Ontology, the philosophical study of being in
general, or of what applies neutrally to everything that is real. It was called
“first philosophy” by Aristotle in Book IV of his Metaphysics. The Latin term
ontologia (“science of being”) was felicitously invented by the German
philosopher Jacob Lorhard (Lorhardus) and first appeared in his work Ogdoas
Scholastica (1st ed.) in 1606. It entered general circulation after being
popularized by the German rationalist philosopher Christian Wolff in his Latin
writings, especially Philosophia Prima sive Ontologia (1730; “First Philosophy
or Ontology”).
History and scope
Wolff contrasted ontology, or general
metaphysics, which applied to all things, with special metaphysical theories
such as those of the soul, of bodies, or of God. Wolff claimed that ontology
was an a priori discipline that could reveal the essences of things, a view
strongly criticized later in the 18th century by David Hume and Immanuel Kant.
In the early 20th century the term was adopted by the German founder of
phenomenology, Edmund Husserl, who called Wolff’s general metaphysics “formal
ontology” and contrasted it with special “regional ontologies,” such as the
ontologies of nature, mathematics, mind, culture, and religion. After renewed
criticism and eclipse under the antimetaphysical movement known as logical
positivism, ontology was revived in the mid-20th century by the American
philosopher W.V.O. Quine. By the end of the century, largely as the result of
Quine’s work, it had regained its status as a central discipline of philosophy.
The history of ontology has consisted largely
of a set of fundamental, often long-running and implacable disputes about what
there is, accompanied by reflections about the discipline’s own methods,
status, and fundamental concepts—e.g., being, existence, identity, essence,
possibility, part, one, object, property, relation, fact, and world. In a
typical ontological dispute, one group of philosophers affirms the existence of
some category of object (realists), while another group denies that there are
such things (antirealists). Such categories have included abstract or ideal
Forms, universals, immaterial minds, a mind-independent world, possible but not
actual objects, essences, free will, and God. Much of the history of philosophy
is in fact a history of ontological disputes.
Once they have been brought into the open,
ontological disputes tend to concentrate on questions of several recurrent
kinds. The fundamental question, of course, has the form, “Are there Xs?” or
“Do Xs exist?” Negative answers to the fundamental question are accompanied by
attempts to explain away any appearances to the effect that there are such
things. If the question is answered affirmatively, there are subsequent
questions. Do Xs exist independently of minds and languages (objectively), or
do they depend on them in some way (subjectively or intersubjectively)? Are
they discovered or created? Are they basic, irreducible constituents of
reality, or can they be reduced to others? For example, in the millennia-long
dispute about universals, realists have affirmed mind-independent universals,
whether existing apart or only in things; conceptualists have taken universals
to be mental or mind-created entities; moderate nominalists such as Thomas
Hobbes (1588–1679) have taken them to be words or linguistic entities; and
extreme nominalists have denied that there are any universals at all. Among
modern Platonists, some take universals to be basic or sui generis, while
others take them to be reducible to sets.
In general, a philosopher who believes in many
fundamentally different kinds of object has a rich ontology, and one who
believes in only a few kinds of object has a sparse ontology. Rich ontologists
include Plato, who recognized immaterial Forms as well as material bodies, and
the Austrian philosopher Alexius Meinong (1853–1920), who embraced merely
possible and even impossible objects alongside actual objects. Sparse
ontologists include William of Ockham (c. 1285–1347), who accepted only
qualities, or properties, and the substances in which they inhere, as well as a
few relations; and Quine, who accepted only things (material bodies) and
mathematical sets, professing an ontological taste for “desert landscapes.”
Methods
The methods of ontology vary according to the
extent to which the ontologist wishes to rely upon other disciplines and the
nature of the disciplines he wishes to rely upon. The most common method since
the 20th century, the logical or linguistic method, relied upon theories of
meaning or reference—as applied to either artificial logical languages or to
natural languages—to dictate the kinds of entity that exist. Typically, lists
of basic categories reflecting this method tended to correspond closely to
broad linguistic (or syntactic) categories—e.g., substance (noun), property
(adjective), relation (transitive verb), and state of affairs (sentence). A
shortcoming of the logico-linguistic method, however, is that it is generally
possible to change the ontology it produces by varying the semantic analysis of
the natural or formal language in question.
Other ontological methods have been based on
phenomenology (Husserl, Meinong), on the analysis of human existence, or Dasein
(Martin Heidegger), and on epistemology. Husserl and Meinong contended that the
basic categories of objects mirror the various kinds of mental activity by
which they are grasped. Thus, there must be four basic kinds of objects
corresponding to the mental activities of ideation, judgment, feeling, and
desire. Heidegger held that it is a mistake to base the ontology of human
existence on Aristotelian concepts such as matter and form, which are suitable
only for artifacts.
The most widely used linguistic criterion of
existence is due to Quine, who coined the slogan “To be is to be the value of a
variable.” According to Quine, the propositions of a scientific theory should
first be expressed in terms of predicate logic, or the predicate calculus, a
logical language consisting of names, variables (which may be substituted for
names), predicates (or properties), logical connectives (such as and, or, and
if…then), and quantifiers. (Quantifiers can be combined with predicates and
variables to form sentences equivalent to “Everything has such and such a
property” and “There is at least one thing that has such and such a property.”)
The scientific theory is then ontologically “committed” to those classes of
entity whose members must be capable of replacing variables (i.e., capable of
being the value of a variable) if the sentences of the theory are to be true.
Quine rejected any primacy for ontology,
claiming that ontological categories should be suggested by natural science.
Yet this did not prevent him from sometimes intervening on an apparently ad hoc
basis to reduce the ontological commitments of classes of scientific theories
to those of his minimal ontology of things and sets. His streamlining of
scientific ontology to the minimum needed to keep the structure of scientific
discourse intact led him to the doctrine of “ontological relativity,” according
to which there is no privileged category of objects to which a given scientific
theory is ontologically committed.
In contrast to Quine, philosophers such as
Alfred North Whitehead (1861–1947) in England and David Armstrong in Australia
regarded ontology as a core philosophical discipline that cannot depend to such
a decisive extent on any other philosophical or scientific study. Its results
can be evaluated only in terms of the adequacy of the overall system in the
light of experience.
Peter+M. Simons
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