An actual occasion (also called an actual entity) is the fundamental unit of reality in Alfred North Whitehead’s process philosophy. Each actual occasion is a momentary event of experience that constitutes itself by prehending (grasping) the data of prior occasions, integrating that data through a process of concrescence, and achieving a determinate character — at which point it perishes as a subject and becomes an object available for prehension by subsequent occasions.
Actual occasions are not atoms in the classical sense. An atom is a simple, self-identical substance that persists through time; an actual occasion is a complex, self-constituting process that happens once and is done. Its identity is not given in advance but achieved through the process of becoming. What an occasion is depends on what it prehends and how it integrates those prehensions — which means that an actual occasion is constituted by its relations. This is the sense in which Whitehead’s metaphysics is a relational ontology: the relations are prior to the relata.
Each occasion involves two poles: a physical pole (the reception of data from prior occasions through physical prehension) and a mental pole (the evaluation of possibilities — what Whitehead calls eternal objects — that determine how the data is integrated). The mental pole is not consciousness; even the simplest occasions (an electron interaction, a molecular vibration) have a mental pole in the sense that they involve some degree of selection among possibilities. Consciousness is a late and derivative achievement, arising only in complex societies of occasions that achieve sufficient integration.
The enduring objects of everyday experience — chairs, stones, organisms — are not actual occasions but societies: structured patterns of occasions that achieve stability by repeating a common form across successive members. The chair does not persist; rather, a society of occasions inherits a chair-pattern from its predecessors.
Related terms
- Prehension — how occasions grasp the data of other occasions
- Concrescence — the process by which an occasion becomes determinate
- Eternal object — the possibilities that shape concrescence
- Event — the broader category
- Process — the primacy of becoming
- Substance metaphysics — what actual occasions replace