Pre-Socratic philosophy in the context of "Poleis"

Western philosophy refers to the philosophical thought, traditions, and works of the Western world. Historically, the term refers to the philosophical thinking of Western culture, beginning with the ancient Greek philosophy of the pre-Socratics. The word philosophy itself originated from the Ancient Greek φιλοσοφία (philosophía), literally, 'the love of wisdom', from Ancient Greek: φιλεῖν (phileîn), 'to love', and σοφία (sophía), 'wisdom'.

Western philosophy stands in contrast to other cultural and regional traditions like Eastern philosophy.

Flat Earth is an archaic and scientifically disproven conception of the Earth's shape as a plane or disk. Many ancient cultures subscribed to a flat-Earth cosmography. The model has undergone a recent resurgence as a conspiracy theory in the 21st century.

The idea of a spherical Earth appeared in ancient Greek philosophy with Pythagoras (6th century BC). However, the early Greek cosmological view of a flat Earth persisted among most pre-Socratics (6th–5th century BC). In the early 4th century BC, Plato wrote about a spherical Earth. By about 330 BC, his former student Aristotle had provided strong empirical evidence for a spherical Earth. Knowledge of the Earth's global shape gradually began to spread beyond the Hellenistic world. By the early period of the Christian Church, the spherical view was widely held, with some notable exceptions. In contrast, ancient Chinese scholars consistently describe the Earth as flat, and this perception remained unchanged until their encounters with Jesuit missionaries in the 17th century. Muslim scholars in early Islam maintained that the Earth is flat. However, since the 9th century, Muslim scholars have tended to believe in a spherical Earth.

Heraclitus (/ˌhɛrəˈklaɪtəs/; Ancient Greek: Ἡράκλειτος Hērákleitos; fl. c. 500 BC) was an ancient Greek pre-Socratic philosopher from the city of Ephesus, which was then part of the Persian Empire. He exerts a wide influence on Western philosophy, both ancient and modern, through the works of such authors as Plato, Aristotle, Georg Wilhelm Friedrich Hegel, Friedrich Nietzsche, and Martin Heidegger.

Little is known of Heraclitus's life. He wrote a single work, of which only fragments survive. Even in ancient times, his paradoxical philosophy, appreciation for wordplay, and cryptic, oracular epigrams earned him the epithets "the dark" and "the obscure". He was considered arrogant and depressed, a misanthrope who was subject to melancholia. Consequently, he became known as "the weeping philosopher" in contrast to the ancient atomist philosopher Democritus, who was known as "the laughing philosopher".

Parmenides of Elea (/pɑːrˈmɛnɪdiːz ... ˈɛliə/; Ancient Greek: Παρμενίδης ὁ Ἐλεάτης; fl. late sixth or early fifth century BC) was a pre-Socratic Greek philosopher from Elea in Magna Graecia (Southern Italy).

Parmenides was born in the Greek colony of Elea to a wealthy and illustrious family. The exact date of his birth is not known with certainty; on the one hand, according to the doxographer Diogenes Laërtius, Parmenides flourished in the period immediately preceding 500 BC, which would place his year of birth around 540 BC; on the other hand, in the dialogue Parmenides Plato portrays him as visiting Athens at the age of 65, when Socrates was a young man, c. 450 BC, which, if true, suggests a potential year of birth of c. 515 BC. Parmenides is thought to have been in his prime (or "floruit") around 475 BC.

Protagoras (/proʊˈtæɡərəs, -æs/ proh-TAG-ər-əs, -⁠ass; Greek: Πρωταγόρας; c. 490 BC – c. 420 BC) was a pre-Socratic Greek philosopher and rhetorical theorist. He is numbered as one of the sophists by Plato. In his dialogue Protagoras, Plato credits him with inventing the role of the professional sophist.

Protagoras is also believed to have created a major controversy during ancient times through his statement that "Of all things the measure is Man, of the things that are, that they are, and of the things that are not, that they are not" which was usually rendered simply as "Man is the measure of all things," interpreted (possibly wrongly, since he disagreed) by Plato to mean that there is no objective truth; Protagoras seems to have meant that each person's own personal history, experiences and expectations, developed over their lifetime, determine their judgments, opinions, and statements regarding "truth" (which is the title of the book in which Protagoras made this statement). When a person makes a judgment about a certain thing—good or bad or beautiful or unjust—that person will differ from other people's judgments because their experience has been different.

Natural law (Latin: ius naturale, lex naturalis) is a philosophical and legal theory that posits the existence of a set of inherent laws derived from nature and universal moral principles, which are discoverable through reason. In ethics, natural law theory asserts that certain rights and moral values are inherent in human nature and can be understood universally, independent of enacted laws or societal norms. In jurisprudence, natural law—sometimes referred to as iusnaturalism or jusnaturalism—holds that there are objective legal standards based on morality that underlie and inform the creation, interpretation, and application of human-made laws. This contrasts with positive law (as in legal positivism), which emphasizes that laws are rules created by human authorities and are not necessarily connected to moral principles. Natural law can refer to "theories of ethics, theories of politics, theories of civil law, and theories of religious morality", depending on the context in which naturally-grounded practical principles are claimed to exist.

In Western tradition, natural law was anticipated by the pre-Socratics, for example, in their search for principles that governed the cosmos and human beings. The concept of natural law was documented in ancient Greek philosophy, including Aristotle, and was mentioned in ancient Roman philosophy by Cicero. References to it are also found in the Old and New Testaments of the Bible, and were later expounded upon in the Middle Ages by Christian philosophers such as Albert the Great and Thomas Aquinas. The School of Salamanca made notable contributions during the Renaissance.

The Ionian school of pre-Socratic philosophy refers to Ancient Greek philosophers, or a school of thought, in Ionia in the 6th century BC, the first in the Western tradition.

The Ionian school included such thinkers as Thales, Anaximander, Anaximenes, Heraclitus, Anaxagoras, and Archelaus. This classification can be traced to the doxographer Sotion. The doxographer Diogenes Laërtius divides pre-Socratic philosophy into the Ionian and Italian school. The collective affinity of the Ionians was first acknowledged by Aristotle who called them physiologoi (φυσιολόγοι), or natural philosophers. They are sometimes referred to as cosmologists, since they studied stars and maths, gave cosmogonies and were largely physicalists who tried to explain the nature of matter.

Thales of Miletus (/ˈθeɪliːz/ THAY-leez; Ancient Greek: Θαλῆς; c. 626/623  – c. 548/545 BC) was an Ancient Greek pre-Socratic philosopher from Miletus in Ionia, Asia Minor. Thales was one of the Seven Sages, founding figures of Ancient Greece.

Beginning in eighteenth-century historiography, many came to regard him as the first philosopher in the Greek tradition, breaking from the prior use of mythology to explain the world and instead using natural philosophy. He is thus otherwise referred to as the first to have engaged in mathematics, science, and deductive reasoning.

Anaximander (/æˌnæksɪˈmændər/ an-AK-sih-MAN-dər; Ancient Greek: Ἀναξίμανδρος Anaximandros; c. 610 – c. 546 BC) was a pre-Socratic Greek philosopher who lived in Miletus, a city of Ionia (in modern-day Turkey). He belonged to the Milesian school and learned the teachings of his master Thales. He succeeded Thales and became the second master of that school, where he counted Anaximenes and, arguably, Pythagoras amongst his pupils.

Little of his life and work is known today. According to available historical documents, he is the first philosopher known to have written down his studies, although only one fragment of his work remains. Fragmentary testimonies found in documents after his death provide a portrait of the man.