Here's a link to the REPUBLIC. http://classics.mit.edu/Plato/republic.html
The philosophical discussion grounded by Plato in The Republic, shows a difference between opinions and genuine knowledge through Plato’s metaphysical, psychological and epistemic concepts. Plato’s epistemic justifications of knowledge and opinion lay in two different realms. Plato goes further into aligning his epistemological account with his metaphysical account of the theory of forms. Plato also adds a psychological underlining to his account of knowledge and how we know through the tripartite soul. Plato’s epistemology and metaphysics consists of three key devices. They include the allegory of the cave, the divided line, and the sun analogy. The three devices allow for Plato to establish his epistemology and metaphysics. In this paper, I will explain the difference between Plato’s understanding of genuine knowledge and right opinion through the psychological, metaphysical and epistemological approach.
Plato’s metaphysical approach investigates questions about what is most ‘real’ in the universe. Plato uses the theory of the forms to state his claims on the distinction between genuine knowledge and opinion. Plato’s theory of the forms is to be understood as two realms which hold two different kinds of things. One realm is the realm of being, which holds things called forms. The realm of being is unaffected by space and time, thus being unchanging and not physical. These forms are inside the realm of being and they are intelligible things. Forms are concepts of universal things, such as the form of good, form of beauty and forms of mathematical concepts such as triangles, circles and squares. Knowledge is not the forms, but we do have knowledge of the forms using the faculties of our mind. To gain the epistemic status of knowledge, we must either use the cognitive faculty of reasoning or/and understanding to know of the forms in the realm of being. Plato believes that what is real is not what we see, but what we understand through the forms. What is real cannot be found in the material world—rather what is real is what can be found in the world of reason and understanding. The theory of the forms is what is the most real in the universe. Plato believes forms are the essence of all objects and knowledge is granted through understanding and reasoning of the forms.
The other realm is the realm of becoming, which holds things called sensible objects and images of objects. The realm of becoming is the world of appearances and is changing constantly. These sensible objects are the particulars of concepts, such as a thing, a person, an animal, and animals. The images of objects are the reflections of objects and shadows. Opinion is to be understood by this realm. Opinion is granted epistemically by using the faculty of belief and/or imagination to understand the objects in the realm of the becoming. Plato believed that which is always changing cannot be true and genuine. Plato thought he would explain the changing of the world as the becoming and the eternal world as the being. Opinions are always changing, while knowledge is fixed. Knowledge is absolute and eternally true. Thus, knowledge is what is real and true.
The different degrees of perception that underlines the difference between knowledge and right opinion is best understood with the device Plato calls the divided line. Imagine a line that divides a page unequally, so we have a bigger top than the bottom. Plato states there are two kinds of things: visible is the bottom and intelligible is the top (509e). The divided line shows the perception going from illusions in the world at the bottom to the pure and what is real of reality, which is the forms, at the top. The visible can be understood as the realm of becoming. The intelligible can be understood as the realm of being. Imagine that the top side has knowledge and the other has opinion. Using the faculty of our mind, we can have two outcomes in the realm of the becoming, and those are imagination and belief. Using the faculty of imagination, we see images of objects such as reflections of shadows (509e). While using the faculty of belief, we see sensible objects such as people, animals, and artifacts (510a). The faculty of imagination and belief never attain knowledge and are strictly opinion. Right opinion is the extreme of the opinion, being the highest point in the realm of the becoming. When we use the faculty of reasoning, we attain knowledge of mathematical forms such as triangles, circles, and squares. When we use the faculty of our understanding, we attain knowledge of the forms of justice, love, and beauty. The outcome of both the realm of being and realm of becoming distinguish a metaphysical account of reality. In the realm of being, we have knowledge of the forms. In the realm of the becoming, we have opinion based on the objects and particulars of the world.
Knowledge, opinion, and ignorance can be understood as knowing and not knowing. Knowledge is of what is (477a1). Knowledge is unchanging and perfect. Knowledge could be understood through the forms, so knowledge must be or what is real. Ignorance is of what is not (477a3). There is nothing and that cannot be knowledge, thus it is not. Belief or opinion is of what is and what is not (477a-b). Opinion or belief is based on the senses of reality. Opinion is not knowledge, so it cannot be what is nor can it be ignorance. Thus, opinion has to be what is and what is not. Opinion is an intermediate between knowledge and ignorance. Opinion is changing and not perfect. The difference between genuine knowledge and right opinion is that knowledge will always succeed, whereas opinion will succeed at times (Meno 97c). Opinions can change or they can be false. True opinion is the extreme of the opinion being actually true instead of the possibility of being false. Socrates states that if someone who has the right opinion to a certain path, but does not have knowledge of that path or has gone there, would not be in any worse position than a person who has knowledge of the path (Meno 97b), yet knowledge is prized higher than true opinion. True opinion does not remain in the mind and opinion is not tied down. True opinion/belief becomes knowledge when true opinion is accompanied with reason, thus allowing true opinion to become a kind of knowledge. Knowledge is prized higher and differs from true opinion, because knowledge is tied down and remains in the mind (Meno 98). We attain an opinion when we use the faculty of belief based on the sensible particulars that may or may not be true. True opinion is when a person is correct based on the sensible particulars and has the best epistemic status in the realm of becoming.
Plato introduces the human soul as immortal and that it has three distinct parts. Socrates states an individual has the same three parts in his soul as the city (435b). He identifies a rational part of the soul that lusts after truth, a spirited part of the soul that lusts after honor, and an appetitive part of the soul that lusts after everything else, including food, drink, sex, and especially money. He emphasizes that the soul is the entity that has knowledge and that we do not learn anything, but we recollect. Recollection is when the soul comes to remember what it already knew before its current human life span (Meno 81d). Socrates shows Meno that he is recollecting by asking him what is twice of the square that was divided into two but has twice the length of the original (Meno 82c-e). Socrates states when men are interrogated in the right manner, they always give the right answer on their own, and they could not do this if they did not possess the knowledge and the right explanation already inside them (Phaedo 73b). This means that we can only consider what we know by recollecting using the faculty of our minds.
Plato claims what we can know through his psychological account of the tripartite soul being immortal. Plato states we do not learn, but recollect on what we already know (Phaedo 75). We cannot possibly have knowledge through our senses, so we must have knowledge through the forms. We must have the knowledge of the forms prior to our birth, because how else would be obtain the knowledge of the forms, since it cannot be through our senses. Our senses only lead us to opinions. Plato states that our knowledge of the forms is tied to the soul. Knowledge is eternal and perfect such as one plus one will always equal to two. Our soul must have that knowledge, thus making the soul immortal and making our knowledge of the forms prior to birth, a requirement to knowing.
Using the allegory of the cave, Plato explains the difference between genuine knowledge and right opinion. The allegory of the cave portrays a prisoner chained, that have never seen the outside. Everything the prisoner believes to be real exists only inside the cave. The prisoner’s knowledge is certainly limited. If the prisoners were to go outside the cave, they would be educated about the world. Their reality would change drastically. This transition from dark to light, or uneducated to educated, is the transformation that Plato says is required to gain genuine knowledge. From belief to reason and understanding is the transformation which could be understood as the epistemological approach. Plato uses this allegory to show a distinction in cognitive states. The prisoner’s knowledge is structured on beliefs and imagination. Plato correlates this cognitive state to the tripartite soul. This is because people are consumed by the desires and lust for material wealth. They do not pursue reason and understanding that will lead to genuine knowledge. Therefore, Plato says knowledge based on belief must be regarded as opinion rather than knowledge.
It is in understanding the form of the good, in fact, that someone gains the highest level knowledge and thus becomes fit to be a philosopher/ruler. Although, Socrates is not able to describe the form of the good explicitly, he attempts to give us a sense of it by comparing it to the sun. It is only when a man grasps the form of the good that he achieves the highest level of cognition and understanding. Socrates explains that the form of the good is not what is commonly held to be good. Some think that the highest good is pleasure, while the more sophisticated think that it is knowledge. In fact, it is neither of these, but Socrates cannot precisely say what it is. The sun is to the visible realm what the good is to the intelligible realm in three respects. First, while the sun is the source of light, and hence, visibility in the visible realm, the good is the source of intelligibility (508e). Second, the sun is responsible for giving us sight, because it is only by incorporation of sun-like stuff into it that the eye is enabled to see. Similarly, the good gives us the capacity for knowledge. Finally, the sun is responsible for causing things to exist in the visible realm. The sun regulates the seasons; it allows flowers to bloom, and it makes animals give birth. The good, in turn, is responsible for the existence of forms. The form of the good is responsible for all knowledge, truth, and for the knowing mind. It is the cause of the existence of the forms in the intelligible realm, and the source for all that is good and beautiful in the visible realm. It is not surprising, then, that it is the ultimate aim of knowledge.
Plato’s epistemology and metaphysics are explained by the allegory of the cave, the divided line, and the analogy of the sun. It is also important to understand the three concepts Plato uses to establish his epistemology and metaphysics and differentiate between genuine knowledge and right opinion. It is by understanding the forms that one can attain knowledge and to keep in check the opinions of the sensible reality we live in. Genuine knowledge is only accessible to those who attempt to grasp the faculty of understanding and reason, thus making them only a contender to be a philosopher king or queen.