Famous Ancient Philosophers

Born 624 BC Thales of Miletus
Founder of the Milesian school of philosophy, Thales was adjudged by Aristotle to be the first real scientist since he sought for the ultimate physical substance. He took this to be water and believed that the Earth floated on water like a raft. He referred to water as the arche-, the principle underlying all of reality or Being. This idea was to become very important for the Pre-Socratic philosophers who devoted much of their energies to disputes about the arche-

Although our knowledge of most of his philosophical doctrines is sketchy, based on hearsay, his 'first scientist' accolade seems justified. In 585 BC he correctly predicted a solar eclipse and he is reputed to have been responsible for the introduction of geometry to the Greek world. More generally, though, he was the first 'natural philosopher', the first (Western) thinker to clearly break with supernatural and mythopoeic explanations of the world in an effort to explain natural phenomena in natural terms. This did not mean that he rejected the notion of divine beings. To the contrary, he held that magnets possessed a soul and that, indeed, all things were similarly full of gods a version of a theological view known as panpsychism.

c 610 BC c. 546 BC Anaximander of Miletus
A student of Thales, much more is known about his philosophical and scientific achievements than of those of his teacher's. Demurring from his teacher about the arche-, Anaximander held this to be what he called the apeiron : that which is limitless, boundless and eternal. It is very difficult to know precisely what he intended by this term whether he simply meant some substance that had no determinate features or something that was either spatially or temporally unbounded.

The apeiron was to subsequently play a crucial role in virtually all Greek theories of the origin of the Universe (cosmologies), especially in Plato's cosmology as formulated by him in The Timaeus.

Anaximander was a meticulous astronomer, producing maps of the heavens (as well as of earth). Around 520 BC he proposed that Earth was a cylinder, a disk which had separated from the apeiron to be surrounded by rings of fire enclosed in air. The Sun, stars and Moon were then explained as jets of fire in the "holes" of the surrounding air. He even postulated an evolutionary process to account for the variety of animal life.

c. 580 BC c. 495 BC Pythagoras
Born in Samos, Pythagoras emigrated to Croton in Southern Italy, around 530 BC where he founded an ascetic religious sect, the Brotherhood, dedicated to the pursuit of scientific knowledge, particularly mathematics.

Their most important religious doctrine was that the soul was immortal and condemned to a cycle of birth and rebirth because of a fall from grace.

Their exclusiveness and detachment from ordinary society led to their distrust amongst the populace there and to their meeting houses being burnt down. Pythagoras was forced into exile and died at Metapontum.

It is not known how many of the Pythagoreans' discoveries can be attributed to Pythagoras himself. Even the famous theorem which bears his name was most probably discovered by his followers. One of the Pythagoreans' most profound discoveries was that musical harmony was determined by simple arithmetical ratios underlying the musical scale. This encouraged them to hope that all phenomena could be explained in terms of harmonia, number. This is part of the meaning of the gnomic claim attributed to Pythagoras "All is number".

The Pythagoreans' love of mathematics led them to venerate certain numbers and geometric forms. The Earth was deemed to be a sphere and the planets were held to move in circles on the grounds that circles and spheres were perfect geometric forms.

born c. 515 BC Parmenides
Parmenides was perhaps the most influential of all the Pre-Socratic philosophers. What we know of his views stems largely from a poem he wrote called On Nature in which a goddess reveals to him that what exists must of necessity exist. This led him to deny the reality of all change. The real world, then, is impassable, imperishable and indivisible. Parmenides called this The One. This thesis is known as Monism.

How to explain the fact that the world appears to change though? Parmenides argued that the illusion of change was generated by two equally illusory forms Light and Dark. The world accessible to the senses the world of Appearance was an illusion; the Real world was accessible only to the intellect. This striking rejection of the world manifest to our senses in favour of what pure Reason revealed to us about it was to dog philosophy evermore. It is the infamous Appearance/Reality distinction. Accompanying it was a story about how we could know Reality through the contemplative Intellect that came to be known as Rationalism. Parmenides was the single most powerful influence on Plato.

flourished c. 500 BC Heraclitus
Heraclitus stands at the opposite end of the spectrum to Parmenides on the issue of change. Where Parmenides held that nothing changes, Heraclitus believed that everything did. Little is known of his views outside of what later commentators have attributed to him the one book he produced is now lost.

Influenced by the Milesian school of Thales and Anaximander, Heraclitus posited a series of cyclical transformations of the four basic elements Earth, Air, Water and Fire. The arche-, he thought, was Fire.

His most famous doctrine was that natural changes were produced by the war or strife between opposites contraries such as heat and coldness, life and death. Indeed, he went further and claimed that each contrary required the existence of the other and that without such contraries, the cosmos would not exist.

A strong mystical element pervades his thought. He criticized his predecessors for not listening to the Logos, the ordering principle underlying the cosmos the Logos taught us that all things are one, even opposites are in some deeper sense one. It is difficult to know what this latter idea amounts to but there is no denying its influence in Eastern and other mystical thought.

c. 500 BC 428 BC Anaxagoras
Anaxagoras was the first Pre-Socratic philosopher to teach in Athens. Heavily influenced by Parmenides, he held that nothing really comes into being or passes away every object that we experience has a certain portion of each of the elements, of which there are indefinitely many. Anaxagoras took not only the most abundant physical substances such as earth, water, air etc. to be elements but also flesh, blood, bone along with the properties ordinary material objects have such as heat, texture, colour etc. The appearances of material objects are determined by whatever elements are most predominant in the mixture of elements that compose them. Nothing emerges in the world that was not already in the cosmos somewhere in some proportion with other elements.

Conjecturing that the Sun was a large hot body many times larger than the Peloponnese which shed its light on both the Earth and Moon, Anaxagoras was the first ancient astronomer to give the correct explanation for solar and lunar eclipses.

c. 493 BC c. 433 BC Empedocles
Most famous for his theory that there were but four genuine elements out of which everything else was compounded earth, water, air and fire. These he called rizomata (roots). Empedocles' account of the elements was taken to be definitive by Plato and Aristotle and through them persisted as such right through the Middle Ages up until the birth of modern science.

Like Parmenides, Empedocles rejected the reality of change. The appearance of change, phenomenal change, was explained by his rizomata. When these mix together in set proportions, compounds such as blood or milk or bone are created. The elements themselves are caused to mix or separate by two opposing forces Love and Strife. Love joins them together, Strife drives them apart.

As with many of the Pre-Socratics, he proposed an elaborate account of the origin of the cosmos, a cosmogony. His was a cyclical cosmogony in which the four elements combine to form a Sphere which is thoroughly permeated by Love. Strife then proceeds to shatter the homogeneity of the Sphere into a cosmos with all the elements earth, air, water and fire separated into distinct cosmic masses. At a certain stage in the cycle, living things are formed from heterogenous mixtures of these elements.

Empedocles was a highly astute scientist. His most important scientific discovery was that Air was a separate substance. He demonstrated this by putting a bucket upside down in water and showing that the water did not rush into the bucket as it ought to if there were literally nothing, a vacuum, in it.

He was aware of the existence of centrifugal forces, demonstrating their action by whirling around a cup of water on a string. He also knew from his observations that there was sex in plants and even proposed a rather fantastic evolutionary theory, complete with a story about survival of the fittest!

He knew that the moon shone by reflected light even though he mistakenly believed that the Sun also did. He knew that solar eclipses are a result of the interposition of the Moon between Sun and Earth. He claimed that light takes time to travel but moves so quickly that we cannot observe it. He founded the Italian school of medicine which had a great influence on both Plato and Aristotle.

Born c. 490 BC ? Zeno of Elea
Zeno of Elea was a pupil of Parmenides who produced some ingenious arguments to show that it was an illusion to think that Reality was divisible into parts or subject to change. These arguments came to be known as Zeno's Paradoxes. Here is one:

Achilles, the fastest athlete of his time is pitted against Zeno's pet tortoise Tedios to test Zeno's boast that Achilles can never catch Tedios if he gives him even the smallest of starts. Achilles can run ten times faster than Tedios. So it is agreed that they will race over 100 metres and that Tedios will be given 10 metres start. The race begins and Achilles covers the 10 metres separating him from the tortoise in a blinding second. Tedios meanwhile has barely managed to plod one metre. Still he is ahead if only by one metre and if not for long. Achilles makes up the metre separating him from the tortoise in 0.1 second. In that time, Tedios has travelled just 0.1metres. Fractionally behind the tortoise, it takes Achilles only 0.01seconds to span the gap separating him from Tedios. Yet in that time Tedios has plodded forward 0.01metres, still ahead if too close to call! in this manner, Achilles will never succeed in overtaking the tortoise! Yet our senses attest that he will do so with ease. Clearly, then, our senses deceive us and motion is an illusion!

A paradox related to this is the Racetrack Paradox which essays to show that a runner can never reach the end of a race since to do so she would have to traverse the point halfway between the start and the finish, but to traverse that point, she'd have to traverse the point midway between the start and the halfway point and so on.

The Arrow Paradox also attempts to persuade us that motion is impossible. An arrow in flight occupies a portion of space equal to itself at any one moment or instant of time.

But since motion takes an interval of time, the arrow cannot be moving at an instant. Thus for every instant the arrow is not moving, which means that the arrow does not move at all. So motion is impossible.

Zeno also propounded other arguments showing that objects are both limited and unlimited in number, are both like and unlike each other, are both one and many, large and small. The aim seems to have been to show that all attempts to divide Reality into any sort of plurality fail.

c. 470 BC 399 BC Socrates
Unlike the Pre-Socratics, Socrates' central concern was how to live virtuously rather than the nature of the Universe. This is reflected in his famous claim "The unexamined life is not worth living."

Socrates engaged in public debate people who professed opinions about the nature of courage or of right conduct. Often these debates took place in the market-place.

Socrates' foes were the Sophists who apparently earned their living by teaching people how to argue. The Sophists epitomized everything Socrates opposed they charged substantial fees for their services, where Socrates would accept no payment. They claimed to possess knowledge and to be able to communicate it to others, where Socrates only claimed to seek knowledge and, ironically, to possess no knowledge. Their express aim was to win arguments, not discover the truth and they often did so, according to Plato, by intellectual trickery. In short, they were the lawyers of their day.

A highly influential figure here was Gorgias who apparently held that language was incapable of getting at the truth but could certainly be used by the skilful orator to persuade or to deceive his hearers.

Another very influential Sophist, Protagoras, was famous for his claim that "Man is the measure of all things, of those that are, that they are, and of those that are not, that they are not."

What then did Socrates offer as an alternative to the Sophists' rhetoric? His method is often referred to as the method of Elenchus, which is the Greek word for refutation. The Elenchus proceeds thus:

The upshot of the elenchic method is not purely negative, according to Socrates. Something has been achieved even if in the process a state of perplexity or aporia has been induced in the unfortunate interlocutor the pretence of knowledge has been replaced by an awareness of ignorance. But this, Socrates thought, was necessary for genuine knowledge of virtue.

Eventually brought to trial for introducing strange gods and corrupting the youth of Athens, Socrates famously refused to flee from Athens and thus break the law, as he could have done, choosing instead to take his own life by drinking hemlock, thereby fulfilling the sentence of execution passed on him. Plato's dialogues Crito and Phaedo recount the circumstances of Socrates death and the latter's bravery in facing it.

c. 429 B.C. 347 B.C. Plato
Plato, together with his equally illustrious pupil Aristotle, is the most famous and influential of all Ancient philosophers. Unlike most of the other Ancients, his writings are extensive and have survived to the present. They consist of a series of Dialogues which are conventionally divided into three broad groups: the Early, Middle and Late. The Early Dialogues present Socrates pursuing his questions about virtue.

Socrates typically wishes to know "What is V?" where V stands for some virtue such as courage or love or justice. Socrates is not interested in producing mere examples of courage or justice, he wishes to know what all such examples have in common what makes certain actions courageous, other actions just? The common property that all instances of some virtue such as courage or justice or virtue share is called the Form of that virtue.

The Middle Dialogues proceed to develop the theory of Forms but do so without the Socratic method of elenchus. In fact, these 'dialogues' are not dialogues at all. It is in the Theory of Forms that Plato's deep debts to Parmenides, Heraclitus and Pythagoras are most clearly evident. His theory is to a large extent a synthesis of their ideas.

Yet whilst Heraclitus maintained that everything changes, Parmenides held that nothing did! So how could any synthesis of their views possibly be coherent?

Plato avoids conflict between these two contradictory views by applying them to different domains. Heraclitus's theory is true of the world of Appearances, the physical world revealed through our senses there everything is in a state of flux.

Parmenides view, on the other hand, describes a world behind the world that is presented to our senses a world of numbers, shapes and geometric figures which form the invisible patterns on which the objects we see are designed. In this invisible world there are designs and blueprints not just for physical objects but quite literally for anything one can think of! There is a Form of Beauty, a blueprint by which every beautiful thing in the world is made beautiful; there is a Form of Justice by means of which every just act is made just; there is a Form of Man and a Form of Woman, Forms of animals, plants, inanimate objects, even artefacts like beds and jugs have their own distinctive Forms in Plato's abstract heaven. The highest Form of all is the Form of the Good.

It is this world which for Plato is the real world. It is a world that is not revealed to the senses and it is only of this world that one can have genuine knowledge. This knowledge is to be acquired through the intellect, by means of philosophy.

Plato and Aristotle

384 B.C. 322 B.C. Aristotle
Where Plato emphasized the unities underlying things, Aristotle stressed their diversity. Aristotle was the champion of the particular and the individual where Plato advocated the universal and the general. He disputed Plato's theory of Forms and proposed an alternative in which forms inhere within those objects they serve to structure rather than within a transcendental realm quite removed from the real world. To explain why individual things were as they were Aristotle posited individual essences that made them that way. Objects consisted of matter imbued with form.

Aristotle's explanations for why events occurred in the way that they did were teleological or purposive: things happened in the way they did because it was best for them to do so. So the iron filing moves toward the magnet because it has a 'sympathy' for the magnet, it is best for the iron to be in that state. The natural state for terrestrial objects was rest, Aristotle held. In contrast, the natural state for celestial objects was circular motion. Thus he held, following Pythagoras, that the planets moved in circular orbits around Earth. The Sun also circled Earth he thought.

Scientific explanation dealt with the ultimate causes of things, Aristotle believed. To that end, he discerned four different sorts of first principles or ultimate causes:

Modern science only needs to recognize the third sort of cause, efficient causes.

Before any scientific explanation can proceed, though, things must be sorted into their appropriate Categories, Aristotle believed.

As to any individual thing we can ask to its:

Take Socrates as an example. The primary substance of the famous philosopher is just Socrates, the individual person. Of this primary substance, Socrates, secondary substances in the form of the species and the genus to which Socrates belongs, can be predicated. Thus Socrates belongs to the Human Species and the Genus of Animal. So both 'human' and 'animal' can be predicated of the primary substance Socrates.

Aristotle is also famous for his logical theory, being the first thinker to try to systematize human reasoning in the form of what he dubbed Syllogisms. His theory turned on the recognition of four main forms of categorical statements "Every thing which is F is G", "No thing which is F is G", "Some thing which is F is G", "Not every F is G". He gave names to some of the correct or valid Syllogisms involving these categorical statements. Thus one particularly important valid Syllogism was called Barbara and in Aristotle's view represented the common form for scientific explanations:

As well as his interest in science, Aristotle is noted for his profound writings on moral theory and human psychology. The Greeks thought of the soul as the source of life. In Aristotle's terminology the soul (psyche) was the form of a body with the potentiality for life. Aristotle regarded it as a complex of cognitive faculties which he sketched in his treatise On the Soul.

In moral theory Aristotle rejects Plato's idea of a transcendent Form of the Good as something which is completely irrelevant to human affairs. Human choice and action are aimed at the good, to be sure. But there is no presumption that there is any absolute good. Rather the good that is aimed at is simply that which is good for human beings, that which promotes human flourishing. So the end or telos of human action is happiness (eudaimonia). It is that which is the final good for humans. Virtues, however laudable in their own right, are sought also for the sake of eudaimonia. One acquires moral virtue (ethike arete), he thought, by acquiring a stable disposition (hexis). The person of practical wisdom (phronesis) is one who reliably chooses actions that lie between extremes. Such actions will lie in a mean relative to the abilities and the projects of the agent. This is the origin of the popular notion of the "golden mean".