Understanding the Duality of Human Existence

Humans: Theory of the Soul

Both philosophers believe in the duality of human beings. While for Plato, the human meaning is an accidental union between body and soul, for Aristotle, these two elements make up a substantial unity, where the body is matter and the soul is the form (Hilemorphism: man is the unit substantially).

Plato's Perspective

For Plato, the soul is the perfection that belongs to the world of ideas and possesses true knowledge. It has three parts: the rational (Auriga), the irascible (white horse), and the concupiscent (black horse). These three parts are explained in the myth of the winged chariot: when the soul loses control of the other parts, it is represented as a chariot that inhabits the world of ideas. In the world, it falls and forgets sensitive ideas and knowledge. To restore it, one must simply remember (Platonic reminiscence).

Aristotle's View

Aristotle, as his teacher, also believes in the duality of human beings, but unlike Plato, he believes that the soul is the principle of life and movement in a living body. The soul cannot exist separately from the body; it is the realization of the body, and its actualization is inseparable from it. The only part of the soul that is separated from the body is the intellect. Only this part of the soul is immortal; the other parts are not. This understanding leads to the distinction between the divine and immortal aspects of the soul, which currently represent the abstract forms of things.

Types of Soul According to Aristotle

• Vegetative: Performs the functions of growth, nutrition, and reproduction.
• Sensory: Regulates the nervous system.
• Rational: The ability to think and understand; uniquely human.

Epicurus

Epicurus defends a materialist physics contained in the atomism of Democritus. He posits that the universe consists of atoms and void. The atoms move vertically but have the ability to deviate from their initial trajectory (declinatio), encounter each other, and create substances. Clashes occur by chance, without a cause that determines them, which aligns with the concept of freedom in the universe.

Stoicism

Stoicism advocates for a naturalistic ethics. A person is viewed as a microcosm, and their conduct is governed by reason. Hence, happiness is achieved by acting in accordance with nature and reason. The ideal of the wise is autodomini, the control of passions, leading to a calm state of mind (Apatheia) in one's ascetic life.

St. Thomas Aquinas

St. Thomas follows a certain trend of Platonism; his metaphysics is governed by the idea of participation, according to which finite beings are composed of essence, which includes the subject and the manner of Aristotle, and existence. The more involved their existence is, the more perfect they become. Being simple and infinite, God is the creator and final cause of all finite beings and is the only entity that possesses its own existence, which is absolutely perfect.