The following is a lecture from a course I’m currently teaching called Whitehead’s Adventure in Cosmology: Toward a Physics of the World-Soul. Watch the PBS Space Time video first for context.
“The animal body is only the more highly organized and immediate part of the general environment for its dominant actual occasion [i.e., its consciousness], which is the ultimate percipient […] According to this interpretation, the human body is to be conceived as a complex ‘amplifier’ — to use the language of the technology of electromagnetism. The various actual entities, which compose the body, are so coordinated that the experiences of any part of the body are transmitted to one or more central occasions to be inherited with enhancements accruing upon the way, or finally added by reason of the final integration. The enduring personality is the historic route of living occasions which are severally dominant in the body at successive instants. The human body is thus achieving on a scale of concentrated efficiency a type of social organization, which with every gradation of efficiency constitutes the orderliness whereby a cosmic epoch shelters in itself intensity of satisfaction.”
-Alfred North Whitehead, Process & Reality, p. 119
1) Actual Occasions: the final realities of which the world is composed. Actual occasions are not “things” in space-time, but spatiotemporal events. Space-time is emergent from the relationships among actual occasions.
2) Eternal Objects: the “pure potentials” that characterize the experience of actual occasions. Eternal objects can be both quantitative/mathematical or qualitative (e.g., colors, sounds, tastes, etc.). They characterize the “how” of experience and have thus been described as “adjectival” and “adverbial” by Whiteheadian scholar Steven Shaviro Eternal objects determine how actual entities relate to one another and “enter into each others’ constitutions” (PR, 148-149). An eternal object does not involve any necessary reference to a specific occasion of experience: an experience of two chairs and an experience of two cats are quite distinct experiences, but both ingress the same eternal object, “twoness,” that captures an identical essence participant in both situations. Eternal objects “ingress” into actual occasions, but don’t themselves cause actual occasions (Heller misleadingly claims that “an eternal object is a pure possibility which causes an actual entity to be what it is”; Whitehead is very clear that actual occasions are the only causes or reasons).
How to think about the relation between actual occasions and eternal objects: Actual occasions, as the final realities of which the universe is composed, are self-creating buds of experience, each one uniquely itself even while it remains internally related to every other occasion in the creative community of the universe. Occasions are interrelated by way of the pattern of eternal objects characterizing for each of them the quantitative and qualitative aspects of the other occasions in their community. Eternal objects “interpret [occasions], each to the other,” such that they come to find themselves related to one another in an extended space-time continuum according to certain more or less stable geometric principles (SMW pgs. 137,145).
3) Prehensions: If we ask what actual occasions are made of, the answer is “prehensions.” Prehensions are feelings that come in two pure forms: physical prehensions of already actualized occasions in our causal past, and conceptual prehensions of as yet unactualized possibilities (or eternal objects). Prehension is what allows actual occasions take one another up into their own being. It replaces the Cartesian notion of “representation,” whereby a mind was said to internally picture an external object. When an actual occasion prehends another occasion, it is not just constructing picture of that occasion, thus relating to it only indirectly; rather, it is feeling that occasion’s feelings directly. Each actual occasion is in some sense nothing but the multiplicity of prehensions of other occasions (as characterized adverbially by eternal objects) which it unifies. But in another sense, as a self-unifying creature, an occasion not only prehends and reiterates the realized spatiotemporal pattern of the settled past, it adds a novel actualization of value—itself—to the ongoing evolution of the universe.
4) Societies: Actual occasions group themselves together into societies. A society is a group of actual occasions that ingresses some shared defining characteristic or set of characteristics. These groupings are both spatial and temporal. Galaxies, stars, planets, organisms, and souls are all examples of societies of actual occasions.