On the Soul

Plato is believed to have mentored Aristotle, and yet, their philosophies are miles apart. Where Plato is vague, Aristotle is vivid, where Plato is an idealist, Aristotle is a rationalist and a realist. This results in a very interesting dichotomy: The liege vs the prodigy, and Idealism vs Realism.

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Aristotle with Plato in The School of Athens
Raphael, The School of Athens, 1509–1511, fresco at the Raphael Rooms, Apostolic Palace, Vatican City

Aristotle (384 BC – 322 BC) – Philosopher, Polymath

In De Anima (On the Soul), Aristotle discusses the nature of the soul and its properties. This is obviously a broad question, and Aristotle manages to address it rather successfully.

To understand how Aristotle’s view compares to Plato’s tripartite theory of the soul and to understand Plato’s theory itself, it is first crucial to understand the ‘how’ and ‘why’ of their opinions, meaning their greater metaphysical theories about our existence and the world we live in.

Aristotle’s realism and Plato’s idealism

The two philosophers are known in history as an antagonistic pair, teacher versus student, idealist versus realist. It is the last distinction that makes for the most interesting discussion.

While Plato firmly supported the existence of a world of ideas, completely separate from our materialistic world, Aristotle claimed that our purest and most fundamental ideas about the world are derived from our tendency to think inductively. Which is to say that we infer basic rules and principles from our everyday experiences.

In essence, Aristotle thought that we are governed for the most part by logic and not by the existence of a separate, pure and perfect existence. This pure existence is encapsulated in Plato’s theory of forms, according to which every object or concept, such as a chair, a book, or even good and evil, have a perfect form in a separate world which we can’t reach or grasp. The manifestation of these objects and concepts in our realm is never perfect and this is why we can’t discover them as they are.

In his work, Aristotle is organized and rational. He never sticks to a theoretical idea without supporting it with evidence from real life. He is practical, a non-polemic realist who nevertheless aims to bring people closer to the ideal model of man.

Plato, however, was poetic in his work. He was gifted with words, but many doubt the validity of his claims. He often makes use of the Socratic method, creating discussions between Socrates and other Athenians to demonstrate self-evident truths. This is because he believed that everyone knows the truth from the moment of their birth, but with age this truth gets forgotten and can only be found again with inquiry and rationalization. He is not empirical, as he already knows the conclusion of his proof, merely constructing arguments that will fit his worldview in the process.

This ideal polity (=a group of people with a collective identity) presented by Plato in The Republic is a philosophical work disguised as a political text. Plato does not discuss policy specifically, but comments on different forms of political organization. He presents the ideal polity, which he terms as utopia (>ουτοπία= ου(never) + τόπος (place) ). This “neverland” is the place where justice rules and good thrives.

It is essentially a polemic for the soul, a plea for man to embrace justice, to always practice it, to remain a good and healthy man, both physically and mentally, and to serve his role in society in order to work towards this politea and ultimately, towards justice.

This soul is interpreted differently by both Aristotle and Plato. However, it always retains its element as the most important aspect of mankind, one that must be recognized, nourished and kept just and good.

Plato’s Tripartite Theory

In The Republic, Plato introduces his tripartite (3 parts) theory about the soul. He relates the soul to the composition of the society, believing that a man’s place in society – in the ruling class, the military class, or the commoners – determines the composition of his own intimate soul.

He explains that the soul is divided into three sections. The first is the rational part. This part of the soul makes humans wise and capable of making sound decisions. This is the conscious part of the human mind, the one with which we can safely organize our societies. This is why it is the most powerful in rulers.

The second is the spirited part, which belongs to the military class. It is characterized by courage and strength of character only found in individuals with thirst for glory and honor. It is the most powerful in people who, when faced with adversity, overcome obstacles with persistence and face dangers with bravery.

The third is the appetite, which is the black horse mentioned above. This symbolizes the stomach and denotes the desires of the commoners, namely sexual gratification, greed etc. These people live on a day to day basis, lacking a higher purpose in their lives.

In Phaedrus, Plato argues that the soul is immortal and self-moving. The soul is separate from the body and is divine in its existence.

Aristotle with Plato in the The School of Athens - Close up
Detail of The School of Athens, showing Plato (left) and Aristotle (right)

In its earthly form, the soul is responsible for all of man’s actions because the body itself is useless without it. Plato claims the soul is nourished with the divine, with beauty, wisdom, and goodness, but wastes away when fed with evil. He also ties the soul to his theory of forms. He writes that the soul is the carrier of the divine intelligence that men seek to discover, hence humans are inquisitive.

Plato gives an allegory for this fight of the soul. He calls the soul a charioteer (therefore it is rational) that controls two winged horses: one white (spirited) and one black (appetite). The white yearns to ascend to the Gods but the black horse constantly creates problems, so the chariot never completely ascends to the sky. This is in par with reality, where the soul is eager to reach the Gods and perfection, but can never do so because of reality. With each reincarnation, however, the soul can go to greater and greater heights.

Plato doesn’t give an adequate proof of his view on the nature of soul, but this is something any one of us can excuse given the time period and the obscurity of the subject. And for the same reasons, reading Aristotle’s treatise on the nature of the soul makes one gleam in awe at the philosopher’s scientific line of thought.

Aristotle’s De Anima

In De Anima, Aristotle introduces a more rational approach to the nature of the soul. He begins with a series of observations about the nature of humans and other organisms, such as our perceptions, metabolism, and reasoning, in order to describe the function of the soul for mankind.

That is, the soul of every organism is responsible for its ability to carry out these functions, but not directly responsible for each function itself. Meaning, it is not the soul that causes us to think or desire. These happen entirely due to our complex biological structures. However, only the soul has the ability to manifest these functions in our body. Doesn’t it sound awfully like the brain?

Astonishingly, it was unknown to Aristotle that in humans and many other organisms it is the brain that serves this purpose. Although Aristotle failed to recognize the importance of the brain and instead called the heart and the seat of the soul, he predicted, in essence, the function of the human brain.

Aristotle doesn’t share the dualist view of Plato. Although he does support the separate concepts of soul and body he does not think they are independent of each other. As a monist, he insists that the soul is not from another realm, but that it is an inanimate entity that begins to exist when the body is born and ceases to exist when the body is dead.

However, these abilities are not only physical. We don’t only sense, metabolize or create arguments. We do not just receive data, process it and make conclusions. We don’t just work to eat, sleep, to get through the day. As sentient and intelligent beings, we humans have cognitive abilities that surpass those of other animals. We can hope, dream, fantasize, create words, pictures and sounds etc. In a way, we replicate gods themselves when we indulge in fantasy and creation. These are also actuated by the soul.

Aristotle claimed only living things have soul. He found that living beings are only plants, humans and other animals by observing the common characteristics of our species. In fact, the soul is what makes them living beings, because they all have the following abilities more or less; we are all self-nourishing, we grow and reproduce, we decay in the end, we can move autonomously and rest as well, we can perceive the world around us with our five senses and one which is exclusive to humans: we have intelligence. As you might have noticed, these are the criteria used today to determine what is a living organism.

As a general theory, Aristotle cites the following functions of our soul: growth and reproduction, movement and perception, and intellect. From these three functions, Aristotle inferred three degrees of the soul; the nutritive soul, the sensitive soul( found not in plants but only in humans and other animals), and the rational soul, found solely in humans.

Lastly, the soul is not personal. Although we all have different souls as different beings, these are the same kind of souls. Therefore, we’re dealing with something universal; the soul is the capacity of life. And it is this capacity of life that only the body can truly bring to life. As Aristotle writes:

“Soul and body react sympathetically upon each other […]. The soul suffers when the body is diseased or traumatized, while the body suffers when the soul is ailing.”

Further Reading