Harman credits Whitehead for being one of the few daring philosophers “to venture beyond the human sphere” (Guerrilla Metaphysics, 190). Both thinkers share a commitment to anthrodecentrism. They de-center the human by insisting upon a flat ontology, a theory of Being wherein every being exemplifies the same set of metaphysical categories, whether that being be God, or human, or “the most trivial puff of existence in far-off empty space” (Process and Reality, 18). There are no special exceptions in ontology, no “highest being” exempt from reality’s rules (or from reality’s unruliness). Whitehead was already explicit about the need to avoid paying metaphysical compliments to an ontologically exceptional being. Similarly, he sought to untwist the Kantian reversal that made the special cognitive and perceptual modes of access typical of conscious human beings into the transcendental condition underlying relations of all types. On Whitehead’s reading, Kant privileged perception in the mode of “presentational immediacy” and ignored or at least sidelined the deeper and more ontologically relevant perceptual mode of “causal efficacy.” “Presentational immediacy” displays reality in a way amenable to representational analysis, showing only the more or less clear and distinct surfaces of the world as they are presented to a reflective subject here and now. It is the end product of a complex process of unconscious prehensive unification in our organism and nervous system. “Causal efficacy” unfolds behind the scenes of this Cartesian theater in the unrepresentable depths of reality, carrying vague emotional vectors from the past into the present. Perception in the mode of presentational immediacy is punctual (hence its relative clarity and distinctness); perception in the mode of causal efficacy is transitional (hence its vagueness). Presentational immediacy allows for intentional consciousness, the subjective capacity for attentional directedness toward the eidos of objects; causal efficacy, in contrast, is prehensional, the presubjective capacity to inherit the affective influences of objects. The former mode requires that a mind remain at a distance from things, relating to their essence rather than sensing their causal presence, while the latter implies the internalization of things, the intimate assimilation of their past being into our present becoming. Whitehead’s alchemical distillation of consciousness reveals an experiential structure even deeper than intentionality, a ontologically basic level of experience shared in by all relational beings. If anything is transcendental, it is not human intentionality (as Kant argued), but cosmic prehensionality. As Harman puts it, Whitehead made it possible for us to “speak in the same way of the relation between humans and what they see and that between hailstones and tar” (Prince of Networks, 124).
As Shaviro makes clear, Whitehead’s concept of “prehension” is meant to include both causal and perceptual relations (The Universe of Things, 29). He invented the concept in an attempt to subvert the bifurcation of nature between mental images and material impacts, between nature as it appears before us (“the dream”) and nature as it is thought to be the cause of appearance (“the conjecture”). Prehension allows us to envision, again in Harman’s words, “a world in which the things really do perceive each other” and are not just perceived by us (GM, 52).
The prehensional basis of all object-relations implies that “detached, self-contained local existence” (i.e., simple location) is impossible, since in each act of prehension “the environment enters into the nature of” the prehending thing. This is not to say that things have prehension as a capacity; rather, in Whitehead’s scheme, a thing or actual entity is a momentary unification of multiple prehensions. Actual entities do not have prehensions (as when substantial minds are said to have accidental perceptions); rather, they are prehensions. It is regarding the issue of the interrelation of all things that Whitehead and Harman begin to part ways. While Whitehead defends an image of the universe as a creatively evolving nexus of interpenetrating events, Harman paints the picture of “a universe packed full of elusive substances stuffed into mutually exclusive vacuums” (GM, 76). Shaviro neatly sums up the disagreement: “Whitehead opposes correlationism [and anthropocentrism] by proposing a much broader–indeed universally promiscuous–sense of relations among entities,” while “Harman opposes correlationism by deprivileging relations in general” (tUoT, 30).
Harman rejects Whitehead’s relationalism for two reasons: 1) he worries it reduces ontology to “a house of mirrors” wherein, because a thing just is a unification of its prehensions of other things, there is never finally any there there beneath its internal reflections of others; and 2) he claims that an ontology based exclusively on internal relations, wherein entities are said to hold nothing in reserve beyond their present prehensional relation to the universe, cannot account for change or novelty. In such a universe, there would be “no external point of purchase from which structure could be transformed,” as Levi Bryant puts it (The Democracy of Objects, 209). As Shaviro is quick to point out, however, Whitehead was well aware of this potential objection (see page 35 of PR, for example), which is exactly why he amended his ontology sometime between his final editing of Science and the Modern World (1925) and Process and Reality (1929) so that becoming was understood to be atomic rather than continuous. A fair reading of Whitehead’s mature metaphysical scheme should acknowledge (despite a few inconsistent statements here and there) that his goal was to strike some balance between internal and external relations, precisely for the reasons put forward by Harman and Bryant.
In response to Harman’s first worry regarding an infinite regress of prehensions, I’d call his bluff and say that a truly aesthetic ontology (which he also claims to be seeking) would leave us with just such an infinite regress of appearances. A thing’s “style” or “allure” doesn’t need to be understood as emanating from some substantial core or fixed essence; we can also understand a thing’s “style” as Whitehead does in terms of the “enduring characteristic” realized by a historical route of actual occasions. There is nothing hidden from view by such outward qualities other than the occasion in question’s moment-to-moment subjective enjoyment of these characteristics. Which brings us to Harman’s second (I believe unfounded) worry about relational reductionism. Whitehead’s dipolar account of the process of experiential realization includes both a public moment of display and a private moment of withdrawal. Every drop of experience begins by taking up the “objectively immortal” data of its past. It then unifies this data into its own singular and private perspective on the world. It is this moment of privacy that most closely resembles Harman’s doctrine of withdrawal. The occasion in question is in this moment entirely independent of its relations. But as soon as this private, never before experienced perspective on reality is realized, it perishes into objective immortality, becoming publicly available for the next occasion of experience to inherit as it moves toward its own novel concrescent realization. “The many become one, and are increased by one.” Whitehead is able to make sense of change and novelty while at the same time preserving a non-reductive account of internal relations. It seems to me that Harman’s insistence on the irrelevance of evolutionary time for ontology is part of the reason he is unable to make sense of Whitehead’s attempted compromise (“The ontological structure of the world does not evolve…which is precisely what makes it an ontological structure” [GM, 24]). In effect, Whitehead’s entire process ontology can be understood as an imaginative generalization of evolutionary theory.
This difference regarding the metaphysical status of evolutionary time represents a deep divide between Whitehead’s and Harman’s otherwise similar ontologies. Shaviro, following Stengers (who was following Deleuze), reminds us that “the concepts a philosopher produces depend on the problems to which he or she is responding” (tUoT, 33). It seems as though the deep divide between Harman’s ontology of vacuum sealed objects and Whitehead’s ontology of interrelated organisms comes down to a question of taste. There is no going behind aesthetic taste to find some more rational justification to prefer one account over the other. As Fichte put it in his Wissenshaftslehre (although in the context of morality and not aesthetics), the kind of philosophy one adopts ultimately depends on the kind of person one is. Harman’s personal problem is to account for how relation is possible in a universe of vacuous actualities, while Whitehead’s was to account for how individuality is possible in a universe of interpenetrating actualities.
In the spirit of attaining to some wider point of view inclusive of both perspectives, Shaviro sums up the situation thusly:
“Harman’s difference from Whitehead, and his creative contribution to speculative philosophy, consists in the ‘translation’ of the deep problems of essence and change from one realm (that of relations) to another (that of substances). These two realms, oddly enough, seem interchangeable–at least in an overall anticorrelationist framework. Given that ‘there is no such thing as transport without transformation,’ the only remaining question is what sort of difference Harman’s transformation of ontology makes” (tUoT, 41).
Given the state of our present world, wherein “we are continually beset by relations, smothered and suffocated by them…where all manners of cultural expression are digitally transcoded and electronically disseminated, where genetic material is freely recombined, and where matter is becoming open to direct manipulation on the atomic and subatomic scales,” Whitehead’s problematic appears more and more relevant to our actual condition (tUoT, 33, 42).
Footnotes2Plato 
What do you think?