who hold different viewpoints having a conversation. Plato typically uses real people who would have been familiar to Athenians as the characters in his dialogues, although in most cases it is unlikely that such conversations ever really occurred. In most dialogues, it seems pretty clear that Plato treats the character he calls ‘Socrates’ as a mouthpiece for his views, but it is hard to be sure since Plato never tells us explicitly. In the sections of the Republic which you are about to read, we will think of Socrates as offering Plato’s own views.
The Republic is certainly one of Plato’s greatest works. It is a sprawling dialogue that attempts to describe the ideal state. In doing so, Plato addresses many fundamental questions about the good life, the nature of reality, and how we come to know about it. The current section comes after the ideal city has mostly been set up, and with an account of the virtues already on the table. For those who want to dive in further, here is the full text.
Form (εἶδος / ἰδέα) – Intelligible, immaterial, perfect entities that explain the unity among the many things which share the feature named by the entity (e.g., Beauty, Squareness, Oddness). For example, think of a square. There might be many different squares, but they all share features like having four sides of equal length. So, the Form of Squareness would include all of those features that make something a square.
Guardian – This is the name Plato gives to the ruling class in his ideal city. Think of them as philosopher kings – they have complete control over the organization of the state. The Republic is partially about why Plato thinks they would be needed for an ideal system of government and what they would need to learn to do the job well.
Soul (ψῡχή) – What Greeks meant by this word is controversial. For now, think of it as the thing that makes you different from a rock or other objects, the thinking and experiencing part of you as well as the part of you that acts and makes decision. You might use the word ‘mind’ or ‘self’ to talk about this.
Virtue – Virtues are the character traits that make a person good. For example, most people consider courage and generosity to be virtues. English-speakers usually reserve the word ‘virtue’ for human beings, but in ancient Greek the word can be more comfortably applied to other beings as well.
We open dramatically. Plato is in the process of having Socrates give an account of what the rulers of the ideal city will have to be like. He has already concluded that they must have a wide range of knowledge necessary for ruling. Along with this knowledge, their commitment to virtue and the good of their fellow citizens is to be tested by a variety of strenuous tasks. I have inserted dialogue markers – S is Socrates and I is his interlocutor/discussion partner.
S: Then the aspirant must not only be tested in those labors and dangers and pleasures which we mentioned before, but there is another kind of probation which we did not mention—he must be exercised also in many kinds of knowledge, to see whether the soul will be able to endure the highest of all, or will faint under them, as in any other studies and exercises.
I: Yes, he said, you are quite right in testing him. But what do you mean by the highest of all knowledge?
S: You may remember, I said, that we divided the soul into three parts; and distinguished the several natures of justice, temperance, courage, and wisdom?
I: Indeed, he said, if I had forgotten, I should not deserve to hear more.
S: And do you remember the word of caution which preceded the discussion of them?
I: To what do you refer?
S: We were saying, if I am not mistaken, that he who wanted to see them in their perfect beauty must take a longer and more circuitous way, at the end of which they would appear; but that we could add on a popular exposition of them on a level with the discussion which had preceded. And you replied that such an exposition would be enough for you, and so the enquiry was continued in what to me seemed to be a very inaccurate manner; whether you were satisfied or not, it is for you to say.
I: Yes, he said, I thought and the others thought that you gave us a fair measure of truth.
S: But, my friend, I said, a measure of such things which in any degree falls short of the whole truth is not fair measure; for nothing imperfect is the measure of anything, although persons are too apt to be contented and think that they need search no further.
I: Not an uncommon case when people are indolent.
S: Yes, I said; and there cannot be any worse fault in a guardian of the State and of the laws.
I: True.
S: The guardian then, I said, must be required to take the longer circuit, and toil at learning as well as at gymnastics, or he will never reach the highest knowledge of all which, as we were just now saying, is his proper calling.
I: What, he said, is there a knowledge still higher than this – higher than justice and the other virtues?
S: Yes, I said, there is. And of the virtues too we must behold not the outline merely, as at present – nothing short of the most finished picture should satisfy us. When little things are elaborated with an infinity of pains, in order that they may appear in their full beauty and utmost clearness, how ridiculous that we should not think the highest truths worthy of attaining the highest accuracy!
I: A right noble thought; but do you suppose that we shall refrain from asking you what is this highest knowledge?
S: Nay, I said, ask if you will; but I am certain that you have heard the answer many times, and now you either do not understand me or, as I rather think, you are disposed to be troublesome; for you have of been told that the idea of good is the highest knowledge, and that all other things become useful and advantageous only by their use of this […]
Here we get a vital part of the Platonic understanding of philosophy. A complete account of something is systematic and precise. His problem with the earlier account given is not that it was false, per se, but that it was not carried out with the highest level of precision and rigor. Understanding the systematic nature of knowledge will help us see the importance of the coming allegories.
Imagine that you had to organize a society from scratch. You get a batch of babies who are one day going to be in charge – they are going to decide what the society should prioritize, how the rest of the society should be organized, and make all the major decisions. Now you have to decide how these babies are educated. What would you prioritize in their education? They can have advisors who inform them about specialized knowledge when it is relevant (like how much weight a certain bridge can take), but they have to be the ones who make the decisions. If you want them to consult such experts, that will have to be something you take into consideration in the way you educate them. How would you raise them?
Socrates, who is usually quite the talker, has some surprising news for us. His interlocutor asks him to tell them all about this wonderful Form of the Good. Socrates reminds his interlocutors about the previous point regarding systematicity. He will not simply say what he thinks, and he will certainly not do so in the incomplete manner that may have been suited to a previous point in their conversation. Notice how this should inform what he does say.
S: Well, but has any one a right to say positively what he does not know?
I: Not, he said, with the assurance of positive certainty; he has no right to do that: but he may say what he thinks, as a matter of opinion.
S: And do you not know, I said, that all mere opinions are bad, and the best of them blind? You would not deny that those who have any true notion without intelligence are only like blind men who feel their way along the road? […]
No, sweet sirs, let us not at present ask what is the actual nature of the good, for to reach what is now in my thoughts would be an effort too great for me. But of the child of the good who is likest him, I would fain speak […]
[T]here is an absolute beauty and an absolute good, and of other things to which the term ‘many’ is applied there is an absolute; for they may be brought under a single idea, which is called the essence of each.
I: Very true.
S: The many, as we say, are seen but not known, and the ideas are known but not seen.
I: Exactly.
Socrates is going to explain, by way of allegory, the role that the Form of the Good is going to play in the ideal systematic philosophy. He is telling you the role it plays in the whole system of reality. Understanding this will naturally put some constraints on what the Form of the Good can be, but we will save those speculations for after you understand the allegories.
Here we have an allusion to Plato’s doctrine of the Forms. We call many things beautiful. However, the many beautiful things do not share their particular kind of beauty. For example, the lighting in Caravaggio’s The Calling of St. Matthew is part of what makes it a beautiful painting. However, the same cannot be said for a beautiful person. Even another painting cannot have that lighting. So, whatever makes them all beautiful transcends their unique way of being beautiful. Of course, what they all share is beauty! But the shared beauty is something beyond all of them which is immaterial and perfectly beautiful. Plato calls the immaterial, shared thing a Form – and in this case, the Form of Beauty.
These Forms, as Plato points out in the passage, are invisible and intelligible. To understand what he means by this, simply notice that you never see beauty itself – instead, you see many beautiful things. On the other hand, you never understand the many beautiful things, because in endeavoring to understand their beauty, you understand the thing which they all share. What they all share, however, is participation in the Form of Beauty. So, when you try to understand what you see, your mind ascends to the Forms. This establishes a division between two parts of reality – the intelligible and invisible is separated from the visible and unintelligible. This is the distinction to which Socrates is referring. With that understood, we can now proceed to Socrates’ first allegory.
The allegory of the sun is about Plato’s view of the relationship between the Form of the Good and the ordinary objects we see all the time. Remember that he thinks all forms have a special relationship to the ordinary objects, but that the Form of the Good has an even more foundational role which he is using this allegory to explain.
S: And what is the organ with which we see the visible things?
I: The sight, he said.
S: And with the hearing, I said, we hear, and with the other senses perceive the other objects of sense?
I: True.
S: But have you remarked that sight is by far the most costly and complex piece of workmanship which the artificer of the senses ever contrived?
I: No, I never have, he said.
S: Then reflect; has the ear or voice need of any third or additional nature in order that the one may be able to hear and the other to be heard?
I: Nothing of the sort.
S: No, indeed, I replied; and the same is true of most, if not all, the other senses –you would not say that any of them requires such an addition?
I: Certainly not.
S: But you see that without the addition of some other nature there is no seeing or being seen?
I: How do you mean?
S: Sight being, as I conceive, in the eyes, and he who has eyes wanting to see; colour being also present in them, still unless there be a third nature specially adapted to the purpose, the owner of the eyes will see nothing and the colours will be invisible.
I: Of what nature are you speaking?
S: Of that which you term light, I replied.
I: True, he said.
S: Noble, then, is the bond which links together sight and visibility, and great beyond other bonds by no small difference of nature; for light is their bond, and light is no ignoble thing?
I: Nay, he said, the reverse of ignoble.
S: And which, I said, of the gods in heaven would you say was the lord of this element? Whose is that light which makes the eye to see perfectly and the visible to appear?
I: You mean the sun, as you and all mankind say.
S: May not the relation of sight to this deity be described as follows?
I: How?
S: Neither sight nor the eye in which sight resides is the sun?
I: No.
S: Yet of all the organs of sense the eye is the most like the sun?
I: By far the most like.
S: And the power which the eye possesses is a sort of effluence which is dispensed from the sun?
I: Exactly.
S: Then the sun is not sight, but the author of sight who is recognised by sight.
I: True, he said.
S: And this is he whom I call the child of the good, whom the good begat in his own likeness, to be in the visible world, in relation to sight and the things of sight, what the good is in the intellectual world in relation to mind and the things of mind.
I: Will you be a little more explicit? he said.
S: Why, you know, I said, that the eyes, when a person directs them towards objects on which the light of day is no longer shining, but the moon and stars only, see dimly, and are nearly blind; they seem to have no clearness of vision in them?
I: Very true.
S: But when they are directed towards objects on which the sun shines, they see clearly and there is sight in them?
I: Certainly.
S: And the soul is like the eye: when resting upon that on which truth and being shine, the soul perceives and understands and is radiant with intelligence; but when turned towards the twilight of becoming and perishing, then she has opinion only, and goes blinking about, and is first of one opinion and then of another, and seems to have no intelligence?
I: Just so.
S: Now, that which imparts truth to the known and the power of knowing to the knower is what I would have you term the idea of good, and this you will deem to be the cause of science, and of truth in so far as the latter becomes the subject of knowledge; beautiful too, as are both truth and knowledge, you will be right in esteeming this other nature as more beautiful than either; and, as in the previous instance, light and sight may be truly said to be like the sun, and yet not to be the sun, so in this other sphere, science and truth may be deemed to be like the good, but not the good; the good has a place of honour yet higher.
I: What a wonder of beauty that must be, he said, which is the author of science and truth, and yet surpasses them in beauty […]
The important point here is that for us to see something, we need something beyond our eyes functioning and the object being present before them. We need the constant presence of light – of a medium which enables vision. The sun is the relevant causal origin of light in ordinary circumstances, so the sun is a being by whose effects we are enabled at each moment to come to know things by vision, and without which at any moment we will cease to be able to know. Moreover, the sun is itself a potential object of vision.
We can apply this to forms in general as follows. Remember that the forms are the intelligible features of ordinary objects, which they all share. Think of a square for example. The features which make something a square are the same things you would name if I asked you why you thought it was a square, or what sort of things you noticed about it that led you to think it was a square. You would name its four sides, its 90 degree angles, etc. Without those things, you would never come to know the square at all! In this way, we can say that the forms make the particular objects knowable, like the way in which the light of the sun enables us to see objects. So, Plato is claiming that the Form of the Good is playing a similar role with everything. It makes everything intelligible. It is something shared by the four sides and the 90 degree angles, and shared by everything we can understand about any object. Just like your eyes make use of light in order to see, your mind makes use of the Form of the Good in order to understand. Just like the sun is visible, Plato also thinks the forms themselves are knowable.
Socrates has just said that knowledge and beauty are brought under the Good. Because they are both, presumably, good, they must participate in the Form of the Good. Indeed, they owe all their good features to the Form of the Good. The Form of the Good enables us to come to know things by giving them their status as intelligible beings and us our capacity to understand them with our mind.
S: You would say, would you not, that the sun is [not] only the author of visibility in all visible things, but of generation and nourishment and growth, though he himself is not generation?
I: Certainly.
S: In like manner the good may be said to be not only the author of knowledge to all things known, but of their being and essence, and yet the good is not essence, but far exceeds essence in dignity and power.
Socrates now draws our attention to another feature of the sun. It is responsible, not only for helping us see, but for the existence of the things we see. Imagine looking at a tree – neither you nor the tree would exist if there were no sun. Consequently, the sun both plays a role in how we learn and why we exist. So, it sustains the act of seeing in a very complex way. It enables you to come to see with its light, and it also enables you to come to see by enabling your and the tree’s existence. Likewise, the Form of the Good enables your very being along with enabling your capacity to know the intelligible things.
Here are two interpretations of what is going on.
First, think of goodness as existence or being itself. Existing makes it possible for us to know. It is through our nature (our being) that we can know things. Moreover, we can only know about other things because they exist. And because we are human, we are participating in the perfect Form of Humanity, which is itself also good. So goodness and being can be brought together, because by having a human nature we both participate in the Form of Being and the Form of the Good.
Alternatively, we could be more mystical. The good really is beyond being in some way. It is, in other words, more real than being. It transcends reality to such an extent that it is right to think of it as in itself un-knowable, at least to humans. At the very least, it could not be described. It is what holds together all of knowledge, goodness, and existence without thereby being a part of it. The good is beyond it all, and is nonetheless that which they all participate in. Do not be concerned if you had a hard time understanding this option, since that is, in a way, the point. This would explain why Socrates will not say what he thinks the good is. To attempt to define it would be to drag it down from its proper heights.
Both of these interpretations have won converts and influenced the philosophical tradition. With this understood, we can proceed to the allegory of the line.
Now Plato gives the second allegory, building on the first. He will be describing a line made up of different parts. Each part will correspond to a part of reality. He focuses at first on the relationship that particular objects have to the forms. So think of the relationship between the Form of a Knife, for example, and a particular knife that you are looking at. “The intelligible” refers to the forms, which we can understand, and “the visible” refers to the particular things, which we can see.
S: You have to imagine, then, that there are two ruling powers, and that one of them is set over the intellectual world, the other over the visible […] May I suppose that you have this distinction of the visible and intelligible fixed in your mind?
I: I have.
S: Now take a line which has been cut into two unequal parts, and divide each of them again in the same proportion, and suppose the two main divisions to answer, one to the visible and the other to the intelligible, and then compare the subdivisions in respect of their clearness and want of clearness, and you will find that the first section in the sphere of the visible consists of images. And by images I mean, in the first place, shadows, and in the second place, reflections in water and in solid, smooth and polished bodies and the like: Do you understand?
I: Yes, I understand.
S: Imagine, now, the other section, of which this is only the resemblance, to include the animals which we see, and everything that grows or is made.
I: Very good.
S: Would you not admit that both the sections of this division have different degrees of truth, and that the copy is to the original as the sphere of opinion is to the sphere of knowledge?
A reflection of something is caused by the thing it is a reflection of. There can be nothing in the reflection of your hand which is not from your actual hand. Otherwise, it would not be a reflection of your hand, but of something else. A reflection is truer if it captures something of the hand accurately (e.g., a blurry reflection would be less true than a clear one). Nevertheless, a reflection will always fall far short of accurately representing your hand (it cannot grab things, it has no other side, etc.).
So, Plato has just told us about the division of the visible part of the line. The lowest down are the images and reflections, and the next rung up are the original objects and beings that those images are images of. Now Plato moves above that, out of the visible and into the intellectual part of the line.
S: Next proceed to consider the manner in which the sphere of the intellectual is to be divided.
I: In what manner?
S: Thus: – There are two subdivisions, in the lower of which the soul uses the figures given by the former division as images; the enquiry can only be hypothetical, and instead of going upwards to a principle descends to the other end; in the higher of the two, the soul passes out of hypotheses, and goes up to a principle which is above hypotheses, making no use of images as in the former case, but proceeding only in and through the ideas themselves.
I: I do not quite understand your meaning, he said.
S: Then I will try again; you will understand me better when I have made some preliminary remarks. You are aware that students of geometry, arithmetic, and the kindred sciences assume the odd and the even and the figures and three kinds of angles and the like in their several branches of science; these are their hypotheses, which they and everybody are supposed to know, and therefore they do not deign to give any account of them either to themselves or others; but they begin with them, and go on until they arrive at last, and in a consistent manner, at their conclusion?
Plato’s point here is that some sciences take certain rules or principles for granted and then see where they can get from there. For example, consider the Peano axioms, which are a set of rules that we can derive the rest of arithmetic from. Those axioms are used to justify a particular arithmetical truth (e.g., 1 + 1 = 2). Those axioms themselves, however, are not defended by arithmetic. That is a narrow example but the point generalizes. If there is anything that a scientific endeavor takes for granted and does not attempt to justify, that is one of the “hypotheses” Plato describes above. This is so even if those hypotheses are as general as the view that the world is ordered by natural laws, or that physical stuff exists, or that our perceptions correspond to reality, and so on. In other words, it characterizes every science except the one Socrates is describing.
Plato likes those scientific enterprises, but he wants something new which can justify what those sciences take for granted. Can we defend these assumptions that inform the basic axioms of the sciences?
S: And do you not know also that although they make use of the visible forms and reason about them, they are thinking not of these, but of the ideals which they resemble; not of the figures which they draw, but of the absolute square and the absolute diameter, and so on –the forms which they draw or make, and which have shadows and reflections in water of their own, are converted by them into images, but they are really seeking to behold the things themselves, which can only be seen with the eye of the mind. […]
And of this kind I spoke as the intelligible, although in the search after it the soul is compelled to use hypotheses; not ascending to a first principle, because she is unable to rise above the region of hypothesis, but employing the objects of which the shadows below are resemblances in their turn as images, they having in relation to the shadows and reflections of them a greater distinctness, and therefore a higher value.
I: I understand, he said, that you are speaking of the province of geometry and the sister arts.
S: And when I speak of the other division of the intelligible, you will understand me to speak of that other sort of knowledge which reason herself attains by the power of dialectic, using the hypotheses not as first principles, but only as hypotheses –that is to say, as steps and points of departure into a world which is above hypotheses, in order that she may soar beyond them to the first principle of the whole; and clinging to this and then to that which depends on this, by successive steps she descends again without the aid of any sensible object, from ideas, through ideas, and in ideas she ends.
Instead of taking them for granted, Plato is talking about a project that would work to justify all of these hypotheses. It would be an attempt to demonstrate that all of the assumptions of science are true and explain why they are true. He thinks that until we have done this, since the axioms are taken for granted, they and their results are all likewise unjustified in the same way. Just like the sciences justify particular claims (e.g., this atom bomb will give off a blast as strong as 15 kilotons of TNT) by general principles, Plato wants to justify these general principles by even more fundamental principles. He thinks that we should embark on a project that seeks to systematize and thereby justify all the branches of human knowledge by going through this procedure of justification, without using any visible images, until we come to an indubitable first principle. That principle is, of course, the Form of the Good.
Here we have our final result, with all of its subsections and relations made clear. Lowest down we have the images, which are things like reflections in water and shadows. They are completely dependent on other objects for whatever reality they have. Then we have the original object, one more rung up the line and still in the visible realm. These are things like deer, trees, or rocks. Now we go from the visible into the intelligible, and start focusing on intellectual projects rather than on individual objects. The hypothetical sciences occupy the lower part of the line, and they use presupposed hypotheses to draw conclusions about the physical world. Finally we have dialectic, which is Plato’s proposed science that starts from the hypotheses and goes upward, seeking a firm starting place to defend and justify the truth of those hypotheses.
Plato wants us to comprehend the entirety of reality in a rigorous, systematic way. In one way, the entirety of the rest of the history of philosophy are various attempts to answer this challenge. What is the complete and rigorous system of knowledge that includes, justifies, and connects everything which we know? Major thinkers have either sought to answer the challenge as presented, to reframe the question, or to reject it. You are now equipped to understand the methodology that set the agenda for the majority of the course of Western philosophy and theology.
For one week, keep a journal about all of the major activities you do throughout the day. Then, think about each one and what is good about doing or succeeding at it. For example, if you attend a lecture at school, ask yourself what is supposed to be good about doing that. Then, don’t just stop at the first answer you come up with (for example, to get a good grade). Ask yourself further what is supposed to be good about that, why you do it, what role it plays in your life (for example, get a good grade -> keep my GPA high -> graduate with honors -> get a job that I enjoy and that pays well -> etc.). Keep going as far as you can. Likely, you will come to answers that seem final to you. When you’ve done this for a variety of activities, gather together the final answers you can give. Those will give you a sense of what you are treating as the good of your life, and you can see whether they seem like fitting candidates for such an important role.
For a more complete understanding of Plato’s view of reality and the ideal political state, you should read the rest of the Republic. You can also read a detailed overview of the Republic through the Internet Encyclopedia of Philosophy. The entire dialogue is a philosophical masterpiece, and will help you develop a better understanding of the arguments that Plato uses for some of his views which we have simply had to take for granted in this short article.
This work has been adapted from Republic, a title from the Internet Classics Archive. This work is in the public domain. All images were created using Midjourney.
Odermatt, Zachary. 2025. “More Beautiful Than the Truth: The Divided Line in Plato’s Republic, Book VI.” The Philosophy Teaching Library. Edited by Robert Weston Siscoe, <https://philolibrary.crc.nd.edu/article/the-divided-line>
Unconditioned: an ultimate explanation of reality. For example, if I explain why it is raining today by appealing to some atmospheric conditions, I can always ask for the cause of those conditions, and so on. Only a cause that is not caused by anything else (something unconditioned) would give us an ultimate explanation.
Transcendental Idealism: Kant’s mature philosophical position. It holds that appearances are not things in themselves, but representations of our mind. It is opposed to transcendental realism, which identifies appearances with things in themselves.
Appearances (vs. things in themselves): things as they are experienced by us (also known as phenomena). They should be distinguished from things as they are independently of our experience (things in themselves or noumena).
Metaphysics: the study of what there is. Traditionally, metaphysics is divided into general metaphysics and special metaphysics. The former investigates the general features of reality and asks questions such as ‘What is possible?’. The latter studies particular kinds of being and asks questions such as ‘Does God exist?’ or ‘Is the soul immortal?’.
Reason: the faculty that knows a priori. Kant uses this term in a general sense (the knowing faculty as such) and in a specific sense (the faculty that demands ultimate explanations).
A priori: term denoting propositions that can be known independently from experience. For example, propositions such as ‘All bachelors are unmarried’ or ‘The whole is greater than its parts’ can be known without recourse to any experience.
Make sure not to think that ‘unjustified’ means ‘false.’ Even if they are true, the point is just that this would not be something that had been shown.
‘Absolute’ might be a confusing word, here. Socrates means that the geometers are not reasoning about their drawing of the square, for example, but of the square itself. They do not conclude that, for the square they drew, the area is equal to the square of a side – they conclude that this is true for squares as an intelligible object, or, as Plato would say, the Form of the square.
By ‘science’, Plato means to be talking about all rational disciplines, including mathematics.
The form of the beautiful has to be perfectly beautiful because all instances of beautiful things are explained by it, so it has to be responsible for the highest possible degrees of beauty possessed by anything. Moreover, it has no trace of ugliness in it.
The form of the beautiful has to be immaterial because all the many beautiful things do not share any material – that is, they are all made of different stuff.
Form (εἶδος / ἰδέα) – Intelligible, immaterial, perfect entities that explain the unity among the many things which share the feature named by the entity (e.g., Beauty, Squareness, Oddness). For example, think of a square. There might be many different squares, but they all share features like having four sides of equal length. So, the Form of Squareness would include all of those features that make something a square.
Guardian – This is the name Plato gives to the ruling class in his ideal city. Think of them as philosopher kings – they have complete control over the organization of the state. The Republic is partially about why Plato thinks they would be needed for an ideal system of government and what they would need to learn to do the job well.
Plato has previously argued that we are made up of different parts. The first part is the appetitive which is responsible for our desires for food, sex, and other bodily needs. Then there is the spirited part, which longs for fame and honor. Finally, he identifies the rational part, which discerns what is good and bad for us through reason. The parts can all come into conflict with one another, and managing their relations is what Plato thinks justice is all about.
Soul (ψῡχή) – What Greeks meant by this word is controversial. For now, think of it as the thing that makes you different from a rock or other objects, the thinking and experiencing part of you as well as the part of you that acts and makes decision. You might use the word ‘mind’ or ‘self’ to talk about this.
Virtue – Virtues are the character traits that make a person good. For example, most people consider courage and generosity to be virtues. English-speakers usually reserve the word ‘virtue’ for human beings, but in ancient Greek the word can be more comfortably applied to other beings as well.
Was it his burly physique, his wide breadth of wisdom, or his remarkable forehead which earned him this nickname?
Aporia – A Greek term for “being at a loss” or “clueless.” Socrates often questions people until they have no idea how to define something that they thought they understood.
You might be confused by the word ‘attention’ below. In Greek the word is therapeia, from which we get the English word ‘therapy.’ It primarily means the same as ‘service’ as in ‘to serve,’ but shades into ‘worship,’ ‘take care of,’ and ‘attend to.’
Meletus – A poet and citizen of Athens and one of Socrates’ accusers. Amongst other things, Meletus accused Socrates of impiety and corrupting the youth.
Divine Voluntarism – The idea that God is free to determine even the most basic truths. If divine voluntarism is true, then God could have made it so that 2+2=5 or so that cruelty and blasphemy are holy and good.
Euthyphro Dilemma – The question, “Is a thing holy because the gods love it, or do the gods love it because it is holy?” The general idea of a forced choice (or “dilemma”) about the true order of explanation occurs often in philosophy and gets referred to by this term.
Essence – What a thing fundamentally is. A square might be red or blue without changing the fact that it’s a square, but a square must have four sides, so having four sides is part of a square’s essence.
Definition – The perfect description of a thing. A definition should pick out all and only examples of a thing. For example, ‘bachelor’ might be defined as ‘unmarried man,’ because all unmarried men are bachelors, and only unmarried men are bachelors.
In Disney’s retelling of the Hunchback of Notre Dame, the clergyman Claude Frollo orders the death of many Roma on religious grounds. It is clear, however, that he is really motivated by spite and his unrequited lust for the Romani woman Esmerelda.
Spanish conquistadors were shocked by the scope of ritual human sacrifice among the Aztecs, as hundreds or even thousands of people were sacrificed each year. The Aztecs thought that the sacrifices could repay the sacrifices the gods had made in creating the sun and earth.
Zeus – The god of sky and thunder in ancient Greek mythology, Zeus was depicted as chief among the gods and called the father of the gods and men.
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.
