section_path: Abstract
section_name: Abstract
paragraph_text: Metaphysics is the branch of philosophy that examines the basic structure of reality. It is often characterized as first philosophy, implying that it is more fundamental than other forms of philosophical inquiry. Metaphysics is traditionally seen as the study of mind-independent features of the world, but some modern theorists understand it as an inquiry into the conceptual schemes that underlie human thought and experience.
  
  Many general and abstract topics belong to the subject of metaphysics. It investigates the nature of existence, the features all entities have in common, and their division into categories of being. An influential contrast is between particulars, which are individual unique entities, like a specific apple, and universals, which are general repeatable entities that characterize particulars, like the color red. Modal metaphysics examines what it means for something to be possible or necessary. The nature of space, time, and change is also discussed by metaphysicians. A closely related issue concerns the essence of causality and its relation to the laws of nature. Other topics include how mind and matter are related, whether everything in the world is predetermined, and whether there is free will.
  
  Metaphysicians employ various methods to conduct their inquiry. Traditionally, they rely on rational intuitions and abstract reasoning but have more recently also included empirical approaches associated with scientific theories. Due to the abstract nature of its topic, metaphysics has received criticisms questioning the reliability of its methods and the meaningfulness of its theories. Metaphysics is relevant to many fields of inquiry that often implicitly rely on metaphysical concepts and assumptions.
  
  The origin of metaphysics lies in antiquity with speculations about the nature of reality and the universe, like those found in the Upanishads in ancient India, Daoism in ancient China, and pre-Socratic philosophy in ancient Greece. The subsequent medieval period in the West discussed the nature of universals as shaped by ancient Greek philosophers Plato and Aristotle. The modern period saw the emergence of various comprehensive systems of metaphysics, many of which embraced idealism. In the 20th century and contemporary period, a "revolt against idealism" was started, and metaphysics was once declared meaningless, then revived with various criticisms of earlier theories and new approaches to metaphysical inquiry.