People frequently ask me what is the point of studying philosophy? My answer is always short. A few words suffice. The point of studying philosophy is learning to see. Once you get familiar with key philosophical doctrines, such as those put forward by Aristotle, you will understand the world better and make better decisions.
A good example of “learning to see” is the theory of the soul. The concept of the soul (“anima” in Latin) has been a central theme in philosophy and theology throughout history.
When people ask about the soul, they want to address key aspects of what it means to be human and what differentiates humans from dogs, cats, monkeys, and other animals. Humans have a soul. Animals and plants do not, or at least, not fully.
Origins of Aristotle’s theory of the soul
Aristotle did not invent the concept of the soul. The concept was already existing in older cultures such as those of ancient Egyptians and Hinduism. In those cultures, people believed that the soul was the animating energy or force behind life, also including human life.
For the ancient Egyptians and Hindus, the sole involved ideas of immortality, reincarnation, and the soul’s journey after death. Ancient Egyptians practised mummification of corpses to safeguard their soul in the afterlife. The mummy was meant to give the soul it a physical place of residence, so to speak.
In ancient Greece, a century before Aristotle, Pythagoras put forward that the soul was immortal and could migrate from one body to another. In this regard, Pythagoras was imitating the philosophy of Hinduism.
Aristotle devoted a full book to the concept of the soul. The Latin title of this work is “De Anima,” which means “About the Soul). Aristotle wrote this book when he was still a student of Plato’s or shortly after leaving Plato’s school.
Historians do not know the exact date of the writing, but it is clearly influenced by Plato’s theories. Aristotle had not yet developed his own philosophical system, or at least, not fully.
In this book, Aristotle categorizes the soul in three types or parts, namely, the vegetative soul, the sensitive soul, and the rational soul. Let us see what each type means. He devotes one part of “De Anima” to each typo of soul.
Aristotle’s vegetative and sensitive soul
First part, the vegetative or nutritive soul. According to Aristotle, this soul type is responsible for basic life functions and bodily systems such as growth and reproduction. Plants can be said to possess a vegetative soul in its simplest, most basic expression.
Second part, the sensitive soul. According to Aristotle, it enables perception, emotions, and desires. Those distinguish animals from plants. Animals possess both a vegetative soul and a sensitive soul. The latter enables animals to interact with the environment, respond to stimuli, and feel pleasure and pain.
The sensitive soul collects impressions through the sensory organs and their sensory modalities, namely, sight, hearing, touch, taste, and smell. Each sensory organ can detect specific qualities of objects. For example, the eye will perceive colour, shape, depth and distance. The ear will perceive sounds, etc.
In another article, I’ve explained that Aristotle’s metaphysics include the concept of identity (or unity, integrity, etc.) which designate the consistent aggregation of the characteristics of an individual.
When it comes to the sensitive soul, Aristotle employs the term “common sense,” referring to the capacity to integrate all sensory data from all different sense organs and arrive at single unified perceptions of the world. According to Aristotle, the “common sense” enables animals and humans to perceive the world in a coherent manner.
Aristotle regards imagination (“phantasia” in Greek) as part of the process of perception performed by the sensitive soul. He defines imagination as the faculty of the sensitive soul to retain and recall past sensory experiences. Actually, he should have used the term “memory” instead of “imagination.”
For what concerns the sensitive soul, Aristotle is referring to the most basic memory capacities, not to the rational ability to define universal concepts and develop creative ideas.
Aristotle’s theory of the rational soul
Third part, the rational soul, which is unique to humans. This soul type is the source of reason and morality. I would add that it is also the source of happiness because an individual cannot attain full happiness merely through a vegetative and sensitive soul.
The rational soul is unique to humans. Only humans can engage in rational thought, deliberation and reasoning. Thus, humans possess a vegetative soul, a sensitive soul, and a rational soul. Aristotle considers that each human being is a body-soul composite including elements of rational thought, or at least, of the potential to think rationally.
In a previous article, I’ve explained in detail how Aristotle’s metaphysics include the concept of potentiality and actuality. Those apply to every living creature. The refer to what the creature is like right now and what it can become in the future.
When it comes to the soul, Aristotle also employed the ideas of potentiality and actuality. He argues that the human soul has the potential of development. It can learn and cultivate new skills and capacities. It can turn its potential into actuality.
Active intellect in Aristotle’s theory of the soul
In his analysis of the rational soul, Aristotle distinguishes between “passive intellect” or “potential intellect” on the one hand, and “active intellect” or “agent intellect” on the other.
Passive intellect means the soul’s capacity to receive and process sensory inputs. It’s called “potential intellect” because it does not really add much to the sensory inputs. It represents the sensitive soul applied to humans.
In contrast, the active intellect is the capacity to engage in intellectual activity such as creating universal concepts and use them to draw rational arguments and conclusions.
Unfortunately, Aristotle then reverts to Plato’s philosophy. Instead of analysing how individuals can develop their active intellect or agency, Aristotle states that the active intellect is not an individual mental faculty, but a universal, shared faculty that all humans possess.
Just as Plato had been wrongly teaching, Aristotle restates that the universal intellect connects all individuals to a higher metaphysical reality, which is the source of all knowledge and rationality.
As we’ll see in upcoming articles, Aristotle eventually let go of the Platonic mystical conception of a universal intellect and began to analyse how each individual can develop his potential to achieve specific goals (self-actualization) and happiness.
The main difference between the passive and active intellect is that only the latter is able to go beyond sensory images and impressions, and extract from them universal, abstract truths that enable to make good decisions in the future.
Aristotle’s views on the immortality of the soul
The last part of “De Anima” is devoted to the immortality of the soul. In this part of the book, Aristotle argues against the concept of the soul’s immortality as presented by Pythagoras and Plato.
In contrast to Pythagoras and Plato, Aristotle maintains that the human soul is not immortal because it must be connected to a specific body.
Aristotle regards a soul as inseparable from an individual living body. The soul’s functions are linked to a physical body and cannot exist independently. Aristotle rejects the idea of the soul’s pre-existing birth or surviving death of the body.
The rejection of immortality is contradictory with Aristotle’s position on the “active intellect” as part of a mythical, higher realm which is shared with all humans.
In any case, Aristotle considers that the soul can only exist as part of a living soul-body relationship. He defines life as a state of being where the body is functioning in accordance to its nature.
According to Aristotle, death is the absence of functions and will stop the soul’s activity. Death is simply a lack of life, not a mythical state that the soul enters upon departing from a living body.
At the end of “De Anima,” Aristotle explains how each of us can develop our potential intellect or rationality. He states that intellectual skills are developed by teaching and learning, and moral virtues by habit and practice. I expand on this mater in my article about Aristotle’s “Nicomachean Ethics.”
If you are interested in developing your active intellect and cultivating happiness, I recommend you my book “Rationality is the way to happiness.”
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Aristotle’s views on ethics, virtue and happiness
Happiness and Aristotle’s theory of the soul
Aristotle’s concept of teleology