Philosophy is the study of general problems concerning matters such as existence, knowledge, truth, beauty, justice, validity, mind, and language.[1][2] Philosophy is distinguished from other ways of addressing these questions (such as mysticism or mythology) by its critical, generally systematic approach and its reliance on reasoned argument.[3] The word philosophy is of Ancient Greek origin: φιλοσοφία (philosophía), meaning "love of wisdom."[4][5][6]
To give an exhaustive list of the main branches of philosophy is difficult, because there have been different, equally acceptable divisions at different times, and the divisions are often relative to the concerns of a particular period. However, the following branches are usually accepted as the main areas of study.
Most academic subjects have a philosophy, for example the philosophy of science, the philosophy of mathematics, the philosophy of logic and the philosophy of history. In addition, a range of academic subjects has emerged to deal with areas which would have historically been the subject of philosophy. These include psychology, anthropology and science.
The introduction of the terms "philosopher" and "philosophy" has been ascribed to the Greek thinker Pythagoras (see Diogenes Laertius: "De vita et moribus philosophorum", I, 12; Cicero: "Tusculanae disputationes", V, 8-9). The ascription is based on a passage in a lost work of Herakleides Pontikos, a disciple of Aristotle. It is considered to be part of the widespread legends of Pythagoras of this time. "Philosopher" replaced the word "sophist" (from sophoi), which was used to describe "wise men," teachers of rhetoric, who were important in Athenian democracy.
The history of philosophy is customarily divided into six periods: Ancient philosophy, Medieval philosophy, Renaissance philosophy, Early and Late Modern philosophy and Contemporary philosophy.
Ancient philosophy is the philosophy of the Graeco-Roman world from the sixth century [circa 585] B.C. to the fourth century A.D. It is usually divided into four periods: the pre-Socratic period, the periods of Plato and Aristotle, and the post-Aristotelian (or Hellenistic) period. Sometimes a fifth period is added that includes the Christian and Neo-Platonist philosophers. The most important of the ancient philosophers (in terms of subsequent influence) are Plato and Aristotle[7].
The themes of ancient philosophy are: understanding the fundamental causes and principles of the universe; explaining it in an economical and uniform way; the epistemological problem of reconciling the diversity and change of the natural universe, with the possibility of obtaining fixed and certain knowledge about it; questions about things which cannot be perceived by the senses, such as numbers, elements, universals, and gods; the analysis of patterns of reasoning and argument; the nature of the good life and the importance of understanding and knowledge in order to pursue it; the explication of the concept of justice, and its relation to various political systems[8].
In this period the crucial features of the philosophical method were established: a critical approach to received or established views, and the appeal to reason and argumentation.
Medieval philosophy is the philosophy of Western Europe and the Middle East during what is now known as the medieval era or the Middle Ages, roughly extending from the fall of the Roman Empire to the Renaissance. Medieval philosophy is defined partly by the rediscovery and further development of classical Greek and Hellenistic philosophy, and partly by the need to address theological problems and to integrate sacred doctrine (in Islam, Judaism and Christianity) with secular learning.
Some problems discussed throughout this period are the relation of faith to reason, the existence and unity of God, the object of theology and metaphysics, the problems of knowledge, of universals, and of individuation.
Philosophers from the Middle Ages include the Muslim philosophers Alkindus, Alfarabi, Alhazen, Avicenna, Algazel, Avempace, Abubacer and Averroes; the Jewish philosophers Maimonides and Gersonides; and the Christian philosophers Anselm, Peter Abelard, Roger Bacon, Thomas Aquinas, Duns Scotus, William of Ockham and Jean Buridan.