If there is one thinker most responsible for the development of the Western philosophical canon, it is Aristotle. He thought and wrote in virtually every branch of philosophy and is cited more times than any other philosopher in the major philosophical encyclopedias. Although it may be said that modern philosophy has progressed past many of his ideas, Aristotle set into motion the major areas of inquiry that constitute the discipline today.
While little is known about Aristotle’s life, we do have a basic biographical picture. Aristotle was born in Northern Greece in the city of Stagira in 384 BCE. His father Nicomachus was a physician who tended to the Macedonian King Amyntas. Both Nicomachus and Aristotle’s mother died when Aristotle was 13 and for the next four years Aristotle was cared for by his guardian Proxenus of Atarneus. At 17 years old, Aristotle joined Plato’s Academy and spent 20 years studying under Plato. He then travelled abroad, first to the court of Hermias of Atarneus, and, after Hermias died, to the island of Lesbos to research plant and animal biology. In Lesbos, Aristotle married a woman named Pythias, herself a biologist. They had a daughter together and named her Pythias the younger.
In 343 BCE, Aristotle relocated to Macedon at the behest of King Philip II to tutor Philip’s son Alexander — or, as he was later known, Alexander the Great. Aristotle, himself a cultural elitist, encouraged Alexander to deal with the “barbarians” in the East as “beasts or plants” and conquer them all. Aristotle remained Alexander’s tutor for eight years until he returned to Athens in 335 BCE and established his own school, the Lyceum. During this time, Aristotle’s wife Pythias died and he became involved with a woman named Herpyllis. Together, they had a son named Nicomachus named after Aristotle’s father.
Aristotle taught and wrote at the Lyceum for a number of years before fleeing Athens in 322 BCE following the death of Alexander the Great and the subsequent rise of anti-Macedonian sentiment. Upon his departure, Aristotle famously announced that he “saw no reason to permit Athens to sin twice against philosophy” — a reference to the Athenian trial and execution of Socrates. Aristotle passed away later that year at his mother’s family estate on the Greek island of Euboea.
Unfortunately, all of Aristotle’s literary writings, which the Roman statesman and writer Cicero once called “a river of gold,” were lost. All that remain are his unpublished lecture notes. Though dry in style, these notes managed to achieve a revolution in human thought.
Chiefly known as a philosopher, Aristotle was also an accomplished biologist. He pioneered the scientific method by gathering and classifying large amounts of plant and animal data to draw empirical conclusions about biological trends, including the relationship between adult body size and litter (larger size = fewer offspring). He also anticipated Darwin’s theory of evolution by documenting that “an animal’s structure is well matched to function. Aristotle’s taxonomy extended beyond plant and animal specimens to philosophy itself, which he divided into three branches of inquiry, or “sciences”:
- Theoretical science, which aims at contemplation for its own sake. Examples include mathematics, physics, and metaphysics.
- Practical science, which aims at doing good. Examples include ethics and politics.
- Productive science, which aims at creating beautiful or useful objects. Examples include trades, crafts, arts, and rhetoric.
Having classified the major branches of inquiry, Aristotle next established the correct methods of inquiring. To test the validity of simple arguments, Aristotle devised the earliest known system of formal logic in the West. Of particular note is his development of the syllogism: a three-part proposition consisting of a major premise, a minor premise, and a conclusion:
- If all As are Bs (major premise) and all Bs are Cs (minor premise), then all As are Cs (conclusion). For example, if all humans are mammals, and all mammals are animals, all humans are animals.
The syllogism is used to determine the soundness or fallaciousness of an argument by examining whether its premises justify its conclusion. In this sense, syllogisms are what Aristotle called “demonstrated” knowledge, providing a useful check on whether a mistake has been made in one’s reasoning.
Ultimately, Aristotle believed that all demonstrated knowledge relies on undemonstrated “first” principles that are intuitively true yet technically unprovable. In logic, these first principles include:
- The law of identity (A = A).
- The law of non-contradiction (not both A and not A).
- The law of excluded middle (either A or not A).
For all of its powers, Aristotle acknowledged that logic is not an all-encompassing solution. When proceeding from complex matters that cannot be broken down to a syllogism, Aristotle believed that we must consult the endoxa, or the received wisdom from the past, as the starting point of the investigation. He also affirmed the value of phainomena, or what appears to us through our senses. In this respect, Aristotle breaks with Plato, who held that the senses are deceptive and worthy of distrust. Plato considered the intellect the sole means of attaining knowledge of essences that are allegedly located in an unseen world of forms. Aristotle, on the contrary, believed that humans attain such knowledge by studying the visible world around them. This is the reasoning behind Aristotle’s theory of the Four Causes, or the four ways of “knowing” hylomorphic substances, i.e. substances composed of both matter and form. These four causes are:
- The material cause, or what a substance is made of.
- The formal cause, or how the substance is structured.
- The efficient cause, or what brought the substance into existence.
- The final cause, or the purpose of a substance.
Take the example of a wooden house. Its material cause is the wood from which it is made. Its formal cause is its shape as a house rather than a chair, a desk, a cutting board, etc. Its efficient cause is the carpenter who built it. And its final cause is to shelter its inhabitants. With this four-cause framework, one grasps the essential house-ness of the house, which Aristotle asserts inheres in the house itself rather than in a perfect house-form located in some posited world inaccessible to the senses.
Moving to practical science, Aristotle offered a thoroughgoing theory of ethics. He began with teleology, or the belief that all things have an aim or function. For living things, function is determined by the type of soul a being possesses. It should be mentioned that Aristotle’s Greek term for soul is psyche and is better thought of as consciousness than an eternal individual spirit. Indeed, Aristotle believed that the soul cannot exist without a body and perishes upon a being’s physical death. In any case, Aristotle, again employing taxonomy, created a hierarchy of living beings — or psyches — grounded in his understanding of their functions:
- Plants (vegetative souls), whose functions are limited to nutrifying and growth.
- Animals (sensitive souls), whose functions, in addition to those of plants, include desire and motion.
- Humans (rational souls), whose functions, in addition to those of plants and animals, include reasoning.
Aristotle advanced an ethical system grounded in virtue, or excellence of character. Virtue consists in carrying out a function well. Because humans are unique among animals in possessing reason, Aristotle maintained that our function is to exercise our reason, specifically to promote eudaimonia, or human flourishing. Ever the taxonomist, Aristotle identified two broad categories of virtue:
1) Intellectual virtue, which facilitates learning, deliberation, and judgment to determine the best course of action among an array of options.
2) Ethical virtue, which supplies the will to carry out the actions one has determined to be best.
While intellectual virtue is acquired naturally through instruction, ethical virtue requires practice to overcome akrasia, or weakness of the will. Aristotle warned that it takes time to develop good habits and that practicing ethical virtue is initially an arduous process. Overtime, however, and with diligent effort, one may cultivate a natural inclination toward virtuous action. It is only at this point, wherein one “takes pleasure and pain in the right things,” that one becomes truly virtuous.
Aristotle provided the heuristic of the “golden mean,” or the midway point between the extremes of deficiency and excess, to help guide our actions. One among Aristotle’s examples is the case of bravery: when considering how to respond to danger, one should neither act cowardly (which is a deficiency of bravery) nor recklessly (which is an excess of bravery) but courageously (which is the golden mean of bravery). As a sidebar, Aristotle acknowledged that while virtue is necessary to achieve eudaimonia, it is not sufficient; for that, a degree of good fortune, to secure basic necessities such as food, water, shelter, health, and safety, is also required.
Aristotle’s virtue ethics serve as the groundwork for his envisioned prosperous city, or polis. Aristotle regards human beings as intrinsically social animals that require a group setting to be happy and productive. But it is not enough to merely cohabitate; the citizens of a polis must exercise good will toward one another and take pleasure in one another’s successes. To this end, Aristotle advocates an aristocratic city, or a city governed by the most excellent citizens, to ensure that the city’s education system and laws encourage the right types of behaviors. These efforts aim not only at social cohesion but also economic justice, including an equitable distribution of resources and the treatment of goods as ends in themselves (i.e. used to promote well-being) rather than a means to an end (i.e. exploited for profit).
Now, while this ethical and political philosophy may be intriguing, it is ultimately useless unless enough people agree to live by its tenets. This is where the productive sciences of rhetoric and tragedy enter the scene. Aristotle recognized that humans are persuaded by certain types of rhetorical appeals and set out to document them. He identifies three components of persuasive speech:
- Logos, or the actual content of the speech.
- Pathos, or the emotion the speaker conjures in the audience.
- Ethos, or the impression of the speaker’s character the speaker instills in the audience.
All three are said to be crucial to effective persuasion. It is not enough for the speaker to provide an intellectually convincing account of their argument; they must also tap into the audience’s feelings and earn the audience’s trust. It is only by uniting these three appeals that rhetoric achieves its full potential.
In addition to straightforward speeches, Aristotle affirms the value of literary disciplines such as tragedy and poetry to persuade people. He advocates didacticism, or the aesthetic philosophy that art should be used to teach about life. Tragedy is said to depict character flaws and base behavior in order to provide the audience with catharsis, or a purging of dangerous passions. Poetry, according to Aristotle, enlightens people to the possibilities of the future and broadens the audience’s perspective by making them aware of the universal aspects of the human experience. The arts, due to their aesthetic appeal, are said to be uniquely suited to the task of imparting valuable lessons to people and thus play an important role in Aristotle’s ethical project.
Following Aristotle’s passing, the Peripatetics movement was founded to spread his philosophy. In the Middle Ages, Muslim scholars translated Aristotle’s works into Arabic while Roman scholars translated them into Latin. Later, theologians such as Thomas Aquinas began interpreting religious texts through the lens of Aristotle’s philosophy. Indeed, Aristotle’s argument for the necessity of an “unmoved mover” (to avoid the problem of infinite regression) was adapted by Aquinas in his “first cause” argument for God’s existence. Today, there is renewed interest in aspects of Aristotle’s philosophy, particularly his virtue ethics and how they may be used to circumvent the problem of moral relativism by grounding morality in a universal good character. Aristotle remains essential reading for all students of philosophy as the progenitor of the modern discipline.