Ancient Greek Philosophy coverds two periods: Hellenic and Hellenistic Roman.
Hellenic philosophy; It starts with Thales and continues until 322 BC, when Aristotle died. It can be considered in three periods;
1- Presocratic philosophy (naturalistic period, philosophy of nature)
2- Socratic philosophy or Philosophy on Man
3- Systematic Period or Great Socratics (Plato, Aristotle).
Hellenistic-Roman philosophy; It starts in the last quarter of the 4th century BC and continues until the 6th century AD. It can be divided into two periods;
1- Hellenistic age; 322 BC-AD 331; Stoic, Epicurean and Skeptic schools.
2- Roman philosophy.
THALES (625-547 BC)
The philosophical movement founded by Thales, Anaximander and Anaximenes in the city of Miletos, which is within the borders of Manisa province today, is known as the Milesian School. Although the concepts of idealism and materialism were not yet used in the era they lived in, they are considered the first materialists in the history of philosophy. The main object of thinking in this school was “arche”, which refers to the thing from which everything is created and derived.
Thales, who is considered the first philosopher, questioned what really existed behind the visible multitude. He suggested that arche was water and that everything was created from water. Moreover, the water presented as arche was not an unnatural entity or cause but something that was already found in nature. Water had life and this idea is called living materialism (hylozoism). Life requires a soul and everything is full of gods. Nature is a self-regulating system that does not require external intervention.
Thales was a scientist as well as a philosopher, which is a characteristic of the era. He became the founder of geometry by transforming the knowledge of geometry he received from Egypt from a practical benefit purpose to a theoretical basis. Thales' theorem belongs to him; the diameter of the circle divides the circle into two equal parts and the base angles of an isosceles triangle are equal. He also made many observations celestial events, maritime astronomy and mathematics.
ANAXIMANDROS (611-546 BC)
Anaximandros a student of Thales, identified apeiron as arkhe. Apeiron is an abstract structure that is infinite in quantity and uncertain in quality. It contains opposites together and is the source of movement and order. It was not only considered as something from which everything that exists originates and returns to itself, but also as the general law of the struggle between opposites that prevails in the universe.
Anaximandros , who was also interested in astronomy, cartography and mathematics, discovered the ecliptic curvature of the world and the sundial. He made maps of the earth and the sky centered on the Mediterranean. He stated that life began in the seas and later came to land.
ANAXIMENES (585-525 BC)
Anaximenes suggested that arkhe was air. Air both has a material and finite structure and is also endless and infinite. Air expands and turns into fire, condenses and turns into soil and water. Thus, he sought a solution to the problem of formation by trying to explain for the first time how other things came into being from arkhe.
Based upon his studies on astronomy, he determined that the only real source of light was the sun, and he also correctly explained solar and lunar eclipses.
PYTHAGORAS (570-495 BC)
According to Pythagoras, who established a political union similar to a sect in Croton in the south of Italy, philosophy is a way of life. The aim of the teaching, which was influenced by the Orphic movement and the belief in transmigration of souls, was to purify, tounite with the spirit of the universe, and get out of the cycle of rebirth. The body is the prison of the soul. The body is evil and the soul needs to be freed from the body. For this purpose, certain rituals were performed. Newcomers were forbidden from asking questions for the first few years, students were asked to develop a foundaton of learning , and music, mathematics, astronomy and medicine were taught. There were also strange rules such as not eating beans and meat, and not stirring fire with iron.
According to Ptythagoras, there are 3 types of people: those who pursue fame and reputation; those who pursue material things; and those who pursue knowledge. An understanding of the divine universe brings a person closer to the universal spirit. Opposites should be met in harmony. The microcosm of man and the macrocosm of the universe know each other, like knows like .
According to Pythagoras, everything is made up of quantities and numbers. This means that we can understand the universe with mathematical expressions. If everything is made up of numbers, its order is also connected to a knowledge that measures quantities. The most fundamental concept of Pythagorean thought is "harmonia".
Pythagoras has made many mathematical and scientific contributions such as the Pythagorean theorem (the square of the hypotenuse in a right-angled triangle is equal to the sum of the squares of the other two sides), the theory of proportions, the sphericity of the world, and the identity of the morning and evening stars with Venus.
HERACLEITOS (535-457 BC)
Heracleitos's doctrine of logos tries to explain the phenomenon of change in nature. According to Heraclitus, he found a kind of unity or integrity among all changes and oppositions in nature. He called this law underlying everything "God" or "Logos". The equivalent of logos in nature is reason in humans.
According to Heraclitus, it is important to know deeply, not to accumulate knowledge. Knowledge conveyed by others or acquired through the senses is valuable if it is carefully criticized and interpreted in the person's own comprehension processes, and wisdom can only be achieved in this way. Aisthesis in humans enables physical contact with the universe through the sense organs, and noesis enables the processing of acquired sense data. The aim of humans should be to understand the law of logos and live according to it.
Heraclitus chooses arkhe as fire, fire is a principle that leads to the qualitative change of everything. Logos, God, Cosmos, Fire (Pyr) are identical.
It is the war of opposites found in the object that creates change. There is not only the war of these opposites but also their unity. Continuous change leads us to his teaching of flow. Everything changes. "We cannot step into the same river twice", when I step into the river a second time, I have changed and so has the river.
Good and bad, beautiful and ugly, everything must be grasped in unity by rising above these opposites. When you can look at the universe like this, everything is good, everything is beautiful.
Man must conform to the flow of the universe and exercise his mind in harmony with virtues such as wisdom, justice, moderation and bravery.
PARMENIDES (515-460 BC);
The philosophy put forward by Parmenides is called Eleatic philosophy, because he lived in the region of Italy called Elea. According to Parmenides, who rejected change and movement, being does not change, does not divide, does not move, was not born and will not die.
According to Parmenides, change is only a deception of the senses. Being does not come from nothing, and nothingness does not come from being. Nothing comes from nothing. According to Parmenides, appearance is sensory and deceptive. If a person turns to the universe with his mind and not with his senses, he grasps reality. According to Parmenides, only being can be thought of, nothingness cannot be conceived of, there is no void in the universe and thought and reality are identical.
ZENON (490-430 BC)
Zenon tries to prove the thesis of Parmenides with his paradoxes. There are paradoxes related to multiplicity and paradoxes related to movement. In the Achilles paradox, the demigod Achilles and the tortoise compete. He claims that he will never catch up because the tortoise will cover a further distance with each advance of Achilles.
XENOPHANES (570-478 BC)
Xenophanes is considered the patriarch of theoria. Questions such as the source of knowledge, the criterion of truth and its scope begin with Xenophanes. A distinction must be made between knowledge and non-knowledge. According to him, the limit of knowledge is our experiences. He describes everything else as opinion.
He criticized the anthropomorphic understanding of god. These criticisms are in line with the understanding of a single god (Monotheism), but his god is a semi-concrete, semi-abstract, spherical, corporeal god. According to him, gods can not be not spoken about in the world of experiences, The human world and the world of gods constitute two separate realities.
PLURALISTS
The philosophers who came after Parmenides and Heraclitus tried to reconcile the opposition of everything changes - nothing changes. They also challenged the the concept of living matter advanced the first natural philosophers.
EMPEDOCLES (492-432 BC)
He was influenced by Orphic and Pythagorean ideas and the theory of reincarnation. Some parts of his work called Purifications are extant today.. His concept of God is like that of Xenophanes. God moves around the universe with his intelligence and quick thoughts.
According to Empedocles, we can only reach knowledge by using the senses and reason together. Heraclitus and Parmenides are both right. Earth, water, air and fire (the four elements) do not change, Love and hate mix and separate these four elements. Reality does not change, the apparent change is the result of the arrangement and displacement of the four elements. The cycle of cosmos period dominated by love and the chaos dominated by hatred continue forever in the universe.
ANAXAGORAS (498-428 BC)
According to Anaxagoras, everything is formed from small seeds (spermata). Spermata are infinite in number and immortal. Change occurs with the joining together and separation of spermata. Nous organizes these changes. The universe consists of spermata and Nous. Everything has a share of other things. Chaos refers to everything being everywhere. Nous plans and realizes change and movement for a purpose (teleology, purpose). Man has a share of Nous.
Perceiving means choosing and separating, it necessitates the existence of opposition, not similarity. Knowledge is the result of oppositions.
Anaxagoras was critical of the religious tradition of the period. He was the first philosopher to be accused of atheism, tried and sentenced to death, and escaped from Athens.
DEMOCRITUS (460-371 BC)
According to Democritus of Macedonia, the universe consists of atoms and a limitless void. Atoms have not been created, they are eternal, they do not break down, and do not contain voids, they are infinite in number and shape. Atoms can combine to form compound structures that will later disappear. Atoms occupy space. The weight, density and hardness of the atom are its primary qualities, while qualities such as sound, temperature and color are secondary ones.
The soul and God are also structures made up of atoms. They disintegrate after death, and since gods live longer, people think that gods are immortal.
Democritus adopts mechanical materialism. Since he argues that the essential feature of matter is motion, there is no need for an active causal agent to set the matter in motion. All events are action and reaction relationships between atoms. Causality is an expression of the necessity that prevails in the universe. When people cannot solve the causal relationship, they talk about coincidences.
Democritus believed that wisdom would make people happy. Life should be lived wisely, moderately and balancedly. The purpose of morality is to endow people with spiritual serenity (euthymia). Thinking correctly, speaking correctly and acting correctly create spiritual serenity. He uses various concepts to define spiritual serenity; eusteo (well-being), athambia or athaumastia (absence of admiration), ataraxia (tranquility), harmonia (harmony), summetria (symmetry) and cudaemonia (happiness). To be happy, it is necessary to get rid of empty fears and delusions, especially the fear of death.
SOPHISTS
A great philosophical transformation took place after the atomist philosophy. Philosophers turned their attention to humans; the anthropological period. The rising commercial rich, who needed a new philosophy, opened the era of the Sophists. Sophists gave lessons on politics, effective rheotircs in speech , as well as astronomy, mathematics, and music for a fee. The definition of Sophist is also used as an adjective indicating the competence of the person in his/her field.
According to Protagoras (481-411 BC), "Man is the measure of all things." Justice and injustice, good and evil should always be evaluated according to human needs. Every subject is relative. Man acquires knowledge through his/her experiences, his/her knowledge is based on the cooperation of experience and reason, and is limited. Another claim of equal strength can be made against each claim, and these two claims can be of equal validity.. These skeptical approaches bring Protagoras closer to agnosticism. He states that it can not be known whether gods exist or not. We cannot reach the truth through the senses or reason. The criterion of knowledge is its success in application (praxis). Knowledge should provide solutions to practical problems and convince people. Everyone can be educated and virtuous to a certain extent.
According to Gorgias (483-375 BC), nothing exists, even if it does, it cannot be known, and even if it is known, it cannot be conveyed to others. Data about an object is obtained through the senses, but we try to express this data in words. Since language is different from our senses, it cannot represent them accurately.
According to Prodicus (465-399 BC), people's attitudes towards religious and divine issues are shaped according to their relationships with beings in nature. People deify the things they value in nature.
According to Hippias (460-399 BC), people are naturally equal.
According to Antiphon, people should act according to the law when in public, and according to the dictates of their own nature when alone.
According to Thrasymachus (459-400 BC), nature and law are opposites, inequality between people is natural and the rule of the strong over the weak is also natural.
According to Callicles, people cowardly glorify many things that are contrary to their nature. In contrast, they should exalt their ambitions as much as possible and live without supprssing any of them.
According to Lykhophron, in natural life, it is good to be unjust to others and but to be subjected to injustice.
Critias (460-403 BC) argues that religion and divine issues are invented by intelligent people so that people will obey the laws.
Theognis asserts that the knowledge of government is innate.