Plato’s Philosophy: 10 Breakthroughs That Contributed to Society

Plato’s philosophy was informed by Socrates and addresses a range of topics from the metaphysical to the everyday practical. Here are ten of his best breakthroughs in ancient Greek philosophy.

Nov 15, 2020By Michael Arnold, BA Art History, MA Ancient Mediterranean Archaeology
death of socrates plato
The Death of Socrates by Jacques Louis David, 1787, via The Metropolitan Museum of Art, New York


If the concerns of Classical Greek Philosophy were reduced to three words, they’d be truth, beauty, and goodness.


Thoughtful observation of the concepts behind these words brings one closer to the beneficent intelligence of the universe that Plato’s philosophy so often references.


A disciple of Socrates, his works gave birth to the school of Platonism and then its offshoot, Neoplatonism. The Neoplatonists inspired St. Augustine, whose writings and ministry heavily influenced Christian doctrine taking form around the turn of the 4th century AD.


Plato and Socrates were concerned with “The Good,” “The Beautiful,” truth, justice, the higher self, and the nature of the human soul. We see these topics, among others, as the predominant objects of discourse in Plato’s writings on Socratic dialogues.


The School of Athens by Raphael, 1509-11, in The Apostolic Palace, Vatican City, via Visit Vatican


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In his seminal work, The Republic, Plato discusses the organization of various types of states. But he begins by exploring the internal organization of the human soul, forging a clear link between the health of the individual and that of the greater society. Above all, he emphasizes the importance of going deeper within oneself in search of eternal truth. 


Plato’s Philosophy: Here Are 10 Fascinating Breakthroughs From The Encyclopedia Of Philosophy


1. Justice Is The Sum Of All Virtue; Virtue Is Happiness


“We are looking for justice, a thing much more precious than gold.” – Socrates, The Republic of Plato


Head of Plato, mid-3rd century AD, Roman Empire, via The J. Paul Getty Museum, Los Angeles


Plato asserted that a just person enjoys “internal order,” while the unjust is at odds with himself. It might seem natural for a philosopher to value exploration of the “inward self.” But Plato seems to suggest that this is, in fact, integral to the pursuit of justice.


To live a just life, one must aim to be virtuous because virtue is a prerequisite for knowledge. And true knowledge, as opposed to mere belief, is man’s closest link to the divine.


A skeptic of democracy, Plato proposed that nations should be ruled by “philosopher kings,” or high-minded individuals dedicated to the pursuit of justice and learning. The philosopher king, after having attained a certain degree of wisdom from study and reflection, would seek to inspire the governed to equally pursue virtue.


For the philosopher king makes no use of public opinion, or, in Plato’s words, the “Great Beast.” Rather, his mind is fixed only on truth for truth’s sake.


Unlike most men, the philosopher king knows what life is worth living for because he has knowledge of “The Good” a concept that’s expounded in a later breakthrough. Happiness is the product of this knowledge, and in order for one to attain happiness, he must first pursue virtue in all things.


A key insight of Plato’s philosophy is that the pursuit of justice is more profitable in this life than injustice. Those who are truly just know pleasure, while the unjust mistake pleasure for the absence of pain.


2. On The Nature Of The Divine


Statuette of Aphrodite, 2nd century BC, Eastern Mediterranean, via The J. Paul Getty Museum, Los Angeles


During Plato’s lifetime, educated Greeks no longer believed in the actual existence of gods called Apollo, Zeus, and Aphrodite. As Greek religion didn’t require faith, it’s inferred that he also fell into this category.


In his dialogues, he uses the names of various gods, as well as the singular “God,” and “universe” interchangeably.


He had many breakthroughs on the divine, and it’s no surprise being that much of Plato’s philosophy is metaphysical in nature. But high amongst the most interesting is his professed belief in reincarnation. Plato refers to a “wheel of birth” that the “purified soul” can escape from to “dwell with the gods forever.”


He claimed that these gods, or God, have no responsibility for evil in this world, an idea that is alive in Christianity through the concept of original sin: God is the benevolent creator of all things and man’s evil is a product of his misdirected will or illusion.


God has “immunity to change from the outside” because He is already in the highest state of perfection. At the time of writing, this would have been understood as a rebuke of the Greek gods and their meddling on Earth, often disguised in human or animal form.


3. On The Equality Of Women

Painted pottery depicting Greek woman, 450 – 40 BC, Attica, via the British Museum, London


Plato acknowledged the physical strength disparity between the male and female sexes. But in all other regards, he believed woman to be man’s equal, and that no opportunity should be denied to her on the basis of sex.


In his description of the ideal state, Plato elaborates on this point in the person of Socrates. “The same natures,” he announces at the end of a dialogue on the equality of women, “must be allowed the same pursuits.”


It’s obvious to contemporary readers. But this viewpoint was controversial in the Ancient Mediterranean World, where egalitarian societies were almost non-existent, and even within the greater spectrum of Greek philosophy of the time.


Greco-Roman women, in particular, had no voice or representation. So to make such a sweeping declaration about the equality of the sexes was a major breakthrough. And one wonders if it set the philosophical groundwork for the broad acceptance of this idea much later in Western history.


4. Three Parts Of The Soul

Orphic Mosaic, 4th century AD, Isle of Wight, via Brading Roman Villa

Plato subscribed lightly to Orphism, an ancient religious cult of the god Orpheus that promoted worldly asceticism and eternal life of the soul.


So, perhaps influenced by this, every human person has a soul in Plato’s philosophy. And each soul has three parts: the rational, the irrational, and the spirited.


The rational is “reflective,” meaning it seeks knowledge, order, and discipline through internal reflection. The irrational satisfies appetite and can be summated as any impulse that distracts the rational, e.g., sex drive, hunger, and passion. The third part, the spirited element, animates either of the first two. Ideally, it should be what Plato calls the “auxiliary of the rational,” animating the soul toward reason and discipline.


5. Essential Forms Of Greek Philosophy

Sketch of Plato’s Symposium by Pietro Testa, 1648, via The Metropolitan Museum of Art, New York


“Doxa” is the ancient Greek word for anything that appears or seems to be; in other words, the world that can be perceived with the five senses. In Plato’s philosophy, this doxa world is less real than that of the essential forms. Unchanging and eternal, essential forms are the only true objects of knowledge.


An essential form is an invisible, intelligible principle that is unified and unalterable. This is quite abstract for philosophy newbies. And a good analogy to use for illustration is a scientific law of nature or a mathematical rule: it’s indisputably real, but you can’t see it. In fact, it’s even “more real” than anything you can perceive at this moment, because it will still exist in its perfectly unchanged form long after everything you’re perceiving now is gone.


In The Republic, Plato explores in detail the nature of the essential form of beauty, a fascination of Greek philosophy. At its essence, beauty is unified, unchanging, and eternal. Recognizing a manifestation of beauty in a person or thing is not knowledge of its essence. It is only belief in an isolated manifestation. 


The Vetruvian Man by Leonardo da Vinci, drawn to explore the ‘golden ratio,’ 1490, via Gallerie dell’Accademia, Venice


True knowledge of the essential form of beauty comes with the understanding that it is greater than any given instance of its manifestation in any multitude of forms.


“Now if a man believes in the existence of beautiful things, but not of Beauty itself,” Socrates says, “and cannot follow a guide who would lead him to a knowledge of it, is he not living in a dream?”


In this quote, Plato, in the person of Socrates, is saying that any manifestation of beauty in the World of Appearances is merely a semblance of its essential form. And that conflating the semblance and the real thing requires one to participate in an illusion.


The essential form versus doxa relationship is analogous to something’s fundamental essence versus the things that partake of its character. So while many have “belief” of beauty from what they can perceive, few have knowledge of its true and eternal form.


6. “The Good” As The Highest Object Of Knowledge


“Let me remind you of the distinction we drew earlier between the multiplicity of things that we call good or beautiful or whatever it may be and, on the other hand, Goodness itself or Beauty itself and so on. Corresponding to each of these sets of many things, we postulate a single Form or real essence.” – Socrates speaking to Glaucon, The Republic of Plato


Mosaic of the Academy of Plato/Seven Philosophers, 1st century BC, via Roman National Archaeological Museum, Naples 


Without knowledge of The Good one misses the value in all other things. Because, according to Plato’s philosophy, The Good makes the world intelligible. And the apprehension of it is a revelation which can only follow a long intellectual training, like that of the philosopher king.


In The Republic, Socrates cannot describe The Good in certain terms. But he uses an analogy to emphasize its importance.


He says that the objects of knowledge are made visible and nourished by “Goodness” in the same way light from the sun enables sight and knowledge of objects on the Earth. In this way, the objects of knowledge derive their very being from The Good. Therefore, Goodness isn’t the same as being, but surpassed it.

Its essential form is greatest because it gives life to all the others and is the last to be perceived, and only with extreme difficulty.


Plato proclaimed The Good to be the highest object of the “Intelligible World,” which is composed of essential forms and mathematics. This Intelligible World corresponds to the states of knowledge (episteme) and thinking (dianoia) in man.


The “World of Appearances,” that of visible things and images, corresponds to the lesser states of belief (pistis) and imagining (eikasia) in man. Pistis is a lower form of cognition because it’s detached from all knowledge of The Good and the essential world to which it gives life. It’s completely attached to that which is visible, and, therefore, merely a fleeting semblance of the real thing.


7. The Allegory Of The Cave

The Allegory of the Cave by Anton Dymtchenko, 2016, via Anton Dymtchenko Art


Perhaps the most well-known topic in the Encyclopedia of Philosophy, the allegory of the cave is a commentary on the condition of man in relation to truth and illusion.


Plato puts forth a scenario in which a group of humans are born into a chamber within a cave. They spend their lives in this place, knowing nothing of the outside world. At some point beyond their immediate surroundings, light from the cave’s entrance floods in from the outside. But, of course, they have no awareness of this.


The cave dwellers are chained in a position such that they only see what is directly before them. And what’s before them are silhouettes on a wall made by shadows cast from puppet masters in front of a fire to their rear.


The whole reality of these imprisoned cave dwellers, therefore, is the movements of the shadows on the wall before them.


This parable illustrates Plato’s teachings on the World of Appearances versus the Intelligible World. He’s making the case that, by and large, the state of humanity is akin to the cave dwellers. What we think of as real, or doxa, is actually an illusion or a mere shadow of reality. 


Illustration of Plato’s Allegory of the Cave, via Medium


And the real world, that most don’t even have the faintest inkling of, is taking place outside of the cave.


Now suppose one of the cave dwellers were released from his chains and managed to leave the cave. “When he had come out into the light,” Socrates says, “[would he not] find his eyes so full of its radiance that he could not see a single one of the things that he was now told are real?”


He would need to “grow accustomed” before seeing the “things of the upper world,” in the same way humans must put in time for study and reflection to have knowledge of the forms of the Intelligible World.


8. On The Ideal State

The Parthenon by Edwin Church, 1871, via The Metropolitan Museum of Art, New York 


Plato dedicates several chapters of The Republic to a characterization of the ideal state.


As noted earlier, this state would be ruled by a philosopher king. And the governing class would not be hereditary because, above all things, the ideal state values promotion by merit.


It should also be wary of “great wealth,” as it tends to weaken the state by setting up internal class war. Both “luxury and idleness” as well as poverty have a “subversive tendency,” according to Plato. Aggression is a product of the unchecked growth of luxury.


Unity, another theme pervasive throughout Plato’s philosophy, is essential to the health of the state. Citizens should be so closely bound by institutions that they all want the same things.


“When one of us hurts his finger, the whole extent of those bodily connections which are gathered up in the soul and unified by its ruling element is made aware and it all shares as a whole in the pain of the suffering part,” Socrates says.


This analogy of the unified experience of the human body speaks to Plato’s urging that when one part of society hurts, the whole of society should feel it. Acting as one body makes for a strong and healthy state.


9. On The Importance Of Studying Mathematics

Platonic Solids Augmented Reality Art Exhibition by Lalie S. Pascual, 2014, Grand Central Station, New York, via Lalie S. Pascual’s Website


The objects of pure thought are numbers and forms. And, therefore, mathematics earns its place in the higher, intelligible world.


This conviction is rooted in the assertion that there is no truth to be found in changing things. Geometry, for example, is “knowledge of the externally existent.” Alternatively, other subject matters, such as the natural sciences, study things that “come to be this or that at some time and then cease to be.”


For this reason, the study of mathematics during a person’s formative years is extremely important in Plato’s philosophy on the ideal state. A familiarity with abstract mathematical concepts would engender in students the aptitude for attaining knowledge of the essential forms.



Sketch of the Plato’s Geometric “Platonic Solids” by Augustin Hirschvogel, 1543, via The Metropolitan Museum of Art, New York


In fact, Plato went as far as to say that there really is no learning. And that learning is actually a recognition of prior knowledge, or “a priori,” from former lives of the soul. This knowledge of existing and immutable truths becomes particularly evident when studying mathematics, which “awakens the power of thought” and “draws us towards reality.”


10. Proof Of The Immortality And Indestructibility Of The Soul 

Flower of Life/Plato’s Sacred Geometry of the Eternal Soul, via The Soul Matrix


In the Phaedo, Plato’s dialogue on the soul, death is described as the soul separating from the human form. And in The Republic, a justification for its immortality appears.


His logic is as follows: everything has a “peculiar evil” which corrupts and ultimately destroys it. The human body, for example, becomes corrupted by external forces such as bad food or poor lifestyle. It will eventually succumb to these forces, but cannot be solely destroyed by anything foreign. Its own diseased state, acting with the bad food, will lead to its death.


Therefore, the body is destructible, and the destruction occurs when a foreign evil acts upon an already diseased internal state.


The soul, however, does not dissolve when it’s corrupted by wickedness and depravity. It can go on in that condition, which is antagonistic to its essence until the body dies and the soul is released.


It is therefore established, according to Plato’s philosophy, that “the soul is not destroyed by any evil, either of its own or another’s,” and that “clearly it is a thing that exists forever, and is consequently immortal.”


Plato’s Philosophy On The Condition Of The Soul

Mosaic of Memento Mori, an ancient symbol representing the transience of life (skull) beneath a butterfly (soul) balancing on the wheel of fortune, 1st century BC, via Roman National Archaeological Museum, Naples


There is ample material on the condition of the soul in the Encyclopedia of Philosophy, but Plato’s summation is perhaps among the most beautiful:


“Our description of the soul is true of her present appearance; but we have seen her afflicted by countless evils like the sea-god Glaucus, whose original form can hardly be discerned, because parts of his body have been broken off or crushed and altogether marred by the waves, and the clinging overgrowth of weed and rock and shell has made him more like some monster than his natural self. But we must rather fix our eyes on her love of wisdom and note how she seeks to apprehend and hold converse with the divine, immortal, and everlasting world to which she is akin, and what she would become if her affections were entirely set on following the impulse that would lift her out of the sea in which she is now sunken, and disencumber her of all that wild profusion of rock and shell, whose earthy substance has encrusted her, because she seeks what men call happiness by making earth her food. Then one might see her true nature, whatever it may be, whether manifold or simple.” – Socrates speaking on the condition of the soul, The Republic of Plato


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By Michael ArnoldBA Art History, MA Ancient Mediterranean ArchaeologyMichael is a contributing writer and former world traveler whose hometown is New York City. He spent the majority of 2019 exploring Europe, the Middle East, and North Africa. And currently, he’s studying for a masters degree in Ancient Mediterranean Archaeology at the University of Pavia in Italy. In his spare time, Michael enjoys researching and writing about art, history, and archaeology with a focus on the ancient world.