Ontology is the study of “being as being,” independently of its particular determinations.
In modern philosophy, a distinction is often made between the study of being as essence — causes and laws of being (essentialism) — and the study of being as existence, i.e., concrete, singular beings (existentialisms).

Because being transcends its particular determinations (a determined being is an entity), onto– (being)-logy (science) is not fundamentally different from meta– (beyond)-physics (beings).

Nevertheless, Kantian and Heideggerian critiques have shown that ontology — like metaphysics — may degenerate into a closed system; it then loses its openness to Being (Wesen) and becomes reduced to the study of entities (Dasein), to the point that God Himself is reduced to the status of a first entity (onto-theology).

To avoid such conceptual ambiguities, one generally prefers to speak of metaphysics whenever the inquiry concerns what is beyond being rather than being, or being rather than entities.

More precisely

The term ontology appears in the 17th century, but the discipline itself goes back to ancient Greek philosophy.

For Plato, to know being is to gain access to the intelligible Forms.
For Aristotle, ontology becomes the science of being as being, distinct from the particular sciences, each devoted to a specific domain.

In the medieval tradition, ontology articulates the decisive distinction between
— essence (what a thing is), and
— existence (the fact that it is).
For Thomas Aquinas, Being as Act (actus essendi) is the summit of intelligibility and directs ontology toward theology.

Modernity divides ontology into two orientations:
— essentialism (being as quidditas), and
— existentialism (being as the factual condition of the subject).

With Heidegger, ontology becomes fundamental ontology:
it no longer seeks to determine being conceptually but to question the meaning of being from the standpoint of Dasein, the only entity capable of questioning being.
Heidegger also highlights the danger of onto-theology: the reduction of the Absolute to a highest entity among beings, which betrays its transcendence.

We can therefore distinguish:
— the ontic, concerned with entities;
— the ontological, concerned with being;
— and metaphysics, concerned with what lies beyond being, the Supreme Principle or Non-Being.

Thus, ontology occupies an intermediate position:
it surpasses the study of entities but does not necessarily reach the Absolute Principle.
Authentic ontology therefore requires an opening to metaphysics; otherwise, it collapses into closed conceptual discourse, deprived of its foundation.

For further reading

  • Plato, Sophist; Parmenides — On being, non-being, and Forms.
  • Aristotle, Metaphysics — Definition of being as being.
  • Thomas Aquinas, De ente et essentia — On the distinction essence / existence; act of being.
  • Duns Scotus, Ordinatio — On the univocity of being and formal distinctions.
  • Kant, Critique of Pure Reason — On the critique of being as a predicate; limits of metaphysics.
  • Heidegger, Being and Time (1927) — Fundamental ontology; Dasein.
  • Jean Beaufret, Dialogue avec Heidegger — On Heidegger’s ontological thought.
  • Jean Borella, Amour et Vérité (Paris, L’Harmattan, 2011) — On intelligibility, intelligence, and the unfolding of being.
  • Bruno Bérard, Metaphysics for Everyone (Angelico Press) ;
    — fr. Métaphysique pour tous (Paris, L’Harmattan, 2022)
    — it. Sui sentieri della metafisica
    — es. ¿Qué es la metafísica?
    — de. Was ist Metaphysik?
    On degrees of being, ontology, and metaphysical surpassing.