Philosophy 64 - 4.2.5 Aristotle

During the Middle Ages, people referred to Plato’s most famous pupil Aristotle as simply “the Philosopher.” This nickname is a testament to his enduring fame, as well as to the fact that he was driven by philosophical curiosity to try to understand everything under the sun. The first sentence of his famous work Metaphysics states, “Philosophy begins in wonder.” He exemplified this claim in his writing. His works ranged widely across all the main areas of philosophy, including logic, metaphysics, and ethics. In addition, he investigated natural philosophy, the fields of study that eventually gave rise to science. Aristotle also researched topics that would today be classified as biology and physics. Stylistically, his work was very different from that of his teacher. While Plato’s work was literary and even dramatic, Aristotle’s writings are presented as lecture.


Explore Aristotle’s ideas in greater depth in the chapters on metaphysics and epistemology.

Plato and his successors were prone to mysticism. It was easy to translate the philosophical theory of the forms into a mystical doctrine in which the forms were known by the mind of God. Aristotle resisted this trend. At the center of Aristotle’s work was his doctrine of the four causes. He believed that the nature of any single thing could be understood by answering four basic questions: “What’s it made of?” (material cause), “What shape does it have?” (formal cause), “What agent gave it this form?” (efficient cause), and, finally, “What is its end goal?” (final cause). Not only can we explain the nature of anything by answering these four basic questions, we can also understand the nature of the universe. Aristotle’s universe is a closed system that is comprehensible to humanity because it is composed of these four causes. Each cause leads to another, until we get to the first cause or prime mover at the head of it all. Somewhat obscurely, Aristotle claims that this first cause is “thought thinking itself.”

In addition to the doctrine of the four causes, it is important to understand Aristotle’s account of the soul. Unlike Plato, who held that the soul is an eternal substance that is reborn in various bodies, Aristotle has a functional conception of the soul. He defined the soul based upon what the soul does. In Aristotle’s understanding, all living things have souls. Plants have a vegetative soul that promotes growth and the exchange of nutrients. The animal soul, in addition to taking in nutrients and growing, experiences the world, desires things, and can move of its own volition. Added to these various functions in humans is the ability to reason.

Three panels, the first containing a sketch of a plant, the second a picture of a deer, and the third an outline of a human being.
Figure 4.5 Aristotle believed that all living beings had souls, but that the souls of various types of creatures differed in their abilities. The soul of a plant promotes growth and the exchange of nutrients. The animal soul allows for everything a plant can do, with the additional ability to desire things and move of its own volition. Only the human soul makes possible the ability to reason. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

With the four causes and the functional conception of the soul, we can begin to understand Aristotle’s ethics. Aristotle systematized Plato’s conception of ethics based upon his conception of the self and his four causes. Since everything that exists has a purpose, one of the basic questions for ethics is “What is the purpose of the human being?” After considering such candidates as pleasure and power, Aristotle settles on the answer “happiness” or, more accurately, “eudaimonia.” Rather than a fleeting emotional state, eudaimonia is better understood as “flourishing.” So the question at the heart of Aristotle’s ethics is “How should humans best achieve happiness?” His basic answer is that we achieve eudaimonia by cultivating the virtues. Virtues are habits of character that help us to decide what action is preferable in a particular moment. Cultivating these virtues will helps us to lead a fulfilling life.

It is generally true to say that Plato tended to be more focused on the transcendental world of the forms while Aristotle and his followers were more focused on this worldly existence. They shared a belief that the universe was comprehensible and that reason should serve as a guide to ordering our lives.


Aristotle’s virtue ethics are explored in much greater depth in the chapters on value theory and normative moral theories.

The content of this course has been taken from the free Philosophy textbook by Openstax