Anaxagoras, as understood by Marmodoro, is a maverick metaphysician. He is the first ante litteram gunk lover, and the gunk which he envisions is a collection of non-material, yet physical, powers (9). Most scholars will agree that Anaxagoras is an interesting theorist (equal in stature to, say, Empedocles or Xenophanes), but, through Marmodoro’s lens, Anaxagoras is all the more so: he is “profoundly original” and the study of his theory is “of value . . . for expanding our present philosophical horizons” (1 and 188).
On Marmodoro’s account, fundamental kinds within Anaxagoras’ system are infinitely divisible (or, more forcefully, infinitely divided). So, Anaxagoras’ physics is wholly non-atomic. Further, in contrast to the small cadre of modern metaphysicians who dabble with theories of material gunk, Marmodoro’s Anaxagoras conceptualizes a universe that is filled with only qualitative gunk. His world lacks matter: it lacks substance (84-5). On Marmodoro’s interpretation, Anaxagoras’ cosmos is stuffed with an infinite variety of quality-tropes (97). These tropes are instances of opposite physical properties, such as the hot and the cold, the wet and the dry, the bright and the dark, and the dense and the rare (12-17). The quality-tropes are vanishingly small, approaching zero extension as a limit (88-90). Also, in light of Anaxagoras’ No-Least Principle (NLP), tropes of each opposite-type are collocated (or co-present) in every region of the universe: no matter how small the region, not a single type of trope is ever excluded from that region (54-60 and 90-2). According to Marmodoro, Anaxagoras’ tropes are unceasingly active causal powers (31-6). The bright, as an example, is always actually bright and neither the bright nor any other quality-trope is ever potentially bright. In addition, according to Marmodoro, Anaxagoras’ power-tropes do not change anything else in the cosmos. Each plays only a constitutional-causal role (36). Each ‘bit’ of the bright, say, is bright and, when more instances of the bright come to occupy the same spatial region, therein the bright increases in density, and the brightness of the region increases in intensity (66). According to Marmodoro, all change, for Anaxagoras, is “reducible to spatial movement of tropes” (43). On this account, Anaxagoras accepts Parmenidean constraints on change, prohibiting creation, generation, and alteration, but not motion (24-31). The hot manifests hotness, but it does not (transitively) heat and the cold manifests coldness, but is does not (transitively) chill. Instead, when an ‘item’ is heated (/chilled) this is caused by an influx of hot-tropes (/cold-tropes) coupled with an egress of other tropes—most importantly an egress of cold-tropes (/hot-tropes). Regarding stuffs (e.g. earth, aether, and air) and the relation of stuffs to the qualitative opposites, Marmodoro argues that Anaxagoras is a phenomenal emergentist, a perceptual relativist, and an ontological mereologist (15 n. 5, 29-30). Earth, as an example, is not a legitimate kind: it is neither a primitive / fundamental kind nor a derived kind. Rather, earth becomes apparent to us through our perceptual powers, when concentrations of the dense, the wet, the cold, and the dark reach critical densities within a given spatial region. Ontologically, earth is not: earth may be phenomenologically apparent yet, in respect to being, there are only tropes. (Let us say ‘earth by convention, air by convention, but in reality bundles of tropes’.) According to Marmodoro, Anaxagoras codifies his stance on critical density (i.e. a level of density which may trigger phenomenal emergence) with the Preponderance Principle (PP). PP is a quantitative standard that is meant to explain both how qualities become evident and how stuffs emerge. As examples, when the quantity of hot-tropes in a region exceeds that of cold-tropes, then the region is hot and when there is a preponderance of dense-tropes, wet-tropes, cold- tropes, and dark-tropes in a region, then earth appears in that region. For Marmodoro, the situation is just a bit more complex: she distinguishes between a bare quantitative preponderance, which she affirms may be imperceptible, and a perceptible quantitative predominance, which relies on what she calls “the criterion of composition modulo perception” (64). Thus, on Marmodoro’s approach, Anaxagoras leaves a gap between purely quantitative preponderance and another, comparatively more robust sort of preponderance, with the latter (not the former) providing an explanatory ground for our coming to perceptual awareness of qualities and stuffs. Marmodoro’s aim, through most of the volume, is to advance, support, and defend the thesis that Anaxagoras “has a unique conception of gunk and a unique power ontology: power gunk” (9).
Marmodoro’s main thesis is bold: if she is correct, then matter does not really matter to Anaxagoras (17-20). Still, it is one of Marmodoro’s specific sub-theses that is likely to have the greater impact on the future of Anaxagorean studies. Marmodoro unearths an apparent inconsistency within Anaxagoras’ system. She argues: if primitives are subject to NLP and thus are wholly collocated in every spatial region (no matter how small), then primitives are continuum-dense: they have aleph-1 cardinality. (Here other interpreters might include stuffs, like earth and air, as primitives along with Marmodoro’s quality-tropes; yet, on this approach, the same difficulty would appear to remain.) On this interpretation, primitives of every type, in any spatial region, are as numerous as points on a line. Yet, we know that points on a line cannot vary in density. So Marmodoro infers that Anaxagoras’ primitives cannot vary in density within any spatial region. Still, as Marmodoro points out, Anaxagoras utilizes a theory of critical relational (and variable) density, codified in PP, to explain both the manifestation of quality-types and the phenomenal emergence of stuffs. So, Marmodoro concludes that NLP and PP are at odds. NLP is not consistent with preponderance: aleph-1 cardinality is not consistent with variable density. This is an intriguing result: Marmodoro shows that Anaxagoras may have put his foot in it.1 Still (and appropriately), Marmodoro does not take Anaxagoras to task over the apparent inconsistency. She notes: “Anaxagoras had mixed intuitions about both a countable and an uncountable infinity” and she finds that we moderns espy the difficulty owing to the gift of “Cantorian hindsight” (96, 100).
The greater share of the volume (chs.1-4) is devoted to the project of advancing the main thesis. Beyond discussion of the core physics of opposites and an assessment of the underpinnings of phenomenal stuffs, Marmodoro offers a chapter on Anaxagoras’ treatment of nous and seeds (ch. 5); plus a chapter on the Stoic theory of gunk (ch. 6). Maintaining a power-centric lens, Marmodoro argues that nous is “a bundle of cosmic and cognitive powers,” while the seeds are “powers for life” (136, 130). On Anaxagoras’ theory, nous introduces vortex motion within an infinitely extended primordial plenum: by instigating motion, nous brings about a redistribution of primitive bits and this redistribution results in the formation of our structured world (129). According to Marmodoro, the plenum holds a primitive and uncreated mix of quality-tropes—plus some stuffs (notably earth) and the complete catalogue of biological seeds. Marmodoro maintains that Anaxagoras pioneers a teleological approach to cosmology, by introducing nous as cognitive cosmic agent. She finds that, on Anaxagoras’ account, nous understands the local powers of opposites and seeds; plus, nous introduces motion in order to enable seeds to ‘germinate’: nous acts so that life may flourish (130). Thus, on Marmodoro’s interpretation, nous is responsible for the macrostructure of the cosmos, while seeds are responsible for “the organizational microstructures in the world, the organisms” (154). (Space does not permit discussion of Marmodoro’s treatment of Stoic gunk.)
Marmodoro, as I have suggested, advances a bold main thesis. Plus, she offers innovative and thought-provoking sub-theses. Marmodoro displays deep understanding of the secondary literature and she offers reasoned, even-handed, and efficient objections to competing interpretations. Through her investigation, Marmodoro invites the reader to take a fresh look: to reexamine and revalue Anaxagoras’ physical theory. The volume is a must read for specialists, a should read for students, and a deeply profitable read for anyone who is keen to learn about imaginative, creative, and complex approaches to ontology and cosmology.
With the hope of advancing debate, I close by highlighting a pair of Marmodoro’s more controversial claims and sketch some initial concerns.
1. Marmodoro maintains that stuffs, like earth, are not ontologically basic within Anaxagoras’ system (14, 17-20). Still, she acknowledges that, for Anaxagoras, earth is present in the primordial mix (62-3: see fr. B4b). I add that air and aether are present as well (see B1) and, as Marmodoro acknowledges, it may be that every type of stuff is present (66 n. 26). Here we find a difficulty. If Anaxagoras is a gunk lover, then he does not need stuffs in the mix: he has no reason to include stuffs in the mix. Further, if, on this interpretation, Anaxagoras aims to stock the mix with no more than the basic building blocks of the cosmos (basic stock is basic stock), then he must ban stuffs from the mix: he has every reason to exclude stuffs from the mix. So, problematically, on Marmodoro’s interpretation, (some) stuffs are temporally basic and uncreated (having existed from eternity within the mix) and yet these very items are not ontologically basic. At the least, this apparent lack of fit between the temporally basic and the ontologically basic suggests a need for renewed investigation into Anaxagoras’ rationale for positing the primordial mixture. (I note that temporally basic stuffs are in principle ‘perishable,’ whereas quality-tropes are not.) Some, for example, think that Parmenidean constraints demand that the mix be uniform at all levels of analysis: it cannot be x in one location, but not x in another. If this is right and stuffs are in the mix, then stuffs must be legitimate ingredients: Anaxagoras’ stuffs must be ontologically on par with his quality-tropes.
2. Marmodoro maintains that, for Anaxagoras, the large and the small (and other relatives) are quality-tropes (54-60, 122-5). Such a view may pose problems for Anaxagoras’ reliance on analysis by spatial partition. Take a given spatial partition: say, a region with a volume of one cubic meter. If, we were to stuff more of the cold into the region and extract lots of the hot from the region, then, for Anaxagoras, the region would get colder. Yet, for the same region, it would seem outlandish to propose that, for Anaxagoras, if we were to stuff more of the small into the region and extract lots of the large from the region, then the region would get smaller. Instead, the partition would stand, as given: it would remain a region with a volume of one cubic meter. On a related front, were Marmodoro to accept that, for Anaxagoras, spatial and relational qualities are not ontologically basic, this would alleviate some of the difficulties she faces when trying to explain how nous might be large or small and yet also “mixed with nothing [and] alone itself by itself” (B12: 131-6). For, if the large and the small are ontologically basic quality-tropes and if nous manifests largeness or smallness, then it would seem that nous is mixed: not unmixed.
1. The issue will require further study. Marmodoro is not the first to level a charge of inconsistency against Anaxagoras and many earlier charges have been shown to be erroneous. As an example, F. M. Cornford argues that Anaxagoras’ Everything-in-Everything Principle (EE-P) is not consistent with his Principle of Homoeomereity (PH) (‘Anaxagoras’ Theory of Matter, Classical Quarterly 24, 1930, 14-30 + 83-95 at 14). G. B. Kerferd later diagnoses the error in Cornford’s reasoning (‘Anaxagoras and the Concept of Matter Before Aristotle’ in A. Mourelatos, ed., The Pre-Socratics: A Collection of Critical Essays, Princeton University Press, 1974, 489-503 at 49) and most scholars now accept that EE-P and PH are consistent. It has been shown that those who maintain otherwise may have an inaccurate understanding of PH (see J. Sisko, ‘On the Question of Homoeomereity in Anaxagorean Physics’, Apeiron 42, 2009, 89-104).