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Oversimplified ideas of the great philosophers of all times

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    Aryan Ebrahimpour
  •   25 min read


One of my favorite topics, besides computer science and STEM, is philosophy. I've been reading various books on philosophy lately. Here's a list of the books I have already read or plan to read in the near future:

  • Gaarder, Jostein. "Sophie’s World."
  • Wilkinson, Hugo, and Chauney Dunford. "Philosophers: Their Lives and Works." (2019).
  • Durant, Will. "The Pleasures of Philosophy a Survey of Human Life and Destiny." (1953).
  • Handley, Rachel. "Philosophy Through Science Fiction Stories: Exploring the Boundaries of the Possible." The Philosophers' Magazine 95 (2021)
  • Arp, R., & Cohen, M. (2018). Philosophy Hacks: Shortcuts to 100 ideas. Cassell.
  • Blackburn, S. (2016). What Do We Really Know?: The Big Questions in Philosophy. Quercus Publishing.

In this blog post, my intention is to create a condensed summary of the ideas from the greatest philosophers throughout history. This summary will serve as a personal reference for me to revisit and reinforce my understanding of their concepts. Additionally, I aim to share this summary online so that others can know what I have grasped from their ideas.

Philosophers from Ancient history

Laozi, 571 BC

Known as the author1 of Daodejing (also known as "The Classic of the Way and of Virtue"). His idea in Chinese is called Wu Wei (means "inaction"). By "inaction" however it doesn't necesserily mean not doing any actions, but to do in bare minimum needed until the rest is done spontaneously.

Confucius, 551 BC

Known as the most impactful teacher in the whole history of China. He is the author of Analects2, which not only includes his teachings, but also how to teach. Ren and Zhi are two fundamental virtues of Confucianism. Ren means "humanity" and "goodness" to help eachother, and Zhi means "Wisdom" (the ability to distinguish between right and wrong). Ren is stable and still like a mountain, but Zhi is flexible and fluent, like a river.

Siddhartha Gautama (Buddha), 480 BC

Buddha means "Awakened One", or "Enlightened One". His teaching was to overcome Dukkha ("pain" or "dissatisfaction") with everyday life.

As an example, imagine someone who've been shot at by an arrow. Buddha explains that immediately after the first arrow, the person gets shot by a second arrow. The first arrow is the physical pain and inevitable. The second arrow, however, is the mental distress in response to the physical pain. This kind of pain can be reduced or completely ignored. Buddha not only introduced such intellectual system, but also practical practices which are called Sila and Samadhi.

Diotima of Mantinea

She was inspiring to Socrates, and gave the basics of the "Platonic love" concept (love without sexual desires) to Plato. Based on Diotima's Ladder of Love, there are six types of love, and each kind is put on a rung of a ladder. Love for a particular body, Love for all bodies, Love for souls, Love for laws and institutions, Love for knowledge, and in the final rung, Love for Beauty itself.

Socrates, 469 BC

Socrates is described as "The Gadfly of Athens" by Plato. Unlike pre-Socratics philosophers who tried to understand the metaphysics of the universe, Socrates tried to understand the basic human concerns like ethics, justice, and virtue. He has many notable ideas like "I know that I know nothing" known as the Socratic paradox. And "The dissimulation of ignorance practised as a means of confuting an adversary" known as the Socratic irony.

Diogenes of Sinope, 412 BC

Diogenes is famous for two things: challenging traditions in a violent and insulting way, and the austeriry and simplicity of his life based on his Cynic philosophy. Diogenes maintained that all the artificial growths of society were incompatible with happiness and that morality implies a return to the simplicity of nature.

Plato, 428 BC

Plato is one of the most impactful philosophers in the western philosophy. He was one of the most notable students of Socrates and documented his legal self-defence in the Apology of Socrates. He was against the Athenian democracy, a system of government where all the non-slave male citizens could attend in the assembly which governed the city-state. He believed either philosophers should be kings and rulers, or kings should have the power of philosophical thinking (which led to the creation of the concept of "Republic"). He also believed in the "Theory of Forms". In this theory, all objects and matter in the physical world are merely imitations of "Ideas" or "Forms" that are the non-physical essences of all things.

Aristotle, 384 BC

Unlike his teacher Plato, Aristotle had a natural approach in philosophy. He was interested in biology, specially studying sea creatures. In contrary to theory of forms, he believed that there is only one universe, and it's the one that we're living in. Aristotle believed that knowledge should be obtained via natural experiments, unlike his teacher Plato who believed that knowledge is intrinsic, and we can achieve it only by thinking.

Aristotle has many contributions in Theoretical philosophy (e.g. Aristotelian logic, Hylomorphism, the four causes, Unmoved mover, etc), Natural philosophy (e.g. Aristotelian biology and physics, Common sense, etc.), and Practical philosophy (e.g. Aristotelian ethics, Golden mean, Natural slavery, etc.).

Mencius, 371 BC

Mencius, also known as Mengzi, is one of the most notable Confucianist philosophers. He believed that human nature is righteous and humane. This placed him at odds with his near contemporary, Xunzi, who believed that human nature is evil by birth.

Master Zhuang, 370 BC

He had a simple life in nature far from society, which was consistent with his Taoist beliefs. "Tao" means "Way", and is generally defined as the source of everything and the ultimate principle underlying reality. He is the author of Zhuangzi, a Chinese text containing stories and anecdotes that exemplify the carefree nature of the ideal Taoist sage.

Epicurus, 341 BC

Epicurus's Liberal Materialism is oftenly misinterpreted as the symbol of extreme hedonism (a philosophy around the idea of desires to increase pleasure and to decrease pain). This interpretation is actually the opposite of the philosophy he promotes in his school, known as "The Garden".

He believed that the goal of life is to live happily and with pleasure. He however recommended moderate pleasure and peace of mind, and avoiding the fear of death, rather than physical pleasures.

Marcus Aurelius, 121 AD

He was an Stoic philosopher who became the Roman emperor at the age of 40. He was respected as the "Philosopher King", as the realization of Plato's ideal. He is the author of the "Meditations", which he described Stoic philosophy in. The Stoics are known for teaching that "virtue is the only good" for human beings, and that external things, such as health, wealth, and pleasure, are not good or bad in themselves but have value as "material for virtue to act upon".

Nagarjuna, 150 AD

He is one of the most important and impactful Buddhist philosophers. He is the founder of Madhyamaka or "The Middle Way" school. He discerns two levels of truth, (1) conventional truth, and (2) ultimate truth. "Things" do not really exist: this is the ultimate truth (also known as emptiness). But we can see some of "things" like trees and birds. So they exist in the sense that we can see them. This is the conventional truth. However, the existence of those things are dependent on other "things", like our perception and eyes.

Augustine of Hippo, 354 AD

He was a theologian and philosopher of Berber origin. He was against slavery and boldly wrote a letter urging the emperor to set up a new law against slave traders and was very much concerned about the sale of children. He saw the human being as a perfect unity of soul and body. As a bishop, he warned that one should avoid astrologers who combine science and horoscopes. According to Augustine, they were not genuine students of Hipparchus or Eratosthenes but "common swindlers".

Hypatia, 355 AD or 370 AD

She was the most famous astronomer and mathematician of her time, as well as a prominent Neoplatonic teacher and philosopher. Neoplatonism is a philosophical and religious system developed by the followers of Plotinus, which led Hypatia towards mathematics and its abstractions. She is known to have edited at least Book III of Ptolemy's Almagest, which supported the geocentric model of the universe.

More philosophers from Ancient history

If you're interested you can read about more philosophers of the ancient history:

Philosophers from Middle Ages

Boethius, 475 AD

Boethius is one of the greatest philosophers of the classical period. Due to some political conflicts, he got arrested and jailed in 522 AD. In prison he wrote his masterpiece "On the Consolation of Philosophy". Boethius writes the book as a conversation between himself and a female personification of philosophy who visits him in the prison. Philosophy consoles Boethius by discussing the transitory nature of fame and wealth ("no man can ever truly be secure until he has been forsaken by Fortune"), and the ultimate superiority of things of the mind, which she calls the "one true good". She contends that happiness comes from within, and that virtue is all that one truly has, because it is not imperiled by the vicissitudes of fortune.

Ibn Sina (Avicenna), 980 AD

Ibn Sina is the polymath author of the "The Book of Healing" and "The Canon of Medicine" encyclopedias. The Book of Healing is a scientific and philosophical encyclopedia, and The Canon of Medicine is an encyclopedia of medicine in five books. Ibn Sina's corpus includes writings on astronomy, alchemy, geography and geology, psychology, Islamic theology, logic, mathematics, physics, and works of poetry.

Floating man (also known as flying man) is one of the thought experiments by Ibn Sina to argue for the existence of the soul. The floating man argument is concerned with one who falls freely in the air. This subject knows himself, but not through any sense perception data. Floating or suspending refers to a state in which the subject thinks on the basis of his own reflection without any assistance from sense perception or any material body. This mind flutters over the abyss of eternity. Similar to the French philosopher Descartes (1596–1650) pointed out the existence of the conscious self as a turning point in epistemology, using the phrase "Cogito ergo sum," known as "I think, therefore I am" in modern english translation, Ibn Sina had referred to the existence of consciousness in the flying man argument in 11th century (nearly 600 years before Descartes).

Anselm, 1033 AD

Known as the father of the scholastic tradition, Anselm was the philosopher monk of Canterbury. He believed that faith is more valuable than logic, but he wanted to strengthen faith with logical arguments. In his two writings called Monologion (conversation with self), and Proslogion (conversation with others) he introduces two arguments to support the existence of God: (1) cosmological argument, and the highly controversial (2) ontological argument. In cosmological argument, Anselm claims that all the natural things need a greater external power to exist. In ontological argument, Anselm claims that if we accept that God is a being which none greater can be conceived, then God must exists in reality, because if the God is only in our imagination, then a greater god (the God in reality) is imaginable, and that's contradictory. Philosopher Immanuel Kant (1724 AD) gave an objection to the argument, although it would be toward ontological arguments in general, rather than at Anselm specifically.

Hildegard of Bingen, 1098 AD

Known as "The Sibyl of the Rhine", she was one of the most impactful composer, philosopher, mystic, visionary, and a medical writer of the Middle Ages. She is revered as an early example of a feminist thinker. Scivias is the name of her illustrated work describing 26 religious visions she experienced. She is one of the best-known composers of sacred monophony, as well as the most recorded in modern history. She has been considered by scholars to be the founder of scientific natural history in Germany. She did not accept the inferior status of women in her era, and rejected male authority both in the ecclesiastical matters and in the music composition.

Héloïse, 1101 AD

Writer, philosopher of love and friendship, and the French nun, Héloïse, was one of the pioneers of the feminist thought. She is famous for her love story with Peter Abelard (who became her colleague, collaborator and husband), and the exerting critical intellectual influence upon his work and posing many challenging questions to him such as those in the Problemata Heloissae. The Problemata Heloissae (Héloïse's Problems) is a letter from Héloïse to Abélard containing 42 questions about difficult passages in scripture, interspersed with Abelard's answers to the questions.

Ibn Rushd (Averroes), 1126 AD

He combined Greek and Islamic thoughts. His philosophical works include numerous commentaries on Aristotle, for which he was known in the Western world as The Commentator and Father of Rationalism. Averroes was a strong proponent of Aristotelianism; he attempted to restore what he considered the original teachings of Aristotle and opposed the Neoplatonist tendencies of earlier Muslim thinkers, such as Al-Farabi and Avicenna. He proposed the "unity of the intellect" philosophical theory which asserted that all humans share the same intellect. He believed that not only religion and philosophy are complementary to each other, but the truths of philosophy and the Holy Book should also be consistent.

Zhu Xi, 1130 AD

He created an impactful philosophical system which is known as Neo-Confucianism. Neo-Confucianism slowly stopped the influence of Buddhism (which was considered foreign in China). The core of Zhu Xi's philosophy is the relation between these two concepts: "Li" (meaning rational principle, law, or organisational rights), and "Chi" (aka Qi, meaning vital energy, material energy, or simply energy3). Li is not possible without Chi, and vice versa.

As an example, for a "human", Chi is what the human is made of and keeps them healthy, while Li is both the physical and moral principles, e.g. having two hands, having two eyes, showing wisdom, practicing rituals, etc.

Moses Maimonides, 1135 AD

Maimonides was the physician, the lawyer, and the philosopher who first adapted Aristotle's teachings to Jewish theology in his masterpiece, "The Guide For The Perplexed". He believed that God's nature will always remain unknown because it is beyond human understanding. He also believed that the meaning of the Torah (Hebrew Bible) should not be taken literally, and wherever it contradicts wisdom, we should try to interpret it (which happened to be very controversial among the Jewish scientists of the time).

Albertus Magnus, 1200 AD

Known as the "Doctor Universalis" because of the vast of his knowledge. He combined Aristotle's thoughts with Christian teachings. He wrote about different topics, most notably the systematic study of minerals. His "De Mineralibus" is a five-volume book that became a benchmark text in mining, mineralogy, chemistry, and metallurgy. He also Discovered of the element Arsenic. As the teacher of Thomas Aquinas, he had important impacts in philosophy.

Thomas Aquinas, 1225 AD

He was an Italian Dominican friar and priest, and known as the most influential thinker of the Middle Ages. He is the author of "Summa Theologica", in which he not only written a detailed description of Aristotle's thoughts, but also expanded them and adopted them to Catholic ideas (in other words, made a mixture of science and faith). He believed that mocking the judgment of reason is mocking the judgment of God, and there is no conflict between philosophy and reason with church beliefs.

William of Ockham, 1285 AD

He believed that God can not be known directly, and God will always be incomprehensible to mankind. Therefore, in contrary to Thomas Aquinas's belief, he did not accept the possibility of knowing the existence of God with mere reason, and believed that faith is necessary for this. Although he remained faithful to Catholicism, he gave way to agnosticism (the view or belief that the existence of God, of the divine or the supernatural is unknown or unknowable).

He is also known for the Ockham's razor (aka the principle of parsimony or the law of parsimony). It is generally understood in the sense that with competing theories or explanations, the simpler one, for example a model with fewer parameters, is to be preferred.

More philosophers from Middle Ages

If you're interested you can read about more philosophers of the middle ages:

Philosophers from Early modern period

Desiderius Erasmus, 1466 AD

He was an Humanist philosopher (a philosophy that Humans have more importance rather than divine or supernatural matters). His most famous book is the "In praise of Folly", which is a satirical attack on superstitions, various religious prejudice and traditions of European society, and on the Latin Church. This work had an important role in the beginnings of the Protestant reformation.

Niccolo Machiavelli, 1469 AD

He is most notably known for "The Prince" book. In this book he advises an imaginary prince about statecraft and politics. Such books are not new and dates back to the ancient times, but what makes Machiavelli's work different is that instead of advising the prince to acquire royal moral virtues, he advises him to acquire expedient and opportunistic political ethics. His prince should fear not of being blamed for the vices that are necessary for the preservation of the country. He believed that sometimes oppression is better than mercy, and baseness is better than forgiveness.

Although this emphasis on realist politics has brought criticism, he is still revered as the father of modern political philosophy.

Michel de Montaigne, 1533 AD

He was one of the most significant philosophers of the French Renaissance. He popularized essay-writing as a literary genre. Essays were an inner exploration, an attempt to find the roots of personal thoughts on a certain topic. He was self-questioning in moral judgments, and used skeptical questioning in everyday life. In Essays, Montaigne discusses a plethora of topics; cannibalism, education, his relationship with his father, smells, books, cruelty, experience and many others. His essays later influenced William Shakespeare, the famouse English playwright.

About animals, in contrary to René Descartes who believed animals are not more than a set of conditional reflexes (as they don't have rational thinking), Montaigne believed that the relation between humans and animals is two-way: "When I play with my cat, maybe it's them who play with me."

Francis Bacon, 1561 AD

Known as the father of empiricism (the idea that all learning comes from only experience and observations). He was the first philosopher to use a post-Aristotelian method for empirical research. In his "Novum Organum" work he proposes a new scientific approach based on inductive reasoning. He wanted fully scientific approaches based on observation and experience to improve the quality of human life, and to create new technologies with the support of the government (as we later see in the Industrial Revolution). He recreated these ideas in the form of a story in his utopian novel "The New Atlantis".

Thomas Hobbes, 1588 AD

He was famous for his political philosophy in his book "Leviathan", and a radical and pessimistic materialist, who believed that only authoritarian governments can save mankind from the evil consequences of its human nature. This political view of his formed by the turbulent political conditions of his time. Influenced by European thinkers who started the scientific revolution, as well as close acquaintance with the French mathematician and astronomer Pierre Gassendi and the Italian physicist Galileo Galilei, he became convinced that there is nothing but matter in motion.

René Descartes, 1596 AD

Cogito ergo sum (I think, therefore I am). René Descartes is known as the father of the modern philosophy, and a pioneering scientist and mathematician. He founded the view of rationalism, and believed that reason is the key to understanding the universe.

He used skepticism as a tool. He believed that everything we believe through the perception of our senses is not reliable. We cannot even be sure whether we are asleep or awake, but according to the claim "I think therefore I am", the only thing that cannot be doubted is that the doubter exists. This was later known as the Cartesian Doubt.

If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things

— René Descartes

Blaise Pascal, 1623 AD

He was an extraordinary talented person in the field of mathematics to practical inventions, however, his focus was on his spiritual quest. He propagated a religious doctrine that taught the experience of God through the heart rather than through reason, although
in his Pensées (1657–58), Pascal applied elements of game theory to show that belief in the Christian religion is rational.

Baruch Spinoza, 1632 AD

He studied the philosophy of the philosophers who came before him specially Blaise Pascal and Thomas Hobbes. According to Descartes there are only three substances in the world: God, mind, and body. But Spinoza could not accept the absolute distinction between mind and body. His solution was absolute monism instead of Descartes' dualism: Mind and body and all their manifestations were only transformations of a single substance, the substance that creates the world and that is God.

In the field of religion and the holy book, Spinoza believed that readers of the holy book should interpret the text in their own language and terms, regardless of the existing teachings.

In his "Ethics, Demonstrated in Geometrical Order", he believed that his absolute monism view has moral consequences. If only one substance exists and that is God, then everything that happens is a temporarily change in the shape of that substance. This change of shape can appear in both forms of mind and body, therefore God is always beyond our understanding. Spinoza does not draw pessimistic conclusions from these assumptions. For example, he does not say that if we are not able to understand God, then our efforts are in vain, but we should try to get closer to God by increasing our knowledge.

John Locke, 1632 AD

John Locke's works established the basis of political liberalism and philosophical empiricism and influenced many things from the American Constitution to Berkeley's and Hume's thoughts.

In his "An Essay Concerning Human Understanding", He disagreed with rationalists such as Descartes. He argued that humans are not born with innate knowledge and perception is achieved through experience. He believed that we are a "tabula rasa" (Latin: “scraped tablet”—i.e., “clean slate”) at birth: empty, but receptive to the experiences that happen to us in life.

In his greatest political work, "Two Treatises of Government", he argued against absolute monarchy, and explained his thoughts on the social contract, the will of the majority, the equality of human beings, and the duties and limits of a legitimate government.

Gottfried Wilhelm Leibniz, 1646 AD

Known as the Aristotle of the modern world, he was a thinker who wanted to fill the gap between the God-centered world and the rationalism caused by the scientific revolution, and was one of the two thinkers who invented differential and integral calculus.

He was always careful not to upset his employers, and therefore only published works that he knew would not cause great outrage. As an example, in his "Theodicy" he argued that among the infinite number of possible worlds that could have been created, God as the Absolute Being created the best. To explain the existence of evil in the best possible world, he claimed that a world with free will that makes even evil actions possible is better than a forced world without free will.

In his "Monadology", he uses the term "Monas" (or units) to explain the fundamental elements of existence. He believed that the world is made up of many Monas. New readers compare this concept with atoms, but Leibniz considered each of these Monas to be a separate and independent small world, so that each of them reflects the entire universe. He also used the term "Vis Viva" as an attempt to describe the amount of motion, which today is known as Kinetic Energy.

Juana Inés de la Cruz, 1651 AD

She was a poet, scholar, dramatist, and a nun who devoted her life to scientific and philosophical studies and the creation of literary works, and in recent years, she is known as one of the symbols of feminism.

In her "Respuesta a Sor Filotea" (Reply to Sister Fiotella) she argued that throughout the Bible there is no trace of the prohibition of education for women, and on the other hand, education can increase women's understanding of religious texts. However, the church authorities were critical of her activities, and the archbishop of Mexico, who was an opponent of the theater, accused her of disobedience. Due to these pressures, she was forced to leave her interests and had to sign her penance letter with her own blood. She finally sold all her books and scientific equipment and gave the money to the poor.

George Berkeley, 1685 AD

He was a priest and philosopher who proposed the concept of Subjective Idealism and believed that material objects exist only in the form of perception.

He felt dissatisfied with John Locke's materialistic implications. John Locke believed that objects enter our consciousness through sensory organs and when this sensory stimulation enters our consciousness, thought is produced in the mind. Berkeley was against this logic that could undermine the reasons for God's existence. He considered Locke's world to be a world that could act completely on its own without divine intervention. In such a world, the whole morality is at risk as there is no God.

Berkeley believed that the only reality we can be sure of is the one inside our mind. Our real world is the imagination we create in our mind. He went so far as to claim that material objects do not exist as long as they are not the direct object of our perception. If he were asked, "Does that table exist when no one is in the room?" He would say: "That table is always there because God is always looking at it."

Voltaire, 1694 AD

Voltaire was one of the key figures of the rationalism of the Age of Enlightenment and one of the founders of the modern liberal tradition. He was devoted to freedom of speech and thought, and a critic of the authority of religion and government.

Influenced by John Locke's liberal philosophy, Isaac Newton's science, and the freedom of speech and religious tolerance of Britain, in his book entitled "Letters on the English", he praised the opponents of religion, Locke's theory of knowledge based on evidence, and the freedom of science from religious prejudices. This book was banned, denounced and burned because of its anti-Catholic tendencies in Voltaire's place of birth, France.

After the torture and execution of a French Protestant who was wrongly accused of murder, he wrote the "Treatise on Tolerance" and defended Deism (a belief in the existence of God, specifically in a creator who does not intervene in the universe after creating it, solely based on rational thought without any reliance on revealed religions or religious authority).

More philosophers from Early modern period

If you're interested you can read about more philosophers of the early modern period:

To be continued

I'll cover more philosophers from the Modern era, 20th century, and Today's world in the Part 2 of this blog post. Philosophers including but not limited to people like David Hume, Immanuel Kant, Friedrich Hegel, Karl Marx, Bertrand Russell, Martin Heidegger, Karl Popper, Michel Foucault, and many more.



  1. It's actually in debate if he is really the author of the book (or if he even existed at all).

  2. Analects is actually gathered by the students of Confucius (or maybe the students of his students).

  3. Qi is a pseudoscientific, unverified concept, and is unrelated to the concept of energy used in science.