The Theory of the Soul in Aristotle

By Maurizio Bisogno

The philosophical psychology of Aristotle. Treaty on the nature of the soul.

According to Aristotle the soul is “the actuality of a body that has life”. This short article will try to clarify the meaning of this statement.

The idea that the soul is divided into several parts and faculties comes from Plato, the difference is that Aristotle’s theory is rooted in the study of biology.

For Aristotle the “true essence of the soul is defined by its relationship with an organic structure”, p. 192, Kenny.

“In the Phaedrus Plato imagines the human soul as a winged biga [a two-horse chariot], guided by an charioteer (the rational soul) and drawn by two horses: one, of generous race, representing the irascible soul connected to the higher passionate elements (courage, disdain, etc.); the other, of an ignoble race, representing the lustful soul, connected to the lowest instincts (love of pleasures, etc.). It was the dominance of the latter that caused the soul to fall and [caused] its imprisonment in the body.” p. 174, Geymonat, Vol. I

Aristotle dealt with the problem of the soul in the Eudemus (on the immortality of the soul), The Soul (Peri psychés), The Senses (Perì aisthéseos kaì aistheton), The Memory (Perì mnemes kai anamnéseos).

What A. Kenny says we also find it in L. Geymonat “… in his later years, Aristotle moves to an antithetical position [to the Platonic one], seeking precisely in the structure of the body the root of the perceptual faculty. It can be said that, in this last stage of his thought, he conceives body and soul, no longer as two strangers unnaturally linked to each other, but as complementary to each other, as matter and form of the same individual.” p. 218, L. Geymonat  [my italics]

However, we will see that the interpretations will have to take a different turn thanks to a famous Aristotelian passage. But for the moment let’s stick to the explanation of the monistic version of the Aristotelian conception.

If we mean a living substance like the compound of matter and forms, the soul is the form of a natural body.

But what does Aristotle mean by ‘body’? He intends mainly three things:

1. a living compound substance

2. the type of material suitable for receiving a form

3. the organic body, a body that has organs – parts with specific functions

in all three of these cases the soul intervenes as a form of the body.

Let’s take the case of a tool like the hammer: the function of the physical body is a bit like its soul. This understanding becomes even clearer to us if we take the case of an organ like the eye: if it were an entire animal, its function of seeing would be its soul.

The soul is an actuality (act). [ This is the opposite of potentiality]

Acts are divided into first actuality and second actuality.

First actuality is when the eye exercises its function of seeing; or when the hammer exercises its function of hammering.

The first actuality is the potential, that is, it is the hammer at rest, or the sleeping eye; they are in possession of a power they are not using.

The soul is the first actuality of a living body: the body implements all the vital operations of the organism – this exercise is its soul in progress (second actuality).

This distinction is very important to understand later how we can talk about dualism in Aristotle.

Not only is the soul the formal cause of the living body, but it is also the final principle, the moving principle – the principle of change in the body.

The ascending hierarchy of souls.

The Plants have a vegetative soul which makes possible nutrition, growth, and reproduction.

The Animals have this vegetative soul and also have the powers of movement and perception.

The Humans have the previous one and have more reason and thought logismos kai dianoia – they have the rational soul.

Aristotle lies between Plato and Descartes not only in chronological terms, but also as he creates an alternative to dualism: for Aristotle the soul is not an immaterial, inner agent acting on the body. In fact: The soul does not need to be divided into parts as is the case for the body; the parts of the soul are faculties that differ in operations and objects. Seeing is a different activity from hearing because colors are different from sounds.

The soul is the actuality and distinctive function of a living being.

Since the distinctive trait of man is his rational soul, it follows that the “happiness” of man consists in doing well what distinguishes him from animals, that is, man must use his rational excellence if he wants to be happy. Man must exercise thought.

The latter can be directed in one of the following two directions: either as a guide to action or as contemplative knowledge. And consistently with this alternative, Aristotle develops its ethics.

He roots the moral reasoning – rationality – in physics, in the knowledge of the human, more particularly in his senses.

Here need to relate a specific Aristotelian distinction between objects of the senses that are perceived by a sense, for example colour is perceived by sight and objects of the senses that can be perceived by more than one sense, such as moving objects. Movement is a common impression caused by more than one sense as there is no specific organ in us to which it corresponds. We can perceive a common impression thanks to the faculty called “common sense” koine aisthesis. In fact, for Aristotle when we meet a horse and recognize it as such it is because our intellectual faculty brings together the different sensory perceptions in a single concept or image – so it is the function of “common sense” that unifies the different perceptions that come from the same object. This unifying process is called abstraction.

The analysis of the five senses, the ability to feel and the possibility that an object has to be perceived/heard, merits a separate chapter; let’s just remember here that the Aristotelian thesis according to which the ability to perceive (feel) in actuality is the same thing that the ability of the object to be perceived, this thesis plays an important role in the philosophical analysis of senses perception (perceiving) as it avoids the need to introduce a passage (therefore also a means) between the mind and the representation of what has been perceived.

Let us go back to the philosophical reasoning of Aristotle, that which connects the senses to the soul, and let us say that in addition to the five senses he recognizes other faculties that he names as the ‘internal senses’.

The part of the soul that corresponds to the senses, that locus which cognitively reflects the senses, is the seat of the irrational soul, which is different from the vegetative soul since it can be educated by the rational soul. We are talking about the place of the soul where spontaneously felt emotions take place. (See Nicomachean Ethics). This makes one think of Plato’s irascible and concupiscible soul, however for Aristotle this soul, under the dominion of reason. gives life to moral virtues such as courage and temperance.