Scholars adopt three main approaches to the history of philosophy. The presentist approach to the history of philosophy examines philosophical texts for the arguments they contain and judges whether their conclusions remain relevant for philosophical concerns today. While making the wisdom of the past available for present applications, this approach has been critiqued on two points: 1) in reading philosophical texts too narrowly, past philosophers are judged by contemporary standards; 2) this approach may also result in anachronistic errors, as ideas from contemporary philosophy may be inaccurately attributed to historical philosophers. A contextualist approach interprets philosophy in terms of the historical and cultural contexts in which it was written. While this approach can yield deep understanding of historical moments and historical ways of thinking, it can be blind to the lasting value of philosophical inquiry. A hermeneutic approach attempts to take the best of the presentist and contextualists approaches, viewing the historical context of original texts seriously but also recognizing that our interpretation of history is connected to and conditioned by our contemporary context.
Classical Greek philosophy owes much to Egyptian scholarship emanating from Heliopolis, as both Pythagoras and Plato are believed to have studied at that center of learning. Indeed, the Plimpton 332 clay tablet reveals that Babylonian mathematicians knew not only of the Pythagorean theorem of right triangles but also of trigonometric functions. Classical philosophy emerged in ancient Greece with the Presocratics; the three great philosophers Socrates (470–399 BCE), Plato (c. 428–347 BCE), and Aristotle (384–322 BCE); and schools of thought that came after—Epicureans, stoics, and others. From what remains of the works of the Presocratics, they were primarily interested in questions of metaphysics and natural philosophy. Some Presocratics, such as Parmenides, were monists while others, such as Heraclitus, were plurists. Plato advanced a theory of the forms, a metaphysical doctrine that holds that every particular thing that exists participates in an immaterial form or essence that gives this thing its identity. The invisible realm of the forms differs fundamentally from the changing realm we experience in this world. The invisible realm is eternal, unchanging, and perfect. Aristotle’s work centers on his doctrine of the four causes: “What’s it made of?” (material cause), “What shape does it have?” (formal cause), “What agent gave it this form?” (efficient cause), and, finally, “What is its end goal?” (final cause). The four causes can explain nature of all things in this universe, including the universe itself. Aristotle’s universe is a closed system of final causes. Each final cause leads to another, until we get to the first cause or prime mover.
Greek and Roman imperialism in the Middle East and North Africa brought Jews—and later, Christians—into the intellectual sphere of Hellenism. Jewish and later Christian scholars incorporated ideas of classical Greek and Roman philosophy into their own theological studies. As Arab conquerors and traders expanded into the Middle East and Africa, the Muslim world adopted and advanced classical philosophy and the natural sciences. Yet a tension at all times runs through these works as philosophers tried to balance theological revelation and freedom of intellectual exploration. Unlike the classical Greek and Roman philosophers, the Jewish, Christian, or Muslim philosopher always works with a partner, the events and facts central to the religion. It is only in the early modern age that philosophers replace the primacy of God as the source of truth with reason.