section_path: Topics/Universals
section_name: Universals
paragraph_text: Universals
  
  Universals are general entities, encompassing both properties and relations, that express what particulars are like and how they resemble one another. They are repeatable, meaning that they are not limited to a unique existent but can be instantiated by different particulars at the same time. For example, the particulars Nelson Mandela and Mahatma Gandhi instantiate the universal humanity, similar to how a strawberry and a ruby instantiate the universal red.
  
  A topic discussed since ancient philosophy, the problem of universals consists in the challenge of characterizing the ontological status of universals. Realists argue that universals are real, mind-independent entities that exist in addition to particulars. According to Platonic realists, universals exist also independently of particulars, which implies that the universal red would continue to exist even if there were no red things. A more moderate form of realism, inspired by Aristotle, states that universals depend on particulars, meaning that they are only real if they are instantiated. Nominalists reject the idea that universals exist in either form. For them, the world is composed exclusively of particulars. The position of conceptualists constitutes a middle ground: they state that universals exist, but only as concepts in the mind used to order experience by classifying entities.
  
  Natural and social kinds are often understood as special types of universals. Entities belonging to the same natural kind share certain fundamental features characteristic of the structure of the natural world. In this regard, natural kinds are not an artificially made-up classification but are discovered, usually by the natural sciences, and include kinds like electrons, H O, and tigers. Scientific realists and anti-realists are in disagreement about whether natural kinds exist. Social kinds are studied by social metaphysics and characterized as useful social constructions that, while not purely fictional, fail to reflect the fundamental structure of mind-independent reality. Uncontroversial examples include money or baseball.