Editing Pre-Socratic philosophy (section)

== Pre-Socratic philosophers ==
[[Image:Presocratic graph.svg|thumb|right|300px|Graphical relationship among the various pre-socratic [[philosopher]]s and [[Intellectual|thinker]]s; red arrows indicate a relationship of opposition.]]

===Milesian beginning: Thales, Anaximander and Anaximenes===

The [[Milesian school]] was located in [[Miletus]], Ionia, in the 6th century BC. It consisted of [[Thales]], [[Anaximander]], and [[Anaximenes of Miletus|Anaximenes]], who most probably had a teacher-pupil relationship. 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.{{sfnm|1a1=Sandywell|1y=1996|1pp=75-78|2a1=Kirk|2a2=Raven|2y=1977|2p=73}}

====Thales====
{{Main|Thales}}
[[Image:Thales' Theorem Simple.svg|thumb|left|alt=Illustration of Thales' theorem |Thales's theorem: if {{overline|AC}} is a diameter and B is a point on the diameter's circle, the angle ABC is a right angle.]]
Thales ({{circa}} 624–546 BC) is considered to be the father of philosophy.{{sfnm|1a1=Barnes|1y=1987|1p=36|2a1=Warren|2y=2014|2p=23}} None of his writings have survived. He is considered the first western philosopher since he was the first to use reason, to use proof, and to generalize. He created the word ''cosmos'', the first word to describe the universe. He contributed to [[geometry]] and predicted the [[Eclipse of Thales|eclipse of 585 BC]].{{sfn|Sandywell|1996|p=86}} Thales may have been of [[Phoenicia|Phoenician ancestry]].{{sfnm|1a1=Sandywell|1y=1996|1p=89|2a1=Kirk|2a2=Raven|2y=1977|2pp=74-75}} Miletus was a meeting point and trade centre of the then great civilizations, and Thales visited the neighbouring civilizations, Egypt, Mesopotamia, Crete, and Phoenicia.{{sfn|Sandywell|1996|p=89}} In Egypt, geometry was advanced as a means of separating agricultural fields. Thales, though, advanced geometry with his abstract [[deductive reasoning]] reaching [[Generalization|universal generalizations]]. [[Proclus]], a later Athenian philosopher, attributed the theorem now known as [[Thales's theorem]] to Thales. He is also known for being the first to claim that the base angles of [[isosceles triangle]]s are equal, and that a [[diameter]] bisects the [[circle]].{{sfn|Sandywell|1996|p=87}} Thales visited [[Sardis]], as many Greeks then, where astronomical records were kept and used astronomical observations for practical matters (oil harvesting).{{sfn|Sandywell|1996|pp=86, 90}} Thales was widely considered a genius in ancient times{{sfn|Sandywell|1996|p=90}} and was revered as one of the [[Seven Sages of Greece]].{{sfn|Warren|2014|p=28}}

Most importantly, what marks Thales as the first philosopher is the posing of the fundamental philosophical question about the origin and the substance of the world, while providing an answer based on [[empirical evidence]] and reasoning. He attributed the origin of the world to an element instead of a divine being.{{sfn|Sandywell|1996|p=93}} Our knowledge of Thales' claim derives from Aristotle. Aristotle, while discussing opinions of previous philosophers, tells us that "Thales, the founder of this type of philosophy, says the principle (arche) is water." What he meant by arche, is a matter of interpretation (it might be the origin, the element, or an ontological matrix), but regardless of the various interpretations, he conceived the world as One thing instead of a collection of various items and speculated on the binding/original elements.{{sfn|Sandywell|1996|p=90-94}}

Another important aspect of Thales' philosophy is his claim that everything is full of gods. What he meant by that is again a matter of interpretation, that could be from a theistic view to an atheist one.{{sfn|Sandywell|1996|p=94-96}} But the most plausible explanation, suggested by Aristotle, is that Thales is advocating a theory of [[hylozoism]], that the universe, the sum of all things that exist, is divine and alive.{{sfn|Sandywell|1996|p=97}} Lastly, another notable claim by Thales is that earth "rests on water"- maybe that was a conclusion after observing fish fossils on land.{{sfnm|1a1=Sandywell|1y=1996|1pp=97-98|2a1=Warren|2y=2014|2p=27}}

====Anaximander====
{{Main|Anaximander}}

{{Quote box
 |quote  =<poem>That from which all things are born
the beginning of all things
the first foundation of things is the Unlimited (apeiron);
The source from which coming-to-be is, for things that are, and for
their passing away in accordance with necessity.
For they give justice and pay retribution to each other for their mutual
injustice according to the ordered process of time.</poem>
 |author = [[Anaximander]], DK 12 B 1
 |source = preserved fragment of ''On Nature''{{sfn|Sandywell|1996|p=139}}
 |width  = 33em
 |align  = right
}}

Anaximander (610–546 BC), also from Miletus, was 25 years younger than Thales. He was a member of the elite of Miletus, wealthy and a statesman. He showed interest in many fields, including mathematics and geography. He drew the first map of the world, was the first to conclude that the earth is spherical, and made instruments to mark time, something like a clock.{{sfn|Sandywell|1996|pp=136-138}} In response to Thales, he postulated as the first principle an undefined, unlimited substance without qualities (''[[Apeiron (cosmology)|apeiron]]''), out of which the primary opposites, hot and cold, moist and dry, became differentiated. His answer was an attempt to explain observable changes by attributing them to a single source that transforms to various elements. Like Thales, he provided a naturalistic explanation for phenomena previously given supernatural explanations. He is also known for speculating on the origin of mankind. He proclaimed that the earth is not situated in another structure but lies unsupported in the middle of the universe. Further, he developed a rudimentary evolutionary explanation for biodiversity in which constant universal powers affected the lives of animals.{{sfnm|1a1=Barnes|1y=1987|1pp=36-37|2a1=Warren|2y=2014|2pp=28-33}} 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.{{sfn|Sandywell|1996|p=141}}

====Anaximenes====
{{Main|Anaximenes of Miletus}}

Little is known of Anaximenes' (585–525 BC) life. He was a younger contemporary and friend of Anaximander, and the two worked together on various intellectual projects. He also wrote a book on nature in prose. Anaximenes took for his principle ''aēr'' (air), conceiving it as being modified, via thickening and thinning, into the other [[classical element]]s: 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. Since the classical era, he was considered the father of naturalistic explanations. Anaximenes expanded Anaximander's attempt to find a unitary cause explaining natural phenomena both living and nonliving, without, according to James Warren, having to "reduce living things in some way to mere locations of material change".{{sfnm|1a1=Warren|1y=2014|1pp=33-37|2a1=Sandywell|2y=1996|2pp=172-173}}

=== Xenophanes ===
{{Main|Xenophanes}}
[[File:Elmo's fire-2.jpg|thumb|alt=See caption|St. Elmo's fire (luminous plasma created by a corona discharge from a rod-like object) in a ship. Xenophanes' contemporaries attributed this phenomenon to the deity [[Castor and Pollux|Dioscuri]]. Xenophanes argued that the observed illumination is due to small clouds influenced by special circumstances relating to stars—an example of [[Metaphysical naturalism|naturalism]] and [[reductionism]].{{sfn|Mourelatos|2008|pp=134-135}}]]

Xenophanes was born in [[Colophon (city)|Colophon]], an Ionian town near Miletus. He was a well-traveled poet whose primary interests were [[theology]] and [[epistemology]]. Concerning theology, he pointed out that we did not know whether there was one god or many gods, or in such case whether there was a hierarchy among them. To critique the anthropomorphic representation of the gods by his contemporary Greeks, he pointed out that different nations depicted their gods as looking like themselves. He famously said that if oxen, horses, or lions could draw, they would draw their gods as oxen, horses, or lions. This critique was not limited to the looks of gods but also their behaviour. Greek mythology, mostly shaped by the poets [[Homer]] and [[Hesiod]], attributed moral failures such as jealousy and adultery to the gods. Xenophanes opposed this. He thought gods must be morally superior to humans. Xenophanes, however, never claimed the gods were omnipotent, omnibenevolent, or omniscient.{{sfn|Warren|2014|pp=41-50}} Xenophanes also offered naturalistic explanations for phenomena such as the sun, the rainbow and [[St. Elmo's fire]]. Traditionally these were attributed to divine intervention but according to Xenophanes they were actually effects of clouds. These explanations of Xenophanes indicate empiricism in his thought and might constitute a kind of proto-scientism. Scholars have overlooked his cosmology and naturalism since Aristotle (maybe due to Xenophanes' lack of teleology) until recently but current literature suggests otherwise.{{sfn|Mourelatos|2008|pp=134-139}} Concerning epistemology,  Xenophanes questioned the validity of human knowledge. Humans usually tend to assert their beliefs are real and represent truth. While Xenophanes was a pessimist about the capability of humans to reach knowledge, he also believed in gradual progress through critical thinking. Xenophanes tried to find naturalistic explanations for meteorological and cosmological phenomena.{{sfn|Warren|2014|pp=50-56}}

Ancient philosophy historian Alexander Mourelatos notes Xenophanes used a pattern of thought that is still in use by modern metaphysics. Xenophanes, by reducing meteorological phenomena to clouds, created an argument that "X in reality is Y", for example B32, "What they call Iris [the rainbow] that too is in reality a cloud: one that
appears to the eye as purple, red, and green. This is still use[d] today 'lightning is massive electrical discharge' or 'items such as tables are a cloud of micro-particles'." Mourelatos comments that the type of analogy that the cloud analogy is remains present in scientific language and "...is the modern philosopher's favourite subject for illustrations of inter-theoretic identity".{{sfnm|1a1=Mourelatos|1y=2008|pp=136,158-159|2a1=Curd|2y=2020|2loc=Xenophanes of Colophon and Heraclitus of Ephesus}}

According to Aristotle and Diogenes Laertius, [[Xenophanes]] was Parmenides' teacher; but is a matter of debate in current literature whether Xenophanes should also be considered an Eleatic.{{sfn|Warren|2014|p=3}}

===Heraclitus===
{{Main|Heraclitus}}

The hallmark of Heraclitus' philosophy is [[Impermanence|flux]]. In fragment DK B30, Heraclitus writes: ''This world-order [Kosmos], the same of all, no god nor man did create, but it ever was and is and will be: everliving fire, kindling in measures and being quenched in measures''. Heraclitus posited that all things in nature are in a state of perpetual flux. Like previous monist philosophers, Heraclitus claimed that the ''arche'' of the world was fire, which was subject to change – that makes him a [[materialism|materialist]] monist.{{sfn|Graham|2008|pp=170-172}} From fire all things originate and all things return to it again in a process of eternal cycles. Fire becomes water and earth and vice versa. These everlasting modifications explain his view that the cosmos ''was and is and will be''.{{sfn|Graham|2008|pp=170-172}} The idea of continual flux is also met in the "river fragments". There, Heraclitus claims we can not step into the same river twice, a position summarized with the slogan ''ta panta rhei'' (everything flows). One fragment reads: "Into the same rivers we both step and do not step; we both are and are not" (DK 22 B49a). Heraclitus is seemingly suggesting that not only the river is constantly changing, but we do as well, even hinting at [[Existentialism|existential questions about humankind]].{{sfn|Warren|2014|pp=72-74}}

Another key concept of Heraclitus is that opposites somehow mirror each other, a doctrine called [[unity of opposites]]. Two fragments relating to this concept state, "As the same thing in us is living and dead, waking and sleeping, young and old. For these things having changed around are those, and those in turn having changed around are these" (B88) and "Cold things warm up, the hot cools off, wet becomes dry, dry becomes wet" (B126).{{sfn|Graham|2008|p=175}} Heraclitus' doctrine on the unity of opposites suggests that unity of the world and its various parts is kept through the tension produced by the opposites. Furthermore, each polar substance contains its opposite, in a continual circular exchange and motion that results in the stability of the cosmos.{{sfnm|1a1=Sandywell|1y=1996|1pp=263-265|2a1=Graham|2y=2008|2pp=175-177}} Another of Heraclitus' famous axioms highlights this doctrine (B53): "War is father of all and king of all; and some he manifested as gods, some as men; some he made slaves, some free", where war means the creative tension that brings things into existence.{{sfnm|1a1=Sandywell|1y=1996|1pp=263-265|2a1=Curd|2y=2020|2loc= Xenophanes of Colophon and Heraclitus of Ephesus}}

A fundamental idea in Heraclitus is ''[[logos]]'', an ancient Greek word with a variety of meanings; Heraclitus might have used a different meaning of the word with each usage in his book. ''Logos'' seems like a universal law that unites the cosmos, according to a fragment: "Listening not to me but to the logos, it is wise to agree (homologein) that all things are one" (DK 22 B50). While ''logos'' is everywhere, very few people are familiar with it. B 19 reads: [hoi polloi] "...do not know how to listen [to Logos] or how to speak [the truth]".{{sfnm|1a1=Warren|1y=2014|1p=63|2a1=Sandywell|2y=1996|2p=237}} Heraclitus' thought on ''logos'' influenced the [[Stoicism|Stoics]], who referred to him to support their belief that [[Stoic physics|rational law governs the universe]].{{sfn|Warren|2014|p=63}}

=== Pythagoreanism ===
{{Main|Pythagoras}}  
{{See also|Pythagoreanism}}
[[File:Pythagoras in the Roman Forum, Colosseum.jpg|thumb|[[Pythagoras]]]]
[[Pythagoras]] (582–496 BC) was born on [[Samos]], a small island near Miletus. He moved to [[Crotone|Croton]] at about age 30, where he established his school and acquired political influence. Some decades later he had to flee Croton and relocate to [[Metapontum]].{{sfnm|1a1=Barnes|1y=1987|1p=81|2a1=Sandywell|2y=1996|2p=189}}

Pythagoras was famous for studying numbers and the geometrical relations of numbers. A large following of Pythagoreans adopted and extended his doctrine. They advanced his ideas, reaching the claim that everything consists of numbers, the universe is made by numbers and everything is a reflection of analogies and geometrical relations.{{sfnm|1a1=Warren|1y=2014|1p=39|2a1=Sandywell|2y=1996|2p=197}} Numbers, music and philosophy, all interlinked, could comfort the beauty-seeking human soul and hence Pythagoreans espoused the study of mathematics.{{sfn|Sandywell|1996|p=199}}

Pythagorianism perceived the world as perfect harmony, dependent on number, and aimed at inducing humankind likewise to lead a harmonious life, including ritual and dietary recommendations.{{sfn|Curd|2020|loc=The Pythagorean Tradition}} Their way of life was ascetic, restraining themselves from various pleasures and food. They were vegetarians and placed enormous value on friendship.{{sfn|Sandywell|1996|p=192}}  Pythagoras politically was an advocate of a form of [[aristocracy]], a position which later Pythagoreans rejected, but generally, they were reactionary and notably repressed women.{{sfnm|1a1=Curd|1y=2020|1loc=The Pythagorean Tradition|2a1=Sandywell|2y=1996|2pp=192-194}} Other pre-Socratic philosophers mocked Pythagoras for his belief in [[reincarnation]].{{sfn|Warren|2014|p=38}}

Notable Pythagorians included [[Philolaus]] (470-380 BC), [[Alcmaeon of Croton]], [[Archytas]] (428-347 BC) and [[Ecphantus the Pythagorean|Echphantus]].{{sfnm|1a1=Curd|1y=2020|1loc=The Pythagorean Tradition|2a1=Sandywell|2y=1996|2p=195}} The most notable was Alcmaeon, a medical and philosophical writer. 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. He was the first to think of the brain as the center of senses and thinking. Philolaus advanced cosmology through his discovery of heliocentricism – the idea that the Sun lies in the middle of the Earth's orbit and other planets.{{sfn|Sandywell|1996|pp=196-197}}

Pythagoreanism influenced later Christian currents as Neoplatonism, and its pedagogical methods were adapted by Plato.{{sfn|Sandywell|1996|pp=191-192}} Furthermore, there seems to be a continuity in some aspects of Plato's philosophy. 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.{{sfn|Huffman|2008|pp=284-285}}

===The Eleatics: Parmenides, Zeno and Melissus ===
{{Main|Eleatic school}}
The Eleatic school is named after [[Velia|Elea]], an ancient Greek town on the southern Italian Peninsula. [[Parmenides]] is considered the founder of the school. Other eminent Eleatics include [[Zeno of Elea]] and [[Melissus of Samos]]. According to Aristotle and Diogenes Laertius, [[Xenophanes]] was Parmenides' teacher, and it is debated whether Xenophanes should also be considered an Eleatic.{{sfn|Warren|2014|p=3}} Parmenides was born in [[Velia|Elea]] to a wealthy family around 515 BC.{{sfnm|1a1=Barnes|1y=1987|1p=129|2a1=Sandywell|2y=1996|2p=295}} [[Parmenides]] of [[Velia|Elea]] was interested in many fields, such as biology and astronomy. He was the first to deduce that the earth is spherical.{{sfn|Barnes|1987|p=40}} He was also involved in his town's political life.{{sfn|Sandywell|1996|p=295}}

[[File:Being Parmenides.png|thumb|left|upright=0.8|alt=Illustration of a perfect sphere.|According to Parmenides, Being, what exists, is like the mass of a [[perfect sphere]]: undifferentiated, indivisible, and unchangeable.{{sfn|Sandywell|1996|pp=309-310}}]]
Parmenides' contributions were paramount not only to ancient philosophy but to all of western metaphysics and ontology.{{sfn|Sandywell|1996|p=295}} Parmenides wrote a hard to interpret poem, named ''On Nature'' or ''On What-is'', that substantially influenced later Greek philosophy.{{sfnm|1a1=Warren|1y=2014|1p=77|2a1=Barnes|2y=1987|2pp=40-41}} Only 150 fragments of this poem survive.{{sfn|Warren|2014|p=79}} 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. The poem consists of three parts, the [[proem]] (i.e., preface), the ''Way of Truth'' and the ''Way of Opinion''.  Very few pieces from the ''Way of Opinion'' survive. In that part, Parmenides must have been dealing with cosmology, judging from other authors' references.{{sfn|Warren|2014|pp=79-80}} The ''Way of Truth'' was then, and is still today, considered of much more importance. In the ''Way of Truth'', the goddess criticizes the logic of people who do not distinguish the real from the non-existent ("What-is" and "What-is-Not"). In this poem Parmenides unfolds his philosophy: that all things are One, and therefore nothing can be changed or altered. Hence, all the things that we think to be true, even ourselves, are false representations.{{sfnm|1a1=Warren|1y=2014|1pp=77-80|2a1=Sandywell|2y=1996|2p=300}} What-is, according to Parmenides, is a physical sphere that is unborn, unchanged, and infinite.{{sfn|Warren|2014|pp=98}} This is a monist vision of the world, far more radical than that of Heraclitus.{{sfn|Warren|2014|p=80}} The goddess teaches Kouros to use his reasoning to understand whether various claims are true or false, discarding senses as fallacious.{{sfn|Curd|2020|loc= Parmenides of Elea}} Other fundamental issues raised by Parmenides' poem are the doctrine that [[Creatio ex materia|nothing comes from nothing]]{{sfn|Sandywell|1996|p=312}} and the unity of being and thinking. As quoted by DK fragment 3: ''To gar auto noein estin te kai einai'' (For to think and to be is one and the same).{{sfn|Sandywell|1996|p=298}}

Zeno and Melissus continued Parmenides' thought on cosmology.{{sfn|Warren|2014||pp=103-104}} Zeno is mostly known for his [[paradox]]es, i.e., self-contradictory statements which served as proofs that Parmenides' monism was valid, and that pluralism was invalid. The most common theme of those paradoxes involved traveling a distance, but since that distance comprises infinite points, the traveler could never accomplish it. His most famous is the Achilles paradox, which is mentioned by Aristotelis: "The second is called the 'Achilles' and says that the slowest runner will never be caught by the fastest, because it is necessary for the pursuer first to arrive at the point from which the pursued set off, so it is necessary that the slower will always be a little ahead." (Aristotle Phys. 239b14–18 [DK 29 A26]){{sfn|Warren|2014|p=108}} Melissus defended and advanced Parmenides' theory using prose, without invoking divinity or mythical figures. He tried to explain why humans think various non-existent objects exist.{{sfnm|1a1=Barnes|1y=1987|1pp=148-149|2a1=Warren|2y=2014|2pp=103-104}}

The Eleatics' focus on Being through means of logic initiated the philosophical discipline of ontology. Other philosophers influenced by the Eleatics (such as the Sophists, Plato, and Aristotle) further advanced logic, argumentation, mathematics and especially ''elenchos'' (proof). The Sophists even placed Being under the scrutiny of elenchos. Because of the Eleatics reasoning was acquiring a formal method.{{sfn|Sandywell|1996|pp=349-350}}

===The Pluralists: Anaxagoras and Empedocles<span class="anchor" id="Pluralists"></span>===
[[File:The Death of Empedocles by Salvator Rosa.jpg|thumb|alt=Salvator Rosa's painting ''The Death of Empedocles''|''The Death of Empedocles'' by [[Salvator Rosa]]. Legend holds that Empedocles committed suicide by falling into [[Mount Etna|Mount Etna's volcano]].{{sfn|Sandywell|1996|p=356}}]]
The Pluralist school marked a return to Milesian natural philosophy, though much more refined because of Eleatic criticism.<ref>{{harvnb|Warren|2014|p=3|ps=:Warren also adds Democritus as a pluralist.}}</ref>

[[Anaxagoras]] was born in Ionia, but was the first major philosopher to emigrate to Athens. He was soon associated with the Athenian statesman [[Pericles]] and, probably due to this association, was accused by a political opponent of Pericles for [[impiety]] as Anaxagoras held that the sun was not associated with divinity; it was merely a huge burning stone. Pericles helped Anaxagoras flee Athens and return to Ionia.{{sfn|Warren|2014|p=119}} Anaxagoras was also a major influence on [[Socrates]].{{sfn|Warren|2014|pp=132-133}}

Anaxagoras is known for his "theory of everything".{{sfn|Curd|2008|p=230}} He claimed that "in everything there is a share of everything." Interpretations differ as to what he meant. Anaxagoras was trying to stay true to the Eleatic principle of the everlasting (What-is) while also explaining the diversity of the natural world.{{sfn|Curd|2008|p=231}} Anaxagoras accepted Parmenides' doctrine that everything that exists (What-is) has existed forever, but contrary to the Eleatics, he added the ideas of ''[[panspermia]]'' and ''[[nous]]''. All objects were mixtures of various elements, such as air, water, and others. One special element was ''nous'', i.e., mind, which is present in living things and causes motion. 

According to Anaxagoras, ''Nous'' was one of the elements that make up the cosmos. Things that had ''nous'' were alive.  According to Anaxagoras, all things are composites of some basic elements; although it is not clear what these elements are.{{sfn|Warren|2014|pp=121-122}} All objects are a mixture of these building blocks and have a portion of each element,  except ''nous''. ''Nous'' was also considered a building block of the cosmos, but it exists only in living objects. Anaxagoras writes: "In everything there is a portion (''[[Moirai|moira]]'') of everything except mind (''nous''), but there are some things in which mind too is present."{{sfn|Warren|2014|p=125 DK 59 B11:6 }} ''Nous'' was not just an element of things, somehow it was the cause of setting the universe into motion.  Anaxagoras advanced Milesian thought on epistemology, striving to establish an explanation that could be valid for all natural phenomena. Influenced by the Eleatics, he also furthered the exploration of metatheoretical questions such as the nature of knowledge.{{sfn|Curd|2008|p=231}}

[[Empedocles]] was born in [[Agrigento|Akragas]], a town in the southern Italian peninsula. According to [[Diogenes Laertius]], Empedocles wrote two books in the form of poems: ''Peri Physeos'' (On nature) and the ''Katharmoi'' (Purifications). Some contemporary scholars argue these books might be one; all agree that interpreting Empedocles is difficult.{{sfnm|1a1=Primavesi|1y=2008|1pp=250|2a1=Warren|2y=2014|2pp=135-137}}

On cosmological issues, Empedocles takes from the Eleatic school the idea that the universe is unborn, has always been and always will be. He also continues Anaxagoras' thought on the four "roots" (i.e., classical elements), that by intermixing, they create all things around us. These roots are fire, air, earth, and water. Crucially, he adds two more components, the immaterial forces of love and strife. These two forces are opposite and by acting upon the material of the four roots unite in harmony or tear apart the four roots, with the resulting mixture being all things that exist. Empedocles uses an analogy of how this is possible: as a painter uses a few basic colors to create a painting, the same happens with the four roots. It is not quite clear if love and strife co-operate or have a greater plan, but love and strife are in a continual cycle that generates life.{{sfnm|1a1=Warren|1y=2014|1pp=137-141|2a1=Vamvacas|2y=2009|2pp=169-172}} Other beings, apart from the four roots and love and strife, according to Empedocles' ''Purifications'' are mortals, gods, and [[Daemon (classical mythology)|daemons]].{{sfn|Warren|2014|p=146}} Like Pythagoras, Empedocles believed in the soul's transmigration and was vegetarian.{{sfn|Primavesi|2008|p=251}}

===Atomists: Leucippus and Democritus ===
{{Main|Atomism}}
[[File:Hendrik ter Brugghen - Democritus.jpg|thumb|alt= Painting ''Democritus'' by [Hendrick ter Brugghen |''Democritus'' by [[Hendrick ter Brugghen]], 1628. Democritus was known as the "laughing philosopher"{{sfn|Sandywell|1996|p=380}}]]

Leucippus and Democritus both lived in [[Abdera, Thrace|Abdera]], in [[Thrace]]. They are most famous for their atomic cosmology even though their thought included many other fields of philosophy, such as ethics, mathematics, aesthetics, politics, and even embryology.{{sfn|Warren|2014|pp=153-154}}

The atomic theory of Leucippus and Democritus was a response to the Eleatic school, who held that motion is not possible because everything is occupied with What-is. Democritus and Leucippus reverted the Eleatic axiom, claiming that since motions exist, What-is-not must also exist; hence void exists. Democritus and Leucippus were skeptics regarding the reliability of our senses, but they were confident that motion exists.{{sfn|Warren|2014|pp=155-157}} Atoms, according to Democritus and Leucippus, had some characteristics of the Eleatic What-is: they were homogeneous and indivisible. These characteristics allowed answers to [[Zeno's paradoxes]].{{sfn|Warren|2014|pp=157-161}} Atoms move within the void, interact with each other, and form the plurality of the world we live in, in a purely mechanical manner.{{sfn|Warren|2014|p=163}}

One conclusion of the Atomists was [[determinism]] - the philosophical view that all events are determined completely by previously existing causes. As Leucippus said, (DK 67 B2) "Nothing comes to be random but everything is by reason and out of necessity."{{sfn|Warren|2014|pp=164-165}} Democritus concluded that since everything is atoms and void, several of our senses are not real but conventional. Color, for example, is not a property of atoms; hence our perception of color is a convention. As Democritus said, (DK 68 B9) "By convention sweet, by convention bitter, by convention hot, by convention cold, by convention colour; in reality atoms and void."{{sfn|Warren|2014|pp=166-167}} This can be interpreted in two ways. According to James Warren there is an [[Eliminative materialism|eliminativist]] interpretation, such that Democritus means that color is not real, and there is a [[relativism|relativist]] interpretation, such that Democritus means that color and taste are not real but are perceived as such by our senses through sensory interaction.{{sfn|Warren|2014|p=169}}

===Sophists===
{{Main|Sophism}}

The sophists were a philosophical and [[History of education#Greece and Rome|educational]] movement that flourished in ancient Greece before Socrates. 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.{{sfn|Gagarin|Woodruff|2008|p=367}}

Plato disparaged the sophists, causing long-lasting harm to their reputation. Plato thought philosophy should be reserved for those who had the appropriate intellect to understand it; whereas the sophists would teach anyone who would pay tuition.{{sfn|Gagarin|Woodruff|2008|pp=365-367}} The sophists taught rhetoric and how to address issues from multiple viewpoints. Since the sophists and their pupils were persuasive speakers at court or in public, they were accused of moral and epistemological relativism,{{sfn|Graham|2021|loc= The Sophists and Anonymous Sophistic Texts}} which indeed some sophists appeared to advocate. Prominent sophists include [[Protagoras]], [[Gorgias]], [[Hippias]], [[Thrasymachus]], [[Prodicus]], [[Callicles]], [[Antiphon (orator)|Antiphon]], and [[Critias]].{{sfn|Gagarin|Woodruff|2008|pp=366-368}}

Protagoras is mostly known for two of his quotes. One is that  "[humans are..] ''the measure of all things, of things that are that they are, of things that are not that they are not"'' which is commonly interpreted as affirming philosophical [[relativism]], but it can also be interpreted as claiming that knowledge is only relevant to humankind, that moral rightness and other forms of knowledge are relevant to and limited to human mind and perception. The other quote is, "Concerning the gods, I cannot ascertain whether they exist or whether they do not, or what form they have; for there are many obstacles to knowing, including the obscurity of the question and the brevity of human life."{{sfn|Graham|2021|loc=Protagoras}}

Gorgias wrote a book named ''On Nature,'' in which he attacked the Eleatics' concepts of What-is and What-is-not. He claimed it is absurd to hold that nonexistence exists, and that What-is was impossible since it had to either be generated or be unlimited and neither is sufficient. There is an ongoing debate among modern scholars whether he was a serious thinker, a precursor of extreme relativism and skepticism, or merely a charlatan.{{sfn|Graham|2021|loc=Gorgias}}

Antiphon placed natural law against the law of the city. One need not obey the city's laws as long as one will not get caught. One could argue that Antiphon was a careful hedonist—rejecting dangerous pleasures.{{sfn|Graham|2021|loc=Antiphon}}

=== Philolaous of Croton and Diogenes of Apollonia ===
[[Philolaus|Philolaus of Croton]] and [[Diogenes of Apollonia]] from [[Thrace]] (born {{circa}} 460 BC) are considered the last generation of pre-Socratics. Rather than advancing a cosmological perspective on how our universe is constructed, they are mostly noted for advancing abstract thinking and argumentation.{{sfn|Warren|2014|p=179}}<br/>
Pythagorianism, Anaxagoras and Empedocles influenced Philolaus. He attempted to explain both the variety and unity of the cosmos. He addressed the need to explain how the various masses of the universe interact among them and coined the term ''Harmonia'', a binding force that allows mass to take shape. The structure of the cosmos consisted of ''apeira'' (unlimiteds) and ''perainonta'' (limiters).{{sfn|Warren|2014|pp=175-177}}
Diogenes of Apollonia returned to Milesian monism, but with a rather more elegant thought. As he says in DK64 B2 "It seems to me, overall, that all things are alterations of the same things and are the same thing". He explains that things, even when changing shapes, remain ontologically the same.{{sfn|Warren|2014|pp=178-179}}