Aristotle on the Soul: vegetative, sensitive, and intellectual

Aristotle dealt with the nature of the soul in his classic work called Perí psychés (On the Soul), or De anima in the Latin translation. In this work, consisting of three books, Aristotle discusses the theories about the soul elaborated by his predecessors, pointing out their mistakes and successes; and then he presents his own conception of the soul.

To understand what is soul for Aristotle, it is also necessary to understand some fundamental concepts of his metaphysics, as we will see in the course of this article.

What is soul according to Aristotle?

According to Aristotle, the soul is a substance as a form of a natural body that has life in potency. And as substance, in the sense of form, the soul is act (Entelechy, in Greek) of the living body.

This is the first definition of soul presented by him at the beginning of Book II of De anima. We will analyze this definition further.

Read more: What is act and potency according to Aristotle? Definition and examples.

Body and Soul in Aristotle

In order to understand the definition of soul presented above, we need to resume some metaphysical concepts implied in it, especially the theory of hilemorphism.

According to Aristotelian metaphysics, one of the genera of being is substance.

But what is substance?

Substance can be understood in three senses:

• matter: meaning something not determined;
• form: by which something is determined;
• composed of matter and form;

Since matter is not something determined, it is pure potency; form, on the other hand, is act. Compound substance means the union of matter and form.

Natural bodies are composite substances. When Aristotle speaks of body, he is not referring, at first, to the human body, or to the body of any living being. Body is, here, understood in a general way, and can mean both living and non-living bodies. As Aristotle says:

Among substances are by general consent reckoned bodies and especially natural bodies; for they are the principles of all other bodies. Of natural bodies some have life in them, others not; by life we mean self-nutrition and growth (with its correlative decay). It follows that every natural body which has life in it is a substance in the sense of a composite.

(De anima, Book II, 412a 11).

Some natural bodies have life, such as animals, others have no life, such as, for example, a stone. What is the essential difference between the two?

What makes a body have life is precisely the soul. The soul is the principle (cause) of life, and this is the essential difference between a living and a non-living being.

The body (matter) has life only in potency, but it is the soul that acts as the first principle (act) that actualizes this potentiality of the body.

Aristotle also talks about the tripartition and functions of the soul.

Tripartition of the soul

Aristotelian psychology encompasses the three kingdoms of life: plants, animals, and man.

Therefore, for Aristotle, there are 3 types of soul with different functions.

1. vegetative soul: principle of plant and animal life;
2. sensitive soul: principle of movement and sensibility in animals;
3. intellective soul: by which man possesses movement, sensibility and intelligence;

Let’s look in detail at the function of each type of soul.

a) The vegetative soul

The vegetative soul, also called the nutritive soul, is responsible for the most elementary functions of life, such as:

• nutrition;
• growth;
• reproduction;

Plants are living beings that have only these functions. They are born, nourish, reproduce, and die. Therefore, plants are perfect examples of living beings that possess the vegetative soul. However, the vegetative soul is not exclusive only to plants.

Obviously, animals are also born, grow, and reproduce, that is, they also have a vegetative soul.

However, animals have other very specific functions, such as the ability to move around and to feel, functions that are beyond the vegetative soul.

b) The sensitive soul

Aristotle points out in his reflections on the soul, that there is another characteristic found in living things:

• sensory perception;
• appetite;
• movement;

Sensory perception refers to the five senses; not all animals have all senses, but they all possess the most necessary one, which is, according to the Greek philosopher, touch.

And if animals have perception, then they also have appetite (desire, impulse, will), because the ability to feel implies feeling the pleasurable and the painful. For example, when the animal perceives food, the desire to satisfy its hunger arises.

From appetite derives movement. Through sensation the animal captures that which is desirable and pleasurable, and moves to achieve it. Movement and desire, therefore, are closely linked.

c) The intellective soul

The intellectual soul is responsible for intellectual operations. It is through it that man is a rational being, capable of thinking and understanding.

Man is the only species that possesses the functions of the vegetative (nutrition, growth, etc.), sensitive (perception, desire, movement) and intellectual soul.

This does not mean that man possesses 3 souls together. In fact, the intellective soul, being superior in nature, performs the functions of the other types of souls.

This is also the case with animals, which, because they have a sensitive soul, perform the functions of the vegetative soul.

Therefore, there is a “hierarchy” in Aristotle’s theory of the soul, where the intellective soul is at the top.

Conclusion

The soul was the subject of much philosophical reflection before it became the object of scientific psychology. The philosophers developed what became known as rational psychology, whose goal was to rationally answer questions such as the origin, functions, and destiny of the soul.

Reading his writings, one realizes that Aristotle had an incredible scientific spirit, which is why he is considered the father of many sciences: physics, biology, psychology, etc.

The goal of “Aristotelian psychology” was to investigate life and its most particular manifestations and group them into a well-structured philosophical system.

The concept of soul for Aristotle is not a type of spirit that inhabits or commands the body. Aristotle saw the soul simply as the principle that makes an entity (body) have life. Therefore, there is an identification of soul (psyche) and life (zoe).