section_path: Schools of thought/Others
section_name: Others
paragraph_text: Others
  
  The dispute between constituent and relational ontologies concerns the internal structure of concrete particular objects. Constituent ontologies say that objects have an internal structure with properties as their component parts. Bundle theories are an example of this position: they state that objects are bundles of properties. This view is rejected by relational ontologies, which say that objects have no internal structure, meaning that properties do not inhere in them but are externally related to them. According to one analogy, objects are like pin-cushions and properties are pins that can be stuck to objects and removed again without becoming a real part of objects. Relational ontologies are common in certain forms of nominalism that reject the existence of universal properties.
  
  Hierarchical ontologies state that the world is organized into levels. Entities on all levels are real but low-level entities are more fundamental than high-level entities. This means that they can exist without high-level entities while high-level entities cannot exist without low-level entities. One hierarchical ontology says that elementary particles are more fundamental than the macroscopic objects they compose, like chairs and tables. Other hierarchical theories assert that substances are more fundamental than their properties and that nature is more fundamental than culture. Flat ontologies, by contrast, deny that any entity has a privileged status, meaning that all entities exist on the same level. For them, the main question is only whether something exists rather than identifying the level at which it exists.
  
  The ontological theories of endurantism and perdurantism aim to explain how material objects persist through time. Endurantism is the view that material objects are three-dimensional entities that travel through time while being fully present in each moment. They remain the same even when they gain or lose properties as they change. Perdurantism is the view that material objects are four-dimensional entities that extend not just through space but also through time. This means that they are composed of temporal parts and, at any moment, only one part of them is present but not the others. According to perdurantists, change means that an earlier part exhibits different qualities than a later part. When a tree loses its leaves, for instance, there is an earlier temporal part with leaves and a later temporal part without leaves.
  
  Differential ontology is a poststructuralist approach interested in the relation between the concepts of identity and difference. It says that traditional ontology sees identity as the more basic term by first characterizing things in terms of their essential features and then elaborating differences based on this conception. Differential ontologists, by contrast, privilege difference and say that the identity of a thing is a secondary determination that depends on how this thing differs from other things.
  
  Object-oriented ontology belongs to the school of speculative realism and examines the nature and role of objects. It sees objects as the fundamental building blocks of reality. As a flat ontology, it denies that some entities have a more fundamental form of existence than others. It uses this idea to argue that objects exist independently of human thought and perception.