Plato created the character of his teacher Socrates in Phaedrus to convey his own philosophical teachings which came to be known as Platonism.
In classical Greek philosophy psyche, meaning 'breath', was used as a synonym for the soul. Ancient Greek concepts about the soul diverged along with a particular epoch and philosophical school. The Epicureans believed that the soul was made up of atoms similar to the body. The Platonists believed that the soul was an incorporeal and immaterial core connected to the gods as well the world. Aristotle believed that the soul was an isolated entity connected with the human body.
Plato was first to advocate "immortality" of the human soul through his works Republic and Phaedrus. These are a series of famous dialogs that present Plato's own metaphysical, psychological, and epistemological perspectives. The differentiation Plato traces between the body and the soul was radical during his era and is one of the earliest forms of "mind-body dualism."
In Phaedrus, he states that the soul is without internal parts and hence immortal, whereas in Republic, he states that the soul has a complex structure and conflicts between three parts―the reason, the spirit, and the appetite―hence this theory is called Plato's Tripartite Soul Theory.
The Concept
Plato divides the human soul into three parts: the Rational, the Spirited, and the Appetite. The Rational part desires to exert reason and attain rational decisions; the Spirited part desires supreme honor; and the Appetite part of the soul desires bodily pleasures such as food, drink, sex, etc.
Plato's Idea of the Tripartite Soul
▶ Plato explains through metaphors, and associates the human soul to comprehensive theory of the human psyche and an individual's designation within the wider society. The theory is based on the principle that the intimate psyche of an individual is correspondent to the composition of external society. Plato distinguishes the psyche as three constitutive parts, the rational, the spirited, and the appetite. The theory states that every individual's character is determined by the dominant constituent part of the psyche. Plato defines a moral individual as the one who has attained supreme control over the spirit and the appetite through his rationality. This he applied to the three classes in the society, namely, the ruling class, the military class, and the commoners. The ruling class exhibited dominance towards rationality, the military class towards honor, and the commoners towards appetite.
The Rational
symbolizes the mind and represents the ruling class, a rational mind thinks, analyzes, and gauges options for the best outcome of any given situation. It denotes conscious awareness and works for the benefit of the entire soul, thus making it wise. The ruling class is always superior as they take optimum decisions for the welfare of society as a whole and rationally rule their kingdoms, hence they fall in this category.
The Spirited
symbolizes the heart and represents the military class. Courage is the highest virtue of the spirit, and it's associated with bravery, honor, and overcoming great challenges. Individuals who are ruled by the heart are hot-blooded like the soldiers who face adversities with great strength and overcome it with pride and honor to attain victory.
The Appetite
symbolizes the stomach and represents the commoners, desire is ruled by sexual gratification, greed for money, comfort foods, and various other necessities that mostly take up an individual's life. These individuals are just fulfilling their day-to-day obligations and not reaching out for a higher goal.
▶ Another important allegory that Plato describes in his work Phaedrus, which goes parallel with the Tripartite Soul Theory, is that the soul is a charioteer (rational) controlling two winged steeds: one white (spirited) and one black (appetite). The main goal of the charioteer is to ascend to divine heights, but the black horse always poses problems and the chariot keeps falling back to earth.
A literal meaning would be that the soul seeks spiritual attainment but the worldly cares of the universe pull it back from its divine goal. According to Plato, the whole purpose of the soul was to attain perfect knowledge form like the gods―truth, justice, beauty, and rational knowledge. He believed in the notion of reincarnation and that a soul perfected itself with every reincarnation.
He proposed that reason must conquer over earthly desires in order to recollect perfect knowledge and rise towards heaven in winged horse chariots like the celestial divine beings.
Criticism and Arguments
▶ The tripartite quality of the soul is part of the central theme in Republic to identify justice in the individual. Plato limits the scope of desires by defining them as simple means of gratification. A human mind consists of various unfinished desires or requests, and he assumes that these competing irrational desires are of different reflective nature rather than elaborating on each of them or supporting the cause.

▶ Plato assumes that children and animals do not use rational thinking, and this aspect fails to provide any base in his dialog.

▶ Perhaps one of the most debatable aspects of the theory is the way it undermines the rights of an individual with regard to a wider society. Philosophers John Locke and Emmanuel Kant criticize this theory by emphasizing on strong notions regarding the rights of the individual, and indicate that they should not be subdued in favor of the well-being of the larger community. Kant debates that human beings have fundamental rights and that one should"Always recognize that human individuals are ends and do not use them as means to your end." But Plato vindicates that individuals must be used in order to attain social goals. Ernest Barker argues that this very precept could earn Plato's said democracy the title of the first communist state. He argues that the way in which Plato conceptualizes the individual as being in the highest state of ethics when he is promoting the greater purpose of the state, is twinned with many modern communist organizations. "If the world is one, and works towards one end, then the state is part of the world, with an end subsidiary to its end, and the individual again is part of the state, with an end subsidiary to the end of the state." In this theory, the roles of the government as well the individual in it, both, seem unattainable and undesirable. Many enlightened philosophers think that a society should not be based on just the morals of its citizen, John Locke indicates "It can have no other or measure, when in the hands of the magistrate, but to preserve the members of that society, in their lives, liberties and possessions; and so cannot be an absolute, arbitrary power over their lives and fortunes, which are as much as possible to be preserved."

▶ Aristotle conceived that the soul was part of the body which made it come alive, hence he argued that the soul cannot be divided into parts without being unified. He further argues that even if the soul be divided into parts, then it should be more than three as there are other powers related to the soul like nourishment, perception, and imagination. Secondly, he questions whether the tripartite structure easily fits empirical evidence. He states that some plants and insects, when bisected, carry on surviving. Aristotle believed that part of the soul resides in every living organ of an organism.

Aristotle's concept of the soul is not as concerned with immortality. He is concerned with the operating of the soul in all its various powers through the various organs in the body, be it a human, animal, or vegetative body. Thus, Plato's theory deals with only the rational and the struggle of the soul's immortality, it does not explain the facts and true functions of the soul.

Through these insights, we learn that Plato's theory of the soul legitimizes several aspects of pre-socratic theories such as renascence of the soul and the afterlife, but it seems the major flaw is the failure of the analogy between the mortal and society.