Philosophy is a systematic study of fundamental questions concerning topics like existence, reason, knowledge, value, and mind. It is a rational and critical inquiry that reflects on its own methods and assumptions. Major branches of philosophy are epistemology, ethics, logic, and metaphysics. Epistemology studies what knowledge is and how to acquire it. Ethics investigates the principles of moral conduct. Logic is the study of correct reasoning. Metaphysics examines the most general features of reality. Philosophical methods include analysis of concepts and language, reliance on common sense and intuitions, use of thought experiments, description of experience, and critical questioning. Influential traditions are Western, Arabic–Persian, Indian, and Chinese philosophy. Many of the sciences were part of philosophy before they became separate disciplines. Philosophy is relevant to diverse fields of inquiry by studying their scope and concepts and providing an interdisciplinary perspective. (Full article...)