Plato’s Philosophy: A Guide to Key Concepts
Affections
The four cognitive activities of the soul. The lower two are conjecture and belief, which lead to opinion, as they are the fruit of knowledge of sentient beings. The other two (intelligence and discursive thought) lead to truth (science), as they are the result of knowing intelligible beings.
Soul
What essentially defines man. Its nature is to live separated from the body. It has a tripartite structure: the rational soul (immortal), the faculty of rational knowing; the irascible soul, character or mental strength; and the concupiscible soul, the ability to desire and experience passions. The rational part is intelligible and therefore higher than and independent of the body, which becomes its prison. Therefore, the union of soul and body is accidental and temporary (anthropological dualism).
Allegory
A literary figure used to express a thought through images, creating a correspondence between the image and the idea represented. For example, in the allegory of the sun, the image of the sun shining over objects represents the idea of the Good doing good to other things that exist thanks to its influence.
Arts
The various branches that make up mathematics. The text cites two: geometry and arithmetic. These are the result of the discursive thought of reason. In general, Plato meant by art that which is made pursuant to a method or set of rules. Mathematics has its method and is therefore an art.
Good
With a capital ‘G’, this refers to the Idea of Good. With a lowercase ‘g’ and/or plural, it refers to actions or good sentient beings. It also appears in lowercase when referring to the good in general, without referring to its definition as a Platonic Idea. It is a subsisting and supreme Form, the sun that illuminates all of reality and the summit of the World of Ideas. It is the absolute Idea, the Idea of Ideas, so elevated and wonderful that it is beyond Being, so that things are only good insofar as they partake in the only absolute Good.
Science
True knowledge (universal, necessary, and unchangeable). It is only known because it is obtained through proper knowledge of intelligible beings, the only true beings. It may be knowledge of mathematical objects by reasoning (mathematics) or knowledge of Ideas through intelligence (dialectic science).
Dialectic Science
Results from direct (intuitive) knowledge of Ideas thanks to intelligible intelligence. It is an immediate knowledge, unlike the discursive knowledge of reason. It is the highest kind of science. It is distinguished as a bottom-up process until reaching the Idea of Good, and a top-down process back to the Idea from which it emerged. With dialectic, intelligence returns to the limits of the intelligible and reaches the highest point to which human knowledge can aspire. It is the most noble activity in which man can engage.
Cognoscible
Intelligible beings. Whether sensible objects are cognoscible is debatable. Although generally, cognoscible means ‘what can be known’, Plato applies it only to intelligible beings, since, if true, they only allow true knowledge (science).
Conclusion
In an argument, it is the result that necessarily follows from accepting its premises. There are two types of conclusions: In mathematical reasoning, the conclusion is never a beginning, as it depends on the premises from which it follows. However, in dialectic science, the conclusion is a beginning because its arguments spring from assumptions (the Idea below) that explain and justify the conclusion (the Idea above). Therefore, the conclusion is prior to the premises, which it explains. Here, the conclusion depends ontologically on the premises, but the premise depends on the conclusion.
Conjecture
“Knowledge” of images. It is the lowest type of opinion. Not proper knowledge, since it is the result of guesses, rumors, sayings, myths—knowledge in general without any basis, even in our sensory experience. It is “hearsay knowledge”.
Knowing, Knowledge
These terms do not refer to just any cognitive activity, but to the activity of the rational soul. Only it, by knowing intelligible beings, obtains true knowledge (science). The soul, through the senses, thinks, which is not exactly knowing.
Belief
“Knowledge” derived from the perceptions of natural beings (“animals” and “everything that grows”) and artificial beings. It is the highest form of opinion. It is not proper knowledge, as it is made without exceeding the scope of sense experience and without any intervention of the rational element.
Dialectic
This term has various meanings. Here are two closest to those presented in the text:
a) Broad sense: A knowledge process in two stages. First, the upward path (anabasis) from the sensible to the intelligible. This includes the educational process by which different levels of knowledge are surpassed. This is the meaning in the allegory of the cave. Intelligence, entering the realm of ideas, analyzes the relationships between them and their hierarchical structure. This dialectic allows first to pass from the multiplicity of the sensible to the multiplicity of ideas, and then to the higher ideas that unite to reach the Idea of Good, the ultimate unifying principle.
After reaching the Idea of Good, the process of descent (catabasis) begins: in the allegory of the cave, this is represented by the prisoner’s return. The philosopher who has known the Good re-educates others; that is, dialectic leads to commitment. In this way, the real location corresponding to each type of knowledge is recognized, as are the dependency relationships between people.
b) Strict sense: Dialectic science.
Education
The journey from ignorance (the view that the sensible is real) to higher knowledge (supreme study). Only philosophers complete this journey. The rest remain in intermediate stages and should be advised by those who know the Good. Education occupies a central place in the ideal state because it improves the public. By knowing the Good, one will act well (moral intellectualism); therefore, only education that teaches what is good creates better citizens. For the same reason, only those who know the Good, the philosophers, should be rulers. Good education is an exercise in which the teacher (played by the one who frees the prisoner) guides man to recall the truth he already possesses within him (nativism). Therefore, education is “the art of turning the soul’s ability to know in the easiest and most effective way” so that it knows what it is. This conception is opposed to the sophist view, which understands education as a process by which the teacher ‘transmits’ content and techniques. The educational role involves selection and training with a deep ethical and political sense. Education does not provide the soul with science because it already possesses it innately; its power is simply to train it, leading it from the sensible to the intelligible, whose ultimate expression is the Good.
Essence
What makes a thing a thing despite changes in its appearance or state. The nature of a being, when known, is included in the concept. The essence does not necessarily imply existence. The Idea of the Good is the only being that is not an essence.
Supreme Study
The highest knowledge the mind can access. Its object is the highest being, the Idea of Good. It represents the last stage of education of the philosopher-ruler. It is therefore the last step of dialectic science in its ascent and the first in its descent.
Dialectic Faculty
Intelligence. It is so named because this faculty knows Ideas by applying the dialectical ascent-descent. This is how dialectic science develops.
Idea
An intangible, immutable, necessary, universal, and absolute entity that exists independently of the sensible world and the thinking subject—that is, a being in and of itself. It is not a concept or mental construct. Ideas are objective realities; moreover, they are the only beings in the fullest sense, and from them derives all that is real in the sensory world. They are, therefore, the only real beings, since they are “what is” and, therefore, allow true knowledge—science, in particular, dialectic science, the highest form of knowledge. Some interpreters believe that mathematical objects are a type of Idea. Others interpret them, while maintaining their key features, as occupying an ontologically inferior position.
Man
The temporary and accidental union of two completely distinct and separate realities: body and soul (anthropological dualism). Of these two entities, the soul is the principal one; it is the cause of man’s being and what essentially defines him. The body is only a temporary prison for the soul.
Idea of the Good
The Idea that occupies the highest point of being. It is the supreme object of study. It is the cause of the goodness of sentient beings, ideas, private actions (ethics), and public actions (politics). It is the ultimate cause of the existence of sentient beings. It is also the cause of the nature and existence of Ideas and their truth (their being knowable). Finally, it is the reason why our souls come to know the Ideas—that is, why we have intelligence. The Idea of Good is not completely knowable, and its being is not reduced to an essence.
Ignorance
In the allegory of the cave, it is the situation in which the prisoners find themselves before the educational process. They are ignorant because they do not know that their knowledge is wrong: they believe they are encountering real people when they are encountering shadows. This image depicts ignorance as the situation of those who believe the sensible world is real. Their ignorance is not in knowing sentient beings, but in saying that such beings are real.
Images
Beings at the lowest level of sentient beings. They produce the lowest type of opinion, called conjecture. Images are shadows, reflections on water and any other surface producing reflections or images of superior sentient beings, natural and artificial beings. Images also include assumptions, rumors, sayings, myths, etc.—what is generally known by hearsay.
Intelligence
This term is used in two ways:
a) Intelligence and theoretical knowledge. In this case, it can have three meanings: Most often, it implies the highest faculty of the rational soul for knowing Ideas (the dialectic power). In other cases, intelligence is the knowledge resulting from that power (dialectic science). This use is less frequent. Finally, in one case (end of the allegory of the line), the term ‘intelligence’ means the actual activity of that power: the immediate (intuitive) knowledge of ideas.
b) Intelligence and practical knowledge.
Intelligible
A characteristic of intelligible beings, as they are knowable by intelligence.
Nature
What essentially defines a being, explaining its identity, changes, activities, and movements that take place within it non-violently. What happens in a being “naturally” is what takes place according to its nature.
Opinion, True Opinion
(Doxa) “Knowledge” that is not true, obtained thanks to the perceptions we have of sentient beings (which is why they are “debatable”). It is not true because it is not obtained from beings that are truly real, only sensible. There are two types of opinion: belief, knowledge of natural and artificial beings; and conjecture, knowledge of images. Opinion, by its non-real nature, is not proper knowledge. When one obtains an opinion knowing that this knowledge is not true, one obtains a ‘true opinion’. The difference with simple opinion is that those with a true opinion know that sensible beings are not real. Therefore, only those who have intelligence can obtain a true opinion.
Thought, Discursive Thought
The activity of reason (strictly speaking) by which mathematical objects are known. The term “discursive” refers to the processual character of this knowledge, as opposed to the immediacy of intelligence. Reason obtains mathematical knowledge from assumptions (assumptions it considers principles) to a conclusion, a necessary consequence of those assumptions and which, therefore, is never a beginning.
Principle of Everything
The Idea of the Good. It is the beginning of all because it is the ultimate cause of all beings and, therefore, explains all.
Unconditioned Principle
The Idea of the Good, because it is the only being whose existence does not depend on any other, since it occupies the highest point of being. Therefore, since its existence is not ‘supposed’ by the existence of any other idea, only it is an “unconditioned principle”.
Reason
In this excerpt, “reason” has a broad meaning. It refers to the soul’s ability to learn through its two faculties: intelligence and reason, in the strict sense. This latter sense, which does not appear explicitly in the text, refers to reason as the capacity to develop, through discursive thinking, mathematics.
Wisdom
One of the three virtues necessary to achieve justice in ethics and politics. Man will be wise if his rational soul is in control. The state will be wise if its rulers are wise. Man obtains wisdom when he comes to know the Idea of Good. This makes him a philosopher. These knowers of the Good are the ones who should govern the state so that it is wise.
Intelligible Beings
Immutable, necessary, and universal beings. They are therefore true beings. They generate true knowledge or science, so they are also seen as “knowable”, not debatable. Ideas can be structured hierarchically and are known by intelligence, as are mathematical objects, which occupy the lowest place of this type of being and are known by reason. They are the only ones that can be called ‘beings’, as they exist in themselves and for themselves: they are not affected by the physical world or by human subjects. Because of their immutability, they are ‘what is’. They are one of the two realms of being (ontological dualism). It is superior to the sensible realm, as the latter exists because of its participation in the intelligible.
Sentient Beings
Material, individual, multiple, contingent, and changing beings, which are born (have genesis) and die. Therefore, they are not “what is”, not true, but what becomes. Nor are they “in themselves” nor “by themselves”, but exist through participation in the Ideas. Because of this, they are less than intelligible beings, from which they are separate (ontological dualism). They are of two types: images, on a lower ontological level, and natural and artificial beings, on a superior level. Because of their characteristics, these two types of beings are known through the senses and do not provide real knowledge, but opinion. Therefore, instead of being knowable beings, they are debatable.
Shadows
In the allegory of the cave, this expression has an allegorical meaning. They can be the shadows of objects in the cave or of the prisoners, representing images, or the shadows of natural things from outside, which represent the lesser intelligible beings, mathematical objects. However, in the allegory of the line, “shadows” has no allegorical meaning; it refers directly to one of the types of sentient beings classified within images.
Assumption
A hypothesis or provisional assumption that is expected to justify a proposition. Plato distinguishes between two types of assumptions: those of mathematics and those of dialectic science.
True
Used in an ontological sense. Truth is intelligible beings, which are also said to be ‘knowable’ or producers of true knowledge (science). They define the scope of truth because they are ‘what is’—immutable beings and, therefore, identical to themselves. In the allegory of the line, “truth” is used in a relative sense. It is said that higher sentient beings are the “truth” in relation to images, which are ontologically inferior. But in relation to intelligible beings, some are more “true” than others.