It's no small feat to be revered worldwide, but a person's accomplishments are even more incredible when their influence extends to even thousands of years later. As such, there are only a small number of people who could boast this if they were alive to do so but many of them are the philosophers of ancient Greece.
Although historical research has shown that they took more inspiration from other cultures than it seemed at the time, it's nonetheless undeniable that they've had a significant impact on how people thought and how they understood the world.
Socrates (The Socratic Method)
Socrates is considered the father of western philosophy and was known to encourage critical thinking in his students. Part of this came from extolling the importance of examining one's life and knowing the limits of one's wisdom.
But as National Geographic outlined, an aspect of his influence that still shines through today is the Socratic method. This is a teaching style that de-emphasized dictating what is true to students in favor of asking them a series of thought-provoking questions to let them arrive at the answers themselves.
Plato (The Branches of Philosophy)
It is only through Plato's writings that anyone has any access to the wisdom of his Socrates. However, Plato's own contributions to philosophy are as vast and fundamental as his teacher's.
According to National Geographic, he developed some of the world's most essential categories of philosophy, such as ethics, aesthetics, metaphysics, and epistemology. The last category concerns the study of knowledge itself and what distinguishes knowledge from opinion.
Aristotle (Political Theory, Zoology)
According to the Stanford Encyclopedia of Philosophy, Aristotle influenced centuries of philosophical thought by building on Plato's ideas of epistemology, ethics, logic, aesthetics, and metaphysics.
And he also made his own contributions to the philosophical canon by developing intricate (at least for the time) political theories. He also pioneered the field of zoology while exploring his deep fascination with the natural world and describing the plants and animals he observed in great detail.
Pythagoras (The Pythagorean Theorem)
Anyone who remembers their math classes growing up will likely recall Pythagoras's method for determining the square of a right triangle's hypotenuse. But that only scratches the surface of Pythoragoras' influence on the worlds of philosophy and mathematics.
According to Washington State University's website, he was among the first to envision the universe as being understandable and structured due to its mathematical order. Just as music can be broken down mathematically, Pythagoras saw that truth as applying to existence itself.
Epicurus (Materialism)
In a radical departure from other philosophers of his time, Epicurus argued against the immortality of the soul and believed that only that which can be materially observed can be confirmed to exist.
The Oxford Handbook of Epicurus and Epicureanism noted this view of materialism has earned Epicurus his share of opponents both during his life and since. But it also inspired enough followers to form the foundation for an entire school of philosophy that persisted for centuries.
Plutarch (Historiography, Biography)
Although Plutarch was indeed a philosopher, he's perhaps proved more influential as a biographer and historical writer and has influenced how people tell stories of each other's lives.
According to the Smithsonian Magazine, Plutarch's bias and his often anecdotal approach to history have inspired significant criticisms in retrospect, but the idea of chronicling history through biography at all can be traced back to him.
Thales (Philosophy in general)
If Socrates is considered the father of western philosophy, Thales of Miletus is largely credited for being the father of philosophy at large.
According to the Stanford Encyclopedia of Philosophy, Aristotle credited Thales for being the first to question the natural world's "causes and principles," which was both the basis for philosophy and the life's work of each famous philosopher that followed, including Socrates.
Xenophon (Political Philosophy)
Xenophon was recognized as an astute historian and a capable soldier, but he was also a pioneering figure in political philosophy and is one of the only people besides Plato to write firsthand chronicles of Socrates's teachings.
And according to a 2011 article in the Bryn Mawr Classic Review journal, Xenophon was well-known for making sophisticated historical arguments about what made an ideal leader in terms of ethics, governmental models, and political strategy. Although he valued tradition, he also saw it as a necessity for philosophers to have room to clash with those traditions.
Porphyry (Neoplatonism)
According to the Stanford Encyclopedia of Philosophy, Porphyry achieved much of his renown by applying a modified version of Plato's philosophy to Pagan religions and other then-underexplored phenomena in the world at the time.
His status as a prominent Neoplatonist was also borne from his attempts to harmonize Platonism with Aristotle's writings on logic. He also introduced the concept of unifying the concept of the soul that was traditionally divided between the intelligent soul and the "lower soul," which includes the body's senses.
Zeno of Citium (Stoicism)
Although Zeno of Citium's personality fit the quiet, reserved mental image that people typically have when they describe someone as "stoic," that had less to do with the basis of the philosophy he invented than it seems.
According to Berkeley City College philosophy professor Eric Gerlach, stoicism centers around a cosmically optimistic belief that the universe is fundamentally good and is fated to preserve what is good and destroy what is fundamentally harmful. As such, Zeno's followers believed in accepting one's fate without fear.
Diogenes (Cynicism)
According to the University of Chicago-affiliated website LacusCurtius, Diogenes is widely considered the founder of the philosophy of cynicism. He's perhaps most famous for an anecdote that saw him wander the streets with a lantern in broad daylight in search of an honest man.
Regardless of the modern connotations of the word, the cynicism that Diogenes pioneered emphasized living as simply and self-sufficiently as possible without shame or worry about what others think. Since a person's responsibilities and circumstances can change suddenly at any time, cynics like Diogenes prized living in a way that best adapts to those changes.
Aristarchus of Samos (Heliocentrism)
When people reference the historical fight to recognize that the Earth and the other planets in the solar system revolve around the sun, they tend to describe Copernicus or Galileo for pioneering that concept.
However, the first model to suggest this came almost 2,000 years before either of them and was proposed by Aristarchus of Samos. According to the National Center for Atmospheric Research, his philosophy was intertwined with mathematics, but he had a particular focus on matters of astronomy.
Democritus (Atomism)
Although the importance Democritus placed in the value of cheerfulness earned him the nickname "the laughing philosopher," he would make a serious and incredibly influential contribution to humanity's understanding of the world as one of the earliest founders of the atomic theory.
The nuances of how atoms work would be fleshed out by scientists over the course of centuries, but Democritus was among the first to propose that all matter had an atomic basis.
Heraclitus (Metaphysics)
Often called "the weeping philosopher" due to his melancholic personality or "the obscure" due to his cryptic way of speaking, Heraclitus made his mark with the unique way he saw the universe, which had a significant role in inspiring Plato's philosophy.
According to S. Marc Cohen from the University of Washington, Heraclitus broke from the views of early philosophers like Thales by asserting that the world was in a state of constant change and that permanence was essentially an illusion. Before him, it was commonly understood that reality was fixed and permanent, which made change difficult to explain.
Protagoras (The Sophist School, Relativism)
Protagoras made his name as one of ancient Greece's most important sophists, which means that he specialized in developing argumentative techniques for intellectual debates.
But while he had a keen aptitude for how to effectively express one's philosophy, he was also a firebrand thinker in his own right. His assertion that "man is the measure of all things" is considered one of history's first relativist arguments.
Pyrrho (Skepticism)
As Berkeley City College philosophy professor Eric Gerlach explained, Pyrrho is arguably considered Greece's greatest skeptic. And what that means is that his philosophy was based on the idea that the search for knowledge and the process of inquiring into what is true is never-ending.
A similar ethos is common in modern science as it's generally understood that there's always more to discover and that anyone claiming to have achieved universally true knowledge is typically looking at the world with an incomplete lens.
Zeno of Elea (Paradoxes)
Although many ancient Greek philosophers had ideas that inspired future generations, Zeno of Elea's famous paradoxes that sought to argue against the concepts of change, motion, and plurality are more influential for what other philosophers accomplished by disagreeing with them.
According to the Stanford Encyclopedia of Philosophy, Aristotle presented some of the only surviving records of Zeno's arguments to try and refute them. Additionally, an argument meant to highlight the absurdity of "complete divisibility" inadvertently convinced atomist philosophers that "indivisible" atoms exist.
Parmenides (Arguments against change)
As S. Marc Cohen from the University of Washington, Parmenides's views presented a turning point in the history of philosophy because it introduced a new, controversial perspective in a major debate waged before Socrates rose to prominence.
While Presocratic philosophers argued over whether change was the only reality in life or just a part of an otherwise permanent system, Parmenides outright stated that change is impossible. This claim and the arguments supporting it inspire a wide array of interpretations and debates even today, as Parmenides's words are considered some of the most mysterious among ancient Greek philosophers.
Empedocles (The four elements)
As Nicos I. Georgakellos wrote in Empedocles of Acragas: His Theory and the Exact Sciences, Empedocles was responsible for some of the earliest scientific theories in Greek philosophy and conceptualized the four elements (fire, water, earth, and air) that were supposed to form the building blocks for all matter.
Although this view of the world is understandably considered primitive today, Georgakellos pointed out that Empedocles was closer to the truth than researchers who lived almost 2,000 years later in the 17h and 18th centuries.
Timon of Phlius (Expanding and preserving skepticism)
According to the Stanford Encyclopedia of Philosophy, Timon of Phlius was the leading disciple of Pyrrho and the one responsible for any record of the father of skepticism's philosophies existing because Phyrrho never wrote anything.
In addition to preserving his teacher's skeptical views, he argued for their validity in a series of satirical depictions of other philosophers he considered lesser. Timon also expanded Pyrrho's philosophical framework into matters his teacher never commented on and explained why skepticism isn't a rejection of life as his critics often claimed.
Xenophanes (Theology, Satire)
As Herbert S. Long of Case Western Reserve University wrote, so many of Xenophanes's philosophical statements concern the nature of God (or gods, in his case) that Aristotle and future philosophers considered him more of a theologian than a natural philosopher.
Nonetheless, he made his mark by conceptualizing Greek gods as beings that embody the best aspects of humanity, contrasting from the more flawed depictions of them seen in Homer's works. He used the idealistic framework as a foundation for his belief that humans should abandon war and similar strife to resemble these qualities better. Xenophanes made his points in poems that included some of history's first satirical works.
Anaxagoras (Scientific theories)
Anaxagoras was the first of the Greek philosophers to settle in Athens, but his influence extended beyond establishing a future hotbed of philosophical thought. He is famous for envisioning the world as "everything within everything," meaning that everything in the universe is connected through mixtures of the same basic ingredients.
The Smithsonian Magazine reported that Anaxagoras was ahead of his time in some significant ways as he was exiled for understanding that the Moon is a rocky mass with no light of its own, rather than a god. This also allowed him to correctly explain how eclipses work before anyone else.
Chrysippus (Logic, Stoicism)
As Berkeley City College philosophy professor Eric Gerlach explained, Chrysippus is considered the "second father" of stoicism because he fleshed out the principles of his forebears, like Zeno of Citium, into a more systematic framework.
Moreover, Chrysippus expanded Aristotle's logical syllogisms to include conjunctions and probability, making them more sophisticated and capable of tackling more nuanced aspects of life than Aristotle's simple "if/then" propositions.
Alexander of Aphrodisias (Aristotelian commentary)
Alexander of Aphrodisias was an important part of a tradition that saw Aristotle's works regain prominence in philosophical discussions that started about 200 years BCE. Aristotle's work had largely fallen out of public attention two generations after his death, but Alexander had a significant role in bringing this renewed interest to the Common Era.
According to the Stanford Encyclopedia of Philosophy, Alexander was such an astute critical commentator of Aristotle's writings that he developed a reputation as the pre-eminent commentator of the famed philosopher.
Galen (Medical theory)
Like his hero Hippocrates, Galen is largely known as a medical author and as one of the greatest doctors in the ancient world. Unlike Hippocrates, however, Galen was also active in his era's philosophical debates and blended the ideas of his other hero, Plato, into his own theories of the body.
Although it's hardly useful for modern doctors, Galen also developed a system of bodily elements that was heavily based on Empedocles's conception of the four elements and sought to find the physiological causes for ailments of the body and mind.
Philolaus (Pythagorean metaphysics)
Philolaus is often considered Pythagoras's most gifted disciple, and according to the Routledge Encyclopedia of Philosophy, his writings are the world's first record of Pythagoras's philosophies.
Like his main inspiration, Philolaus presented numbers as an all-powerful concept to explain the universe. But he was particularly invested in the idea of "unlimited things" and "limiting things" and saw both principles as foundational for the universe's existence and everything in it.
Gorgias (Logic)
In a 1994 article in the journal, Philosophy & Rhetoric, Frank D. Walters explained that sophists like Gorgias were often criticized as intellectual lightweights and moral relativists.
However, Walters outlined that contrary to that perception, Gorgias had a key role in developing the logical frameworks that Aristotle would perfect in his own writings. Gorgias and his fellow sophists pioneered the kind of abstract thinking that would see Greek culture shift away from reliance on mythology and towards a suitable hotbed for philosophy.
Antisthenes (Cynicism)
It's often debated whether Antisthenes was a founder of cynicism or a figure who would eventually inspire that philosophical school of thought.
Although the Routledge Encyclopedia of Philosophy presents his influence on cynicism as exaggerated, Antisthenes' statements about overcoming poverty and unpopularity by seeing its virtuous benefits show a spiritual influence on how the cynics lived. And his views also shed light on the degree that the life of Socrates inspired the cynics.
Crates of Thebes (Cynical lifestyle)
While the cynical philosophers of ancient Greece prized simple lifestyles similar to vows of poverty in later centuries, the University of Chicago-affiliated website LacusCurtius outlined that Crates of Thebes was most famous for how he committed to this lifestyle.
Although he was born into a wealthy family, he was known to spread his worldly possessions among his community and eventually rejected his land titles and riches entirely on Diogenes' advice. Poets and other philosophers of the time wrote of him dressing only as needed to survive and walking into people's houses to lecture them on their values.
Posidonius (Atlantic tides)
According to the Routledge Encyclopedia of Philosophy, Posidonius was a Stoic philosopher who blended those teachings with his own, detailed, empirical research into the natural world. As such, he developed a reputation for being the most scientific of the Stoics.
This research focus extended to astronomy and meteorology and his most famous contribution in this respect was to explain the connection between the motions of the moon and the Atlantic Ocean's tide patterns.
