Aristotle was an ancient Greek philosopher born in Stagira, Macedonia (a city in Northern Greece) in 384 BC. At the age of 17, he moved to Athens to study philosophy with Plato at his Academy. Together, Aristotle, Plato, and Socrates (Plato’s teacher) are seen as the founders of the Western philosophical tradition. Aristotle is renowned for his knowledge on practically every subject known by the Greeks at the time including music, theater, science, ethics, biology, psychology, logic, metaphysics, poetry and more. In the middle ages, he would be referred to as “The Philosopher” and it is said that he was the last person to live who knew everything there was to know in his time. He believed that happiness was the goal of life and famously said that “Man is by nature a political animal.”

Aristotle studied philosophy at Plato’s Academy for 20 years. He then went to Asia, and on the island of Lesbos he studied hundreds of species of animals and fish. He developed an understanding of life as moving from the most simple to the most complex, known as the Great Chain of Being. Naturally, humans were at the top. He saw everything as having a nature which guides it’s actions, and found overwhelming evidence that the world has been intelligently designed. This is why “no animal has, at the same time, both tusks and horns.” He refers to God as the “unmoved mover.”

Aristotle would come to teach Alexander the Great before returning to Athens to found the Lyceum. Here, he would continue his biological studies as well as give lectures on philosophy. He became famous for pacing back and forth while talking, and for this reason his followers are called the peripatetics (“those who walk about”). Ultimately, like Socrates, he was charged with dishonoring the Gods, but unlike Socrates he chose to leave Athens, saying “I will not allow the Athenians to sin twice against philosophy.”

Aristotle created a system of logic which lasted until the 19th century. Before Aristotle, there were two ways of evaluating arguments. The first was done by the sophists, teachers of rhetoric, who believed the most important thing was for an argument to be persuasive i.e. sound good. In response to this, Socrates developed his own method (the Socratic Method) where he would use a series of questions to show others the wholes in their beliefs. What Aristotle did is he created a set of rules and a method for showing whether the conclusions of an argument actually follow from its premises i.e. formal logic. For example, he demonstrates what is known as a syllogism: if all As are Bs, and all Bs are Cs, then all As must be Cs. Thus, if all men are mortal, and Socrates is a man, it can be logically concluded that Socrates is a man.

Aristotle recognized the importance of being clear when making a statement, seeing many of the philosophical puzzles of his time being the result of a confusion of terms. For example, Zeno of Elea famously presented the paradox of a runner on a track. Zeno explains that because every distance can be infinitely divided into smaller distances, and because the sum of these infinite small distances would therefore be infinite, its impossible for the runner to complete the length of the track in a finite period of time. Aristotle explains that while the track can be potentially divided infinitely, in actuality it’s not. The track is a finite length. In this way, Aristotle dissolves the paradox.

Like Plato, he believed everything has a form. However, Plato’s Theory of Forms claimed there to be Forms, such as Beauty or Justice, that exist in a higher realm i.e. the realm of the Forms (or Ideas). Aristotle would disagree with Plato on this point, which is the foundation of Platonic philosophy. He saw the form not existing apart from the object, but rather a part of it. Everything in the world has both matter and form.

Likewise, Plato believed that the philosopher was someone who could recognize the Forms and this allowed them to understand the world. For Aristotle, the philosopher was someone who through his experience of the world, recognized the forms that things take. This difference would develop in modern times into the schools of rationalism (the belief that knowledge comes from reason) and empiricism (the belief that knowledge comes from experience). Aristotle believed just as much in the importance of reason as Plato, but he complemented Plato’s deductive method (using general principles to understand particular things) with an inductive process (using specific things to determine general principles). For Aristotle, knowledge is attained through experience, inducted and abstracted, and ultimately recognized by the intuition as being true. This has served as the foundation of the scientific method every since.

Aristotle understood metaphysics as the first principles for explaining reality. He recognized that everything has four causes: material, formal, efficient and final. The material cause is the material which it is made of (ex: wood), the formal cause it how it is arranged (four legs and a top), the efficient cause is what caused it to exist (a carpenter), and the final cause is it’s ultimate purpose (to be a table).

Science (i.e. physics) is then the second principles for understanding the things of the natural world. In ancient Greece, four primary elements had been recognized to exist: earth, water, air and fire. Aristotle embraced this understanding of the world, and added aether as a fifth element to explain the nature of the stars and planets. Aristotle’s father had been a physician, and Aristotle also adopted the belief that the natural world could be explained in terms of the opposites hot and cold, and wet and dry.

Aristotle recognized that living things, in addition to bodies, also have a soul. For Aristotle, a plant has a vegetative soul. Animals also have a vegetative soul. Animals also have a vegetative soul, but additionally they also have a sensitive soul. Humans have both the vegetative soul and sensitive soul, and a unique third soul which he called the rational soul. It is the rational soul which allows humans to live a virtuous life.

Aristotle believed that the goal of life was happiness. Through the rational soul, a human develops intellectual virtues, such as contemplation, which enable him to rise above other living things. In his Nicomachean Ethics (named after his son Nicomachus), Aristotle emphasizes the importance of developing good moral character. This can be done by avoiding excesses, what is known as the doctrine of the mean. For example, someone who is courageous is neither too rash nor a coward. Because humans have free will, they are able to do what is right. Aristotle valued friendship, seeing a friend as someone who allows the individual to cultivate his higher self. He also believed that a woman’s happiness is just as important as a man’s, and therefore believed that a repressive city like Sparta to be incapable of attaining complete happiness.

For Aristotle, character was just as important to the state as it is the individual. Politics is an extension of ethics. The ideal government is the one run by those with the best character, who act in the best interest of their citizens. Problems arise when those with bad character become rulers, as for example, when a kingship becomes a tyranny. For Aristotle, laws are reflective of a moral ideal, but they need to be flexible in order to adapt to changing circumstances.

Aristotle recognized the importance of organizations for human beings. He saw that human naturally come together to create families, villages and states. For this reason, he famously says that “Man is by nature a political animal.” While in an ideal world, those who are best would be rewarded, and those who aren’t would not (what he called distributive justice), in the real world this type of justice must be tempered by the concern that everyone is taken care of (i.e. corrective justice). Unfortunately, Aristotle did not extend this principle to slaves, who he saw as the property of their masters.

Aristotle’s teachings included not only the theoretical sciences (math, physics and metaphysics) and practical sciences (ethics and politics), but also what he referred to as the productive sciences (things like music, poetry, theater and medicine). He saw art as imitating life. Tragedy allows people an outlet to release their emotions (known as catharsis). Comedy allows people to laugh at themselves. Art can transcend history (i.e. what’s happened), inspired by what can be.

Aristotle’s learning was extraordinary, as are his writings. Like Plato, he would greatly influence medieval philosophy, coming to be known as simply “The Philosopher.” His understanding of God as an “unmoved mover,” that the world as intelligently designed, and that the earth is the center of the universe would be embraced by Christianity. Aristotelianism also influenced developments in Jewish and Islamic philosophy, and Islamic philosophers such as Averroes, Avicenna, and al-Farabi considered his philosophy to be on the same level as the teachings of the prophets. Like Plato, it would be difficult to find a modern Western philosopher who has not been influenced by his thoughts in some way.