1.3: Greek Philosophy

Perhaps the single greatest achievement of Greek thought was in philosophy. It was in philosophy that the Greeks most radically broke with supernatural explanations for life and thought and instead sought to establish moral and ethical codes, investigate political theory, and understand human motivations all in terms of the human mind and human capacities…. [T[he word “philosophy” literally means “love of knowledge,” and Greek philosophers did much more than just contemplate the meaning of life; they were often mathematicians, physicists, and literary critics as well as “philosophers” in the sense that that the word is used in the present….

Building on the discoveries and knowledge of civilizations in Egypt and Mesopotamia, among others, the Ancient Greeks developed a sophisticated philosophical and scientific culture. One of the key points of Ancient Greek philosophy was the role of reason and inquiry. It emphasized logic and championed the idea of impartial, rational observation of the natural world.

The Greeks made major contributions to math and science. We owe our basic ideas about geometry and the concept of mathematical proofs to ancient Greek mathematicians such as Pythagoras, Euclid, and Archimedes. Some of the first astronomical models were developed by Ancient Greeks trying to describe planetary movement, the Earth’s axis, and the heliocentric system—a model that places the Sun at the center of the solar system. Hippocrates, another ancient Greek, is the most famous physician in antiquity. He established a medical school, wrote many medical treatises, and is— because of his systematic and empirical investigation of diseases and remedies—credited with being the founder of modern medicine. The Hippocratic oath, a medical standard for doctors, is named after him.

The men who became the most famous Greek philosophers of all time … were a three-person line of teachers and students. Socrates (469 – 399 BCE) taught Plato (428 – 347 BCE), who taught Aristotle (384 – 322 BCE), who went on to be the personal tutor of Alexander the Great for a time. It is one of the most remarkable intellectual lineages in history – three of the greatest thinkers of Greek civilization and one of the greatest military and political leaders, all linked together as teachers and students.


Socrates never wrote anything down; like most of his contemporaries, he believed that writing destroyed the memory and undermined meaning, preferring spoken discourses and memorization. Instead, his beliefs and arguments were recorded by his student Plato, who committed them to prose despite sharing Socrates’ disdain for the written word. Socrates challenged the sophists[1] and insisted that there are essential truths about morality and ethical conduct, but that to arrive at those truths one must be willing to relentlessly question oneself. He took issue with the fact that the sophists were largely unconcerned with ethical behavior, focusing entirely on worldly success; according to Socrates, there were higher truths and meanings to human conduct than mere wealth and political power.

Socrates used what later became known as the “socratic method” to seek out these fixed, unchanging rules of truth and ethics. In the socratic method, the teacher asks a series of questions of the student, forcing the student to examine her own biases and gaps in logic, until finally arriving at a more satisfying and reasonable belief than she started with. In Socrates’s case, his questions were meant to lead his interlocutors to arrive at real, stable truths about justice, truth, and virtuous politics. Unlike with the sophists’ mastery of rhetoric, the point of the question-and-answer sessions was not to prove that nothing was true, but instead to force one to arrive at truths through the most rigorous application of human reason.

A Roman copy of an original Greek bust of Socrates – as with many Greek sculptures, only the Roman copy survives. Most Greek statues were made of bronze, and over the centuries almost all were melted down for the metal.


Plato agreed with his teacher that there are essential truths, but he went further: because the senses can be deceived and because our insight is imperfect, only through the most serious contemplation and discussion can we arrive at truth. Truth could only be apprehended with the mind, not with the eye or ear, and it required rigorous discussion and contemplation. To Plato, ideas (which he called “Forms”) were more “real” than actual objects. The idea of a table, for instance, is fixed, permanent, and invulnerable, while “real” tables are fragile, flawed, and impermanent (this is thus his metaphysics). Plato claimed that politics and ethics were like this as well, with the Form of Justice superseding “real” laws and courts, but existing in the intellectual realm as something philosophers ought to contemplate.

In Plato’s work The Republic he wrote of an imaginary polis in which political leaders were raised from childhood to become “philosopher-kings,” combining practical knowledge with a deep understanding of intellectual concepts. Plato believed that the education of a future leader was of paramount importance, perhaps even more important than that leader’s skill in leading armies. Of all his ideas, this concept of a philosopher-king was one of the most influential; various kings, emperors, and generals influenced by Greek philosophy would try to model their rule on Plato’s concepts right up to the modern era.

Plato founded a school, the Academy, in Athens, which remained in existence until the early Middle Ages as one of the greatest centers of thought in the world. Philosophers would travel from across the Greek world to learn and debate at the Academy, and it was a mark of tremendous intellectual prestige to study there. It prospered through the entire period of Classical Greece, the Hellenistic Age that followed, and the Roman Empire, only to be disbanded by the Byzantine (eastern Roman) emperor Justinian in the sixth century CE. It was, in short, both one of the most significant and one of the longest-lasting schools in history.

Plato’s most gifted student was Aristotle, who founded his own institution of learning, the Lyceum, after he was passed over to lead the Academy following Plato’s death. Aristotle broke sharply with his teacher over the essential doctrine of his teaching. Aristotle argued that the senses, while imperfect, are still reliable enough to provide genuine insights into the working of the world, and furthermore that the duty of the philosopher was to try to understand the world in as great detail as possible. One of his major areas of focus was analysis of the real-life politics of the polis; his conclusion was that humans are “political animals” and that it was possible to improve politics through human understanding and invention, not just contemplation.


Aristotle was the ancient world’s greatest intellectual overachiever. He single-handedly founded the disciplines of biology, literary criticism, political science, and logical philosophy. He wrote about everything from physics to astronomy and from mathematics to drama. His work was so influential that philosophers continued to believe in the essential validity of his findings well into the period of the Renaissance (thousands of years later) even though many of his scientific conclusions turned out to be factually inaccurate. Despite those inaccuracies, he unquestionably deserves to be remembered as one of the greatest thinkers of all time.

Aristotle’s system of logic was not only the first developed in the West, it was considered complete and authoritative for well over 2000 years. The core of Aristotle’s logic is the systematic treatment of categorical syllogisms:

  1. All monkeys are primates.
  2. All primates are mammals.
  3. So, all monkeys are mammals.

This argument is a categorical syllogism. That’s a rather antiquated way of saying it’s a two premise argument that uses simple categorical claims. Simple categorical claims come in one of the following four forms:

  • All A are B
  • All A are not B
  • Some A are B
  • Some A are not B

There are a limited number of two premise argument forms that can be generated from combinations of claims having one of these four forms. Aristotle systematically identified all of them, offered proofs of the valid one’s, and demonstrations of the invalidity of the others. Beyond this, Aristotle proves a number of interesting things about his system of syllogistic logic and he offers an analysis of syllogisms involving claims about what is necessarily the case as well.

While Aristotle was a student of Plato’s, his metaphysics is decidedly anti-Platonist. The material of the world takes various forms. Here it constitutes a tree and there a rock. The things constituted of matter have various properties. The tree is a certain shape and height, the rock has a certain mass. Plato accounts for the various forms matter takes and the ways things are in terms of their participating in abstract and ideal forms to one degree or another. Plato’s metaphysics centrally features an abstract realm of eternal unchanging and ideal forms. Plato’s forms are not themselves part of the physical spatio-temporal world. Aristotle rejects the theory of abstract forms and takes everything that exists to be part of the physical spatio-temporal world. It might thus be tempting to think of Aristotle as a materialist, one who thinks all that exists is matter, just atoms swirling in the void. Some pre-Socratic philosophers could accurately be described as materialists. But this would miss key elements of Aristotle’s metaphysics. While Aristotle denies the existence of an abstract realm of eternal and unchanging ideal entities, his account of the nature of things includes more than just matter. Aristotle holds the view that form is an integral part of things in the physical world. A thing like a rock or a tree is a composite of both matter and form. In addition to matter, the way matter is gets included in Aristotle’s metaphysics.

View the following videos (students might be prompted to log in with their MY FM credentials at the Library Multimedia Resource Page to access them):

Plato and Aristotle’s Differences

Aristotle Films on Demand Clips (See clips # 13- # 15 for more information specifically about Aristotle)

  1. Some of the early philosophers of the Greek classical age were the Sophists: traveling teachers who tutored students on all aspects of thought. While they did not represented a truly unified body of thought, the one common sophistic doctrine was that all human beliefs and customs were just habits of a society, that there were no absolute truths, and that it was thus vitally important for an educated man to be able to argue both sides of an issue with equal skill and rhetorical ability. Their focus was on training elite Greeks to be successful – the Greek term for “virtue” was synonymous with “success.” Thus, the sophists were in the business of educating Greeks to be more successful, especially in the law courts and the public assemblies. They did not have a shared philosophical doctrine besides this idea that truth was relative and that the focus in life ought to be on individual achievement.