Definition of knowledge:
Plato defined knowledge as 'justified true belief' wherein before someone can claim to have knowledge of a proposition, 3 requisites need to be met:
The proposition must be true
It is believed to be the truth
The belief of truth is justified
Plato's true belief theory came to be questioned when it was discovered that there are some situations that meet the above requisites but philosophers disagreed that anything can really be known (Wikipedia the Free Encyclopedia, 2009).
Origins of knowledge:
Plato claimed that knowledge emanates from an elevated realm within one's soul where paradigms for perfection and virtues are stored. These paradigms serve as role models for humans to emulate. But due to varying levels of consciousness, people also vary in their ability to recognize truth, beauty and moral virtues (Campos, 2011).
It is Plato's contention that knowledge of the ideal world is inborn. Education and arts merely serve the purpose of aiding in the recall of origins and experiences of one's past as a means of moving towards perfection (Campos, 2011).
Senses or the mind:
Plato pointed out that reality cannot be perceived from the fluctuating nature of the senses unless the mind imposes stability and organization. The reality of the forms needs to be resorted to in order to understand how this happens. Forms are the unshakable ideals which material reality needs to conform to in order to exist. And, as ideals, these can only be arrived at through rational reflection (McGroggan,2008).
Reality refers to the permanent forms or ideals, while illusion or opinion refers to the evolving realm of appearances perceived by the senses. Plato claims that human perceptions acquired by the senses are only appearances, but are still reflections of reality. As humans have a deeper understanding of reality, they move away from vague and unjustified opinions (which were previously only based on the senses). The journey towards the truth starts from the rational reflection of concepts (McGroggan, 2008.
Methodology and Analysis:
Plato resorts to the use of metaphors to impart his metaphysical views. In his book, The Republic, he imparts his views through the character of Socrates. There are 3 metaphors which need to be understood to get to the heart of Plato's theory on knowledge (Wikipedia the Free Encyclopedia, 2009).
Metaphor of the Sun - Socrates used the sun as a symbol of intellectual enlightenment. He referred to the eye as the most unusual among all the organs since it cannot operate alone. It needs light, and there is no greater source of light than the sun. Therefore, the sun, because it allows us to see things clearly, will also show the way towards ultimate reality (Wikipedia the Free Encyclopedia, 2009). In Book 6 of the Republic, Plato further uses the eye as a metaphor to describe the soul: "...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 (trans. Jowett)?"
Allegory of the Cave - Socrates used a group of people who are chained to the wall of a cave. They watch shadows on the wall project by objects passing before a fire behind them, and start to get ideas about the shadows they are watching. As these people have been chained all their lives, the shadows they see are the extent to which they view reality. This metaphor was used in contrast to a philosopher who is freed from such chains. Having the freedom to see the true form of reality, he will come to the realization that the shadows do not reflect reality (Wikipedia the Free Encyclopedia, 2009).
The divided line - this line has 2 parts, 1 representing the intelligible world and visible world. These 2 parts are further divided, the subsections within the intelligible world representing higher and lower forms, and the subsections within the intelligible world representing ordinary objects and their shadows. The lines are of unequal lengths which represent their clarity and obscurity, which in turn represent the human status of either having knowledge or opinions (Wikipedia the Free Encyclopedia, 2009).
Also in Book 6 of the Republic, Plato further explains what he intends these subsections to indicate:
"...let there be four faculties in the soul-reason answering to the highest, understanding to the second, faith (or conviction) to the third, and perception of shadows to the last-and let there be a scale of them, and let us suppose that the several faculties have clearness in the same degree that their objects have truth (trans. Jowett)." At the heart of these 3 metaphors is Plato's complex theory about the Form of the Good (some writers have interpreted this to mean Plato's God). This is the ultimate form, which explains all other forms, and which is the source of all other forms. This Form of the Good functions in the same way as the sun as it shines and generates light for the perceptual world (Wikipedia the Free Encyclopedia, 2009).
In another portion of Book 6 of the Republic, Plato explains what he means by 'good:'
"...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 (trans. Jowett)."
In other words, truth can only be known when illuminated by the idea of good (Jowett). Argument as to what constitutes knowledge: Plato argues that knowledge is inborn, and learning is the development of ideas which have been lying dormant in one's soul. He believed that the soul came before birth with the "Form of the Good" already intact along with the perfect knowledge of everything. Therefore, he equated learning to recalling (Campos, 2011).
Plato also distinguished knowledge from opinion, the former being certain while the latter is not; opinion is arrived at through sensation which may be shifting, while knowledge is arrived at through the contemplation of permanent ideas (Campos, 2011). In Book 7of the Republic, Plato made an interesting claim on knowledge and its effective retention on the mind:
"...a freeman ought not to be a slave in the acquisition of knowledge of any kind. Bodily exercise, when compulsory, does no harm to the body; but knowledge which is acquired under compulsion obtains no hold on the mind (trans. Jowett)."
Does Plato argue for absolute or relative knowledge? Plato argues for absolute knowledge. But as the above accounts will indicate, he also recognizes that this can only be arrived at through an abandonment of the superficial perceptions of the senses and ascension towards one's inner self through the process of reflection. In other words, he believes absolute knowledge is possible through the process of self discovery. Plato also recognizes the existence of relative knowledge but points out that this is not real. This is the consequence of the incomplete interpretation of the senses, and this incomplete interpretation is the reason why there is a need to search deeper for the complete truth.