Abstract object
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- For other uses, see Abstract
In philosophy it is commonly considered that every object is either abstract or concrete. Abstract objects are sometimes called abstracta (sing. abstractum) and concrete objects are sometimes called concreta (sing. concretum). The abstract-concrete distinction is often introduced and initially understood in terms of paradigmatic examples of objects of each kind:
| Abstracta | Concreta |
| Tennis | Tennis player |
| Redness | A particular inscription of the word "red" |
| 5 (number) | Five cats |
| Justice | Court |
| humanism | human |
Contents |
[edit] Definition
Philosophers disagree over just what makes the items in the first column abstract.
[edit] Location
One well-known proposal is that an object is abstract if and only if it lacks a location in space. Thus justice is abstract because it has no spatial location. One potential problem for this proposal is that certain typically abstract objects, like the game of tennis, arguably do have a sort of spatial location (e.g. "Tennis is alive and well in New York City"). Another problem is that some arguably concrete mental objects (e.g. Tim’s pang of concern for his eldest daughter) do not have spatial location.
[edit] Causal power
Another popular proposal for drawing the abstract-concrete distinction has it that an object is abstract if it lacks any causal powers. A causal power is an ability to affect something causally. Thus the empty set is abstract because it cannot act on other objects. One problem for this view is that it is not clear exactly what it is to have a causal power. For a more detailed exploration of the abstract-concrete distinction, follow the link below to the Stanford Encyclopedia article.
[edit] In philosophy
Abstract objects have often garnered the interest of philosophers because they are taken to raise problems for popular theories. In ontology, abstract objects are considered problematic for physicalism and naturalism. Historically, the most important ontological dispute about abstract objects has been the problem of universals. In epistemology, abstract objects are considered problematic for empiricism. If abstracta lack causal powers or spatial location, how do we know about them? It is hard to say how they can affect our sensory experiences, and yet we seem to agree on a wide range of claims about them. Some, such as Edward Zalta and arguably Plato (in his Theory of Forms), have held that abstract objects constitute the defining subject matter of metaphysics or philosophical inquiry more broadly. To the extent that philosophy is independent of empirical research, and to the extent that empirical questions do not inform questions about abstracta, philosophy would seem specially suited to answering these latter questions.
[edit] Terminology
- Further information: Noun#Concrete nouns and abstract nouns
In language, abstract and concrete objects are often synonymous with concrete nouns and abstract nouns. In English, many abstract nouns are formed by adding noun-forming suffixes ("-ness", "-ity", "-tion") to adjectives or verbs. Examples are "happiness", "circulation" and "serenity".
[edit] See also
- Abstraction
- Abstract structure
- Nominalism
- Object (philosophy)
- Philosophy of mathematics
- Platonic form
- Problem of universals
- Universal (metaphysics)
- Immanuel Kant
- Type-token distinction
[edit] External links
- Abstract Objects entry at the Stanford Encyclopedia of Philosophy by Gideon Rosen
- Nominalism, Realism, Conceptualism, from The Catholic Encyclopedia

