Pre-Socratic philosophy

[5] Scholar André Laks [fr] distinguishes two traditions of separating pre-Socratics from Socratics, dating back to the classical era and running through current times.

The first tradition is the Socratic-Ciceronian, which uses the content of their philosophical inquires to divide the two groups: the pre-Socratics were interested in nature whereas Socrates focused on human affairs.

The knowledge we have of the pre-Socratics derives from the accounts of later writers such as Plato, Aristotle, Plutarch, Diogenes Laërtius, Stobaeus, and Simplicius, and some early Christian theologians, especially Clement of Alexandria and Hippolytus of Rome.

A similar way of referring to quotes is the system prefixed with "LM" by André Laks and Glenn W. Most who edited Early Greek Philosophy in 2016.

The pre-Socratic era lasted about two centuries, during which the expanding Persian Achaemenid Empire was stretching to the west, while the Greeks were advancing in trade and sea routes, reaching Cyprus and Syria.

Ionian towns, especially Miletus, had close trade relations with Egypt and Mesopotamia, cultures with observations about the natural world that differed from those of the Greeks.

While long-distance communication was difficult during ancient times, persons, philosophers, and books moved through other parts of the Greek peninsula, the Aegean islands, and Magna Graecia, a coastal area in Southern Italy.

[27] Transmigration of life, a belief of the Orphics, a religious cult originating from Thrace, had affected the thought of the 5th century BC but the overall influence of their cosmology on philosophy is disputed.

[32] They emphasized the rational unity of things and rejected supernatural explanations, seeking natural principles at work in the world and human society.

[33] In their effort to make sense of the cosmos they coined new terms and concepts such as rhythm, symmetry, analogy, deductionism, reductionism, mathematization of nature and others.

This may have been because of a lack of instruments, or because of a tendency to view the world as a unity, undeconstructable, so it would be impossible for an external eye to observe tiny fractions of nature under experimental control.

The first phase of pre-Socratic philosophy, mainly the Milesians, Xenophanes, and Heraclitus, consisted of rejecting traditional cosmogony and attempting to explain nature based on empirical observations and interpretations.

[41] The pre-Socratics were succeeded by the second phase of ancient philosophy, where the philosophical movements of Platonism, Cynicism, Cyrenaicism, Aristotelianism, Pyrrhonism, Epicureanism, Academic skepticism, and Stoicism rose to prominence until 100 BC.

They were mainly occupied with the origin and substance of the world; each of them attributed the Whole to a single arche (beginning or principle), starting the tradition of naturalistic monism.

[58] In response to Thales, he postulated as the first principle an undefined, unlimited substance without qualities (apeiron), out of which the primary opposites, hot and cold, moist and dry, became differentiated.

[59] According to Giorgio de Santillana, a philosophy professor at the Massachusetts Institute of Technology, Anaximander's conception of a universe governed by laws shaped the philosophical thinking of centuries to come and was as important as the discovery of fire or Einstein's breakthroughs in science.

Anaximenes took for his principle aēr (air), conceiving it as being modified, via thickening and thinning, into the other classical elements: fire, wind, clouds, water, and earth.

While his theory resembled that of Anaximander, as they both claimed a single source of the universe, Anaximenes suggested sophisticated mechanisms in which air is transformed to other elements, mainly because of changes of density.

Alcmaeon noticed that most organs in the body come in pairs and suggested that human health depends on harmony between opposites (hot/cold, dry/wet), and illness is due to an imbalance of them.

As Carl A. Huffman notes, Plato had a tendency to invoke mathematics in explaining natural phenomena, and he also believed in the immortality, even divinity of the human soul.

[90] It tells a story of a young man (kouros in ancient Greek) dedicated to finding the truth carried by a goddess on a long journey to the heavens.

They attacked traditional thinking, from gods to morality, paving the way for further advances of philosophy and other disciplines such as drama, social sciences, mathematics, and history.

The narrative of their thought contributed to shifting the course of ancient Greek philosophy and religion away from the realm of divinity and even paved the way for teleological explanations.

[136] They attacked the traditional representations of gods that Homer and Hesiod had established and put Greek popular religion under scrutiny, initiating the schism between natural philosophy and theology.

Xenophanes set three preconditions for God: he had to be all good, immortal and not resembling humans in appearance, which had a major impact on western religious thought.

[146] The systematic study of anatomy, physiology, and illnesses led to the discovery of cause-effect relations and a more sophisticated terminology and understanding of the diseases that ultimately yielded rational science.

[155] The pre-Socratic intellectual revolution is widely considered to have been the first step towards liberation of the human mind from the mythical world and initiated a march towards reason and scientific thought that yielded modern western philosophy and science.

Whether arche meant the beginning, the origin, the main principle or the basic element is unclear, but was the first attempt to reduce the explanations of the universe to a single cause, based on reason and not guided by any sort of divinity.

[179] The pre-Socratics, along with the rest of ancient Greece, invented the central concepts of Western civilization: freedom, democracy, individual autonomy and rationalism.

He criticized the pre-Socratic theory of knowledge by Xenophanes and others, claiming that their deductive reasoning could not yield meaningful results—an opinion contemporary philosophy of science rejects.