In Process and Reality Whitehead writes:

…we always have to consider two meanings of potentiality: (a) the ‘general’ potentiality, which is the bundle of possibilities, mutually consistent or alternative, provided by the multiplicity of eternal objects, and (b) the ‘real’ potentiality, which is conditioned by the data provided by the actual world. General potentiality is absolute, and real potentiality is relative to some actual entity, taken as a standpoint where the actual world is defined. It must be remembered that the phrase ‘actual world’ is like ‘yesterday’ and ‘tomorrow,’ in that it alters its meaning according to standpoint. The actual world must always mean the community of all actual entities… (65)

My thought process is murky today, so I just wanted to throw out a few points in response to this passage as placeholders for future thought. It seems to me that Whitehead’s distinction between general potentiality and actual potentiality is useful in articulating what Deleuze sort of ontological work Deleuze’s category of the virtual is trying to do. Suppose we take a canonical example of potentiality from the Aristotlean tradition: the acorn. It is said that the acorn has the potential to become an oak tree. However, this would be an example of general potentiality. When we think of the acorn in this way, we are thinking of the acorn abstractly, divorced from its environment or the way in which it is related to other entities. The question remains: will the acorn become an oak tree? We have no idea. We only know that the acorn has the potential to become an oak tree. I am still unclear as to what Whitehead has in mind by “eternal objects”, so hopefully I am not distorting his conception of general potentiality too much.

There are conditions under which the acorn has the potential to become an oak tree and conditions under which the acorn does not have the potential to become an oak tree. These conditions do not belong to the internal constitution of the acorn, but rather are defined by the relations the acorn entertains to its environment: soil conditions, mineral conditions, light conditions, heat conditions, water conditions, air conditions, etc. Whitehead would say that the acorn must “prehend these other actual entities so as to concress into an oak tree.” That is, it must integrate the world about it so as to creatively actualize itself as an oak tree. This process is creative in that it will be a novel event each time it takes place. As Leibniz famously observed, no two leaves are exactly alike. The reason for this is that each leave, each oak tree, integrates the “data” of its environment in its own unique way. In this connection, Whitehead is quick to emphasize that real potentiality is closely connected to place and time (he develops an elaborate and original account of space and time that I cannot develop at this moment):

Actual entities atomize the extensive continuum [the real potentials of the world]. This continuum is merely the potentiality for division; an actual entity effects this division. The objectification of the contemporary world merely expresses mutual perspectives which any such subdivision will bring into real effectiveness. These are the primary governing data for any actual entity; they express how all actual entities are in solidarity in one world. With the becoming of any actual entity what was previously potential in the space-time continuum is now the primary real phase in something actual. For each process of concrescence a regional standpoint in the world defining a limited potentiality for objectifications, has been adopted.

The acorn does not possess the potential to become an oak tree on the moon. Nor does the acorn have the potential to become an oak tree in the Sahara desert. If these conditions are not met, then the acorn is not actualized and no processes of individuation take place. These latter conditions thus constitute real potentiality. This, incidentally, would be the problem with political theories such as we find in figures like Rawls. They only speak of general potentiality and therefore give no account of whether or not such egalitarian ideals have the potential to be realized in really existing situations. As such, they remain entirely abstract. We can ask the question of why such theories became thinkable at such and such a time and what potentialities of their own they produce, but there can be no honest question of these theories dealing with concrete situations. Such are the philosophies of the armchair. These potentials always have their somewhere and their somewhen. These potentials are, moreover, limited depending on the conditions governing the situation. As such, they function as the sufficient reason for the actualized occasion, or the reason for the actuality’s being.

Real potentiality would thus consist of the real potentials population a situation at a given point in time. It is for this reason that Whitehead is quick to emphasize that the term “actual world” is an indexical like yesterday or tomorrow. It is an indexical in the sense that its content perpetually changes. Similarly, relations among actual entities are perpetually changing, thus leading to transformations in the real potential of situations. With the actualization of virtual potentials, new potentials are produced that are, in turn, opportunities for further actualizations. All of this comes very close to what I’m trying to get at when speaking of “constellations“. A constellation refers to the real conditions encountered within a situation, and is committed to the thesis that thought must proceed from these conditions rather than from universalizing abstractions that ignore the actual world.

It seems to me that all of this resonates very closely with Deleuze’s concept of the virtual and the concerns that motivate this ontological category. Discussing the virtual in Difference and Repetition, Deleuze writes,

We opposed the virtual and the real: although it could not have been more precise before now, this terminology must be corrected. The virtual is opposed not to the real but to the actual. The virtual is fully real in so far as it is virtual. Exactly what Proust said of states of resonance must be said of the virtual: ‘Real without being actual, ideal without being abstract’; and symbolic without being fictional. Indeed, the virtual must be defined as strictly a part of the real object– as though the object had one part of itself in the virtual into which it plunged as though into an objective dimension… The reality of the virtual consists of the differential elements along with singular points which correspond to them. The reality of the virtual is structure. We must avoid giving the elements and relations which form a structure an actuality which they do not have, and withdrawing from them a reality which they have. We have seen that a double process of reciprocal determination and complete determination defined that reality: far from being undetermined, the virtual is completely determined. When it is claimed that works of art are immersed in a virtuality, what is being invoked is not some confused determination but the completely determined structure formed by its genetic differential elements, its ‘virtual’ or ’embryonic’ elements. (DR, 208-209)

Deleuze’s account of structure requires an extended commentary that I cannot provide at the moment, as it diverges markedly from “structuralist” conceptions of structure, allowing for dynamism, development, and evolution. What Deleuze is striving to think with the virtual is the concreteness of a situation and the differential relations that an entity entertains with its milieu in undergoing development. What, then, are these “genetic differential elements”, these “embryonic elements”, if not the real potentials that haunt a situation? The question then becomes one of how these real potentials might be awoken.