Philosophy is the study of general and fundamental questions about existence, knowledge, values, reason, mind, and language.  Such questions are often posed as problems to be studied or resolved. The term was probably coined by Pythagoras. Philosophical methods include questioning, critical discussion, rational argument, and systematic presentation.

Classic philosophical questions include: "Is it possible to know anything?", and if so, "Can we prove it?" Philosophers also pose more practical and concrete questions such as: "Is there a best way to live?", "Is it better to be just, even if one could get away with being unjust?", 'do humans have free will?'

Initially, the term 'philosophy' referred to any body of knowledge. In this sense, philosophy is closely related to religion, mathematics, natural science, education, and politics. Though as of the 2000s it has been classified as a book of physics, Newton's Mathematical Principles of Natural Philosophy (1687) uses the term natural philosophy as it was understood at the time to encompass disciplines, such as astronomy, medicine and physics, that later became associated with sciences.