What was the major difference between ancient Greek and Medieval philosophy?
Greek philosophy started in the 6th century BCE. Greek philosophy is one of the primary influencing forms of philosophy on the entirety of Western Civilization. It can be divided into Pre-Socratic philosophy, Classical Greek philosophy and Hellenistic philosophy.
Pre-Socratic philosophy focused on math, the cosmos and ontology, rejecting myth in favor of reason and discussion. Key pre-socratic philosophers included Thales of Mieltus, Anaximander, Xenophanes, Pythagoras, Heraclitus and Parmenides of Eleas, Protagoras, Prodicus, Gorgias, Hippies, and Thrasymachus.
Most people are more familiar with Classical Greek philosophy. These philosophers include the famous Socrates (470/469-399 BC), Plato and Aristotle. Socrates is famed with developing the socratic method and much of what is known from him is from his student Plato and his writings on their dialogue. Plato (428/427 or 424/423 - 348/347 BC) founded the Academy in Athens, the first place of higher learning in Western Civilization. Plato was the creator of dialogue and dialectic methods in philosophy. Aristotle (384-322 BC) was a Greek philosopher whose theories and ethics studied under Plato and his influence are still felt throughout Western thought.
Medieval philosophy departs from Greek philosophy as it is primarily focused and defined by focus on monotheistic ideologies. At this time Christianity, Islamic and Jewish thought come to the forefront. Medieval philosophy began at the fall of Rome in the 5th century C.E. to the Renaissance in the 16th century. It can be divided into two sections, the Latin West right after the Early Middle Ages until the 12th century and then post the 12th century during the ‘Golden Age’ during which Aristotle and Plato’s texts were rediscovered. Medieval philosophy is primarily theological; one of the key thinkers of this time period was Thomas Aquinas. Generally all the philosophers of this time focused on logic, dialectic and reasoning to discover the truth.
So what it boils down to is the inclusion of monotheistic religion in Medieval philosophy and the loss of access to written texts during this time, but then again renewed towards the second period of medieval philosophy when scholastic research was renewed and the influence of Plato and Aristotle began to become more important.
The single greatest change between what is termed ancient and what is termed medieval philosophy was the rise of Christianity and the concomitant necessity to synthesize Scriptural interpretation with more abstract philosophical theorizing. However, it would be inaccurate to think of this change as a dramatic rupture. The scripturalizing phenomenon was not unique to Christianity. Among Stoics, for example, there was a major debate concerning whether it was more important to produce exegesis of Chrysippus or to work from basic principles. Similarly, most of the Neoplatonic texts after Plotinus occur in the forms of commentary on Platonic dialogues, and in method are not radically different from many of the commentaries of Augustine or Origen on the Bible. Furthermore, many Christian theologians were strongly influenced by ancient philosophy.
Ancient Greek philosophy spanned the time period from the Pre-Socratic philosophers (around 6th Century BCE) in Ancient Greece all the way up through the Roman Empire. The transition from ancient to medieval times or the middle ages is commonly marked with the fall of the Western Roman Empire, around the 5th Century C.E. Although a big part of the rise of medieval philosophy was an attempt to revisit the questions of ancient Greek philosophy, philosophy had now changed in one big way: theology.
The main departure from ancient Greek philosophy into medieval philosophy is that philosophers are now trying to incorporate religious doctrine and theological concerns into their philosophical quandaries. Many of the religious ideas were rooted in Christianity. Proofs of the existence of God, such as St. Thomas Aquinas' Cosmological Argument and St. Anselm's Ontological Argument, were common during this time period. Questions of faith versus reason and the attributes of the divine were also common, although they were previously almost non-existent in ancient Greece. However, medieval philosophy also drew heavily on Aristotelian thought regarding metaphysics, logic, and philosophy of mind.