The term ontology (from Greek to on, ontos— being, entity; logos—concept, science) usually denotes: (a) a philosophical discipline that studies being (entity) as being (entity), that is, being in general; (b) the ontology of a theory: the kind of entities that should exist if the given theory is true. One of the fundamental problems of ontology (particularly in its first meaning) is the question about the relation between being and becoming and thus the question about the place and role of time in the explanation of reality.
As a philosophical discipline, ontology has existed at least since the time of Aristotle (384322 BCE), who in his Metaphysics claims that one of its tasks is to investigate “being as being and the attributes that belong to this in virtue of its own nature.” While the investigation itself is old, the name is relatively new. It was not created until the 17th century as a result of the efforts of ontology to emancipate itself as an element of metaphysics in relation to its other disciplines, most of all however in relation to (rational) theology. The first to have used it was the German scholastic Rudolf Goclenius (1547-1628) in his work Lexicon Philosophicum dated 1613, but it was Christian Wolff (1679-1754) who definitively introduced it into philosophical terminology and thus the period’s intellectual awareness. In his work Philosophia Prima Sive Ontologia from 1730, he identified ontology as a fundamental philosophical discipline within general metaphysics. While the latter describes being (entity) in general, the disciplines of specific metaphysics are concerned with its partial domains, such as God, soul (humanity), and nature.
Historically, there are three basic and interconnected areas of problems that differentiate themselves within ontology, and these may be briefly delimited by these three questions: (1) What is being? (2) What really exists? (3) What exists?
What Is Being, or, What
Does It Mean to Be, to Exist?
Although it may seem that this question would be central to ontology, most philosophers gave up on any serious research in this direction as something problematic, perhaps even impossible. Already Aristotle, in his polemics with Parmenides (540-450 BCE), considered it disputable to think of being as such—that is, as the most general concept in a single meaning, and he emphasized its polysemic nature. Blaise Pascal (1623-1662), for example, pointed out the danger of circular definition (circulus in definiendo) in such generally understood being (as it can only be determined with the help of the word “is”). Immanuel Kant (1724-1804) argued that being, or existence, is not an attribute (predicate). There is no empirical attribute within the concept of an existing object by which it would differ from the concept of a similar, but nonexisting, object. With similar intentions, modern logic solves the problem of statements about existence; for example, it transforms the statement Man is into a formally correct form of the statement with an existential quantifier, that is, There exists a thing that is a man.
Despite difficulties in thinking about being (existence), Martin Heidegger (1889-1976) attempted early in the 20th century to build a fundamental ontology, the main aim of which is exactly to seek the meaning of being. As opposed to the previous philosophy (ontotheology), which forgot about being, replaced it with entity, and would explain one entity with the help of another (even divine) entity, it is necessary to clearly distinguish an entity from the being of this entity (ontological difference). The key to the understanding of the meaning of being is the analytics of a particular type of entity—human being, being-there (dasein), through the medium of objectless forms of thinking—existentials. The project of fundamental ontology remained unfinished, but it inspired phenomenological, existentialist, and hermeneutical thinking in the given field (Jean- Paul Sartre, 1905-1980; Maurice Merleau- Ponty, 1980-1961; and others).
What Really Exists, or,
Which Things Do Really Exist?
Although the question “What does really, therefore truly, ultimately, exist?” is logically a version of the question “What exists?” it is historically older and it has been perhaps the most typical of ontological questions in traditional metaphysics since its beginnings. It presumes a split of reality into two ontologically as well as axiologically unequal fields: (a) a privileged, true reality (noumenon, substance) which exists in-itself, as a autonomous, changeless, and independent of all else, and (b) a secondary, ontologically less valuable phenomenon (fai- nomenon, akcidencia), which, as nonautono- mous and changeable, is derived from the first. It is mainly the ontology of middle-period Plato (428-348 BCE) that is paradigmatically known in this sense, with his differentiation of a perfect world of intelligible ideas and an imperfect world of empirical particulars, which have reality only to that extent to which they have a part in the former.
It is the same with time as a movable and imperfect picture of eternity. In his understanding of the first philosophy as a teaching about a divine substance, Aristotle supported such a model of an axiologically saturated ontology when he placed against each other the perfect entity of an unmoved first mover and the hierarchically lower, by their form dependent, and derived entities. Unlike the first one, their characteristic is time as a number of movement with regard to before and after.
The dispute between idealism and materialism also became classic in this sense. Idealism considered matter as merely a manifestation (other- being) of an absolute spirit, and time as intuitive becoming was the essential but imperfect and temporary manifestation of this spirit (G. W. F. Hegel 1770-1830), or a bundle of perceptions (ideas) of the human mind (G. Berkeley, 16851753). Materialism considered consciousness, mind, and spirit as merely a product, an attribute or a function of matter. This traditional, substantialist ontology model dominated until the times of Rene Descartes (1596-1650), or Kant, after which it became the subject of perennial criticism. In the 20th century, this criticism came mainly from analytical philosophy, but also from Heidegger, Alfred North Whitehead’s (1861-1947) process philosophy, Nicolai Hartmann’s (1882-1950) critical ontology, and others.
What Exists, or, Which
Kinds of Things Do Exist?
At the beginning of this investigation, more neutral and unreductionist—compared with the previous one—was Aristotle, with his understanding of ontology as teaching about categories, that is, about the most general kinds (predicates) of things. Categorical analysis has been a component of philosophy until the present day, but historically, both the understanding of the nature of categories and their selection have changed within it. While Aristotle understands them first and foremost realistically (they are the attributes of things themselves), and he lists 10 of these—substance, quality, quantity, etc.,—Kant understands them transcendentally, as fundamental forms of our cognition of things, so far as is possible a priori, and there are 12 of these—unity, plurality, totality, etc. Time too is a priori transcendental and does not belong to things in themselves but is one of two principles of pure intuition (the second one being space) that allow humans’ inner experience and vicariously an experience of external phenomena. Similar thoughts are those of Edmund Husserl (1859-1938) in his ontology, as an eidetic science about intentional objects in general with time as “world horizon” that allows a contact between humans and the whole of existence, whereas Bertrand Russell (1872-1970) as an analytic philosopher presumes that the structure of the world (atomistic facts) exposes itself to us through the structure and categories of language (atomistic propositions).
A stimulating conception of so-called critical ontology—realistically understood categorical analysis that investigates the forms of being gained by observation of reality and the relations between them—was created by Hartmann in the 20th century. Hartmann understands reality in its gradual unfolding from an inorganic level through organic and psychic levels to a spiritual level, whereby he presumes that these levels are categorically heterogeneous. Every one has specific categories that cannot be reduced to categories of other levels, neither downwards (criticism of materialism) nor upwards (criticism of idealism). All beings are understood to be dynamic as becoming; time is a more fundamental determination of reality than space.
The development of linguistically and mainly analytically orientated philosophy in the 20th century has led to specific reasonings about the ontological implications of language, which in the second half of the century resulted in discussions about so-called ontological commitments. According to the protagonist of this discussion and the author of the term, Willard van Orman Quine (1908-2000), the answer to the ancient ontological question “What exists?” does not come from philosophy but from science. Because acceptance of a scientific theory always presumes some ontology, it also therefore postulates some kind of entities that should exist if the theory is true. Quine also formulates a concrete criterion for specification of thus-formed ontological commitments of theories. If the theories are formulated in a standard language of first-order predicate logic, then for them “to be means to be the value of a bound variable.” However, as he points out, this criterion is not absolute—the given theory can be satisfied by several different ontologies, and it is not possible to definitely decide which one of them is valid (the principle of ontological relativity). Quine holds a perdurantist understanding of persistence of things in time, according to which a concrete particular is an aggregation of its temporal parts. Such an understanding is anchored in an eternalist conception of time that (unlike the pre- sentist one) supposes that all time dimensions, not only the present, are ontologically real.
See also Aristotle; Bergson, Henri; Descartes, Rene; Heidegger, Martin; Hegel, Georg Wilhelm Friedrich; Husserl, Edmund; Idealism; Kant, Immanuel; Materialism; Merleau-Ponty, Maurice; Metaphysics; Nietzsche, Friedrich; Parmenides; Plato; Plotinus; Presocratic Age; Russell, Bertrand; Schopenhauer, Arthur; Spinoza, Baruch de; Whitehead, Alfred North
Aristotle. (1993). Metaphysics. New York: Oxford University Press. (Original work 1st century CE)
Hartmann, N. (1953). New ways of ontology. Chicago: Regnery.
Heidegger, M. (1996). Being and time. Albany: State University of New York Press.
Inwagen, P. van. (2001). Ontology, identity, and moDalíity: Essays in metaphysics. Cambridge, UK: Cambridge University Press.
Quine, W. V. O. (1964). On what there is. In W. V. O. Quine, From a logical point of view. Cambridge, MA: Harvard University Press.