Marmodoro, A. 2021. Forms and Structure in Plato’s Metaphysics. Oxford/New York: Oxford University Press. ISBN: 978-0-197-57715-8. 232 pages.

Anna Marmodoro’s Forms and Structure in Plato’s Metaphysics is a historical analysis of Ancient Greek philosophy and its influence on contemporary metaphysics. While the book is essentially historical, it delves into complicated metaphysical topics, making it of interest to readers in both the history of philosophy and metaphysics fields. Because my background is in the history of philosophy, I primarily read Marmodoro’s book through a historical lens. However, Marmodoro makes it clear that she does not wish to participate in the scholarly debates over the historicity of Plato’s dialogues. Instead, she treats the dialogues at “face – value,” in that the ideas expressed within are taken to be Plato’s own personal commentary and philosophy (10–11).

Readers should be aware that the book has numerous passages in the Ancient Greek language from Anaxagoras, Plato, Aristotle, and various Pre – Socratic philosophers. While the Greek of Anaxagoras and Plato is fairly simple to read with a basic grasp of the language, closer familiarity with Ancient Greek language and philosophy will maximize understanding. For this reason, the book is probably best suited for advanced graduate students or those specializing in Ancient Philosophy, Classics, or History. That said, Marmodoro does a good job of filling in the gaps so readers with no knowledge of Greek can still follow along.

As the title suggests, Marmodoro analyzes the concept of “Form”¹ in Plato’s metaphysics. Ultimately, this concept is about “properties,” as discussed in contemporary metaphysics. To Plato, these properties are viewed as universals, as all Forms are in Platonic dialogues, meaning that they can be shared by different objects (in typical cases).² A common view is that Plato’s predicates get their meaning from properties, universals, Forms, and other analogous concepts. So, in the sentence, “The house is beautiful,” there is something about the subject, “the house,” that is shared by all things described by the predicate “beautiful.” Thus, “beautiful,” considered as a property, gets some meaning from whatever this universally shared aspect is. To explain this point in Platonic language, if “the house is beautiful” is a true statement, then the house is said to “partake in” the Form “Beautiful.”

Much of Forms and Structure in Plato’s Metaphysics is concerned with explaining what it means for Plato to hold the view that material things “partake in” Forms. It tackles several questions, such as: What is required for something to partake in a Form? Do Forms have parts? If they have parts, then how many? If Forms are immaterial properties, then how do they interact with the physical world? How does Plato’s conception of the Forms change (or remain the same) throughout his life? Marmodoro’s thesis is that Plato’s metaphysical views were influenced by Anaxagoras and that by exploring this influence we can answer the above questions to varying degrees. For brevity, I will aim to provide only a general overview of Marmodoro’s unique attempts to answer some of the questions above.

The Theory of Forms changed throughout Plato’s works, and Marmodoro regards many of the resulting inconsistencies as due to Anaxagoras’s influence. Interestingly, Anaxagoras is not commonly considered to be one of Plato’s major influences. For instance, the Stanford Encyclopedia of Philosophy page on Plato’s metaphysics makes practically no mention of Anaxagoras, instead citing Heraclitus, Parmenides, and Socrates as Plato’s primary influences (Silverman 2014). Marmodoro explains that because Ancient Greeks did not cite sources as we do, and rarely quoted others directly, we need to examine what Plato says in comparison with Anaxagoras’s own words and ideas. As the book aims to show, Plato’s metaphysical claims are often referential to Anaxagoras without naming him (83, fn. 2). Marmodoro argues that Plato draws on Anaxagoras for two principal reasons: (1) the explanatory power of Anaxagoras’s ideas, and (2) how well these ideas fit within Plato’s own Theory of Forms (156). These reasons seemingly influenced Plato to change aspects of his own metaphysics.

The first third of Marmodoro’s book provides the details of Anaxagoras’s metaphysics, explaining how his system came to be, who inspired his views, and how his metaphysical commitments importantly differed from other philosophers. The middle part of the book explores Plato’s metaphysics and how the Theory of Forms can be compared and contrasted to Anaxagoras’s metaphysics. The goal of this section is largely to demonstrate how Anaxagoras’s views influenced Plato’s conceptions of Forms, properties, and causal powers. The final third serves as a proposed explanation of peculiarities found in Plato’s later dialogues, especially the Timaeus and Sophist. In particular, it explains why Plato’s Theory of Forms in his late period differs drastically from the theory as presented in his middle and late period works. One major aim of the book is to explain why the Theory of Forms shifts from only including one class of Forms as in the Republic and Phaedo, to later positing “Great Kinds” – second – order forms that exist over and above the Forms, as in the Sophist – and culminating with his concept from the Timaeus of the paradeigma as a single Form that governs all other Forms.

Marmodoro dedicates much of Chapters 1 and 2 to explaining the metaphysical properties and entities in Anaxagoras’s system, particularly his concept of the “Opposites.” Typical examples of Opposites include “hot and cold,” “wet and dry,” “sweet and bitter,” and so on. There is debate over the nature of the Opposites and how they should be conceived as properties. But Marmodoro interprets all properties in Anaxagoras’s ontology as being reducible to Opposites. That is, the Opposites explain how objects come to have certain properties, particularly physical ones. For instance, in “the soup is hot,” the hotness of the soup is a property that reduces to Heat, the Opposite property of Cold. But how did the soup acquire this property? Marmodoro’s answer is that Opposites are causal powers. In other words, causes are contagious and pass on properties by themselves having said property. Marmodoro calls this the “contagion principle” (25–28). For example, if I am covered in a fresh coat of red paint and I touch a chair, I pass on some red paint to the chair. I have the property “redness” and pass it on to the chair when I interact with it. It can be helpful to think of Opposites (and Forms)³ as interacting with the world in this way. From the contagion principle, Marmodoro concludes that properties for Anaxagoras are made – up (constituted) by the same parts as their subject (29). This idea establishes the groundwork for Chapter 4, in which Marmodoro argues that constitutional overlap is also a feature of Plato’s Forms.

Having introduced important concepts from Anaxagoras’s metaphysics in the first two chapters, Marmodoro uses the remaining chapters to argue that these concepts influenced Plato’s metaphysics. However, Marmodoro acknowledges that Plato is often considered a critic of Anaxagoras. The latter interpretation, she claims, is largely due to the fact that Socrates explicitly argues against Anaxagoras in the Phaedo regarding a proposed explanation of intentional action. Since Plato does not argue against other aspects of Anaxagoras’s philosophy (especially ones relevant to this book), Marmodoro argues that we should not conjecture that Plato disagrees with Anaxagoras entirely and may be said to approve of aspects not mentioned. This argument presents one unfortunate shortcoming of the book. While many comparisons between Anaxagoras and Plato are interesting, the alleged influence of the former is sometimes unconvincing. For instance, Marmodoro argues that Parmenides influenced Anaxagoras, who then influenced Plato. But it is sometimes unclear why readers should agree with her claim that Plato was more influenced by Anaxagoras than by Parmenides. She also never explicitly mentions Heraclitus in her book, even though his concept of “flux” is taken to be an important influence in Plato’s development of the Theory of Forms. A brief chapter carefully examining this topic would have made her claims of Anaxagoras’s influence more convincing.

Chapter 3 is dedicated solely to Plato’s Forms, especially how they are conceived as causal powers. Marmodoro cites the “Eleatic Principle” as evidence for this claim (66). The Eleatic Principle is derived from Plato’s explanation of Forms in the Sophist as, “Those things which amount to nothing other than power,” (Sophist 247e1–2). Marmodoro develops the further view that not only are Forms causal powers, but “transcendent causal powers.” That is, Forms, unlike Anaxagoras’s Opposites, are ideal entities that are not themselves physical objects but exist prior to the existence of physical objects. Naturally, a problem arises: if the Forms are transcendent (i.e., aspatial and atemporal), then how can they have causal efficacy on objects in the physical world? To borrow an example from the book, “in Plato’s universe, sensible objects are, e.g. hot by having within their constitution parts of the form of Heat, which is transcendent,” (65 & 82). In this sense, Forms ascribe properties to objects. Lava is hot because lava is constituted by the Form called “Heat.” Marmodoro argues that here Plato is introducing the “problem of instantiation of properties” (82). The problem proceeds as follows: we consider heat to be a physical property: we can feel it, measure its temperature, increase or decrease it, and so on. Yet, how can a transcendent, non – physical entity like the Form “Heat” or “Hotness” be responsible for a physical object having certain properties (e.g., the object being hot)? Plato does not provide an explicit explanation. According to Marmodoro, this is because an answer can be found implicitly in the Timaeus. Marmodoro conjectures that Plato is committed to the view that transcendent entities (including the Forms) have normative influence over physical entities (79). In other words, although Forms are aspatial and atemporal, it is a fact of their nature that they can affect physical things. This topic is explained in greater detail in chapter 7.

“Constitutional overlap,” introduced in Chapter 1, is the topic of closer examination in Chapters 4 and 6, which detail how constitutional overlap in Anaxagoras’s metaphysics was intentionally inherited as a central feature of Plato’s metaphysics. Plato’s conception of Forms requires that they are immutable, that is, they do not change over time nor each time they are instantiated. In order for Forms to be immutable, they must not have parts, according to Plato’s “Affinity Argument” in the Phaedo (78b–84b). Yet, elsewhere Plato states that in order for objects to partake in Forms, the objects must possess part of the Form they partake in. Thus, it seems that Plato holds the contradictory view that Forms cannot be composite entities yet have parts. To resolve this conflict, Marmodoro proposes that Plato’s conception of partaking means “partaking in extrinsic parts of Forms.” She motivates this interpretation by referencing the notion of Cambridge change: “Oregon is north of me,” contains a true predicate about Oregon while I am in California. However, next week if I am in Washington then “Oregon is north of me,” is not a true predicate about Oregon (it is south of me). However, the change that occurs is not due to some changing intrinsic property of Oregon. The change is due to an extrinsic property changing, namely, my location. Similarly, Marmodoro argues, when an object partakes in a Form, we can think of the object as partaking in a “Cambridge partition” of the Form that overlaps with the object without itself being intrinsically changed (112). Plato uses an analogy of a sail on a boat: The sail’s shadow covers two people at once, one part over one person, another part over a different person. Yet, the sail itself is not intrinsically being divided into parts (Parmenides 131c2–3). In other words, the sail overlaps each crewmate, but it does not follow that each crewmate is an intrinsic part of the sail. Perhaps tomorrow there will be a different crew manning the ship, in which case the sail is the same, but different crewmates partake in the sail’s shadow. This example also explains how constitutional overlap applies to Plato’s Forms. For example, the Form of Beauty (or more accurately, a partition of the Form) can overlap with both a work of art and a mathematical theorem on different occasions without itself being changed.

In the final section of Chapter 5, Marmodoro applies Anaxagoras’s contagion principle (covered in Chapter 1) as a novel way of interpreting Plato’s “Third Man Argument” from the Parmenides (132a–b). As the argument demonstrates, a problem arises when considering properties such as the Forms as causal powers. This issue is especially pertinent if Forms utilize the contagion principle to instantiate properties in objects, as Marmodoro contends they do. For example, the Form of Beauty₁ is one form which many things partake in. Sunsets, people, artwork, formulas, and so on, may be instantiations of Beauty₁. Thus, sunsets, people, artwork, and formulas make up a plurality of beautiful things (P1). However, recall the contagion principle which states that properties are instantiated in things by Forms themselves having those properties.⁴ If this is the case, there must be another plurality of beautiful things (P2) which includes: sunsets, people, artwork, formulas, and the Form Beauty₁. The principle of non – identity states that no Form is identical to anything that partakes in it. Due to this principle, there must be another Form (Beauty₂) that accounts for P2, and so on into an infinite regress.

Since the contagion principle fails to remedy the regress presented by the Third Man Argument, a solution is needed in order to make sense of the origin of Forms. In Chapter 7, Marmodoro proposes that the solution to this problem has already been provided by Plato in the Timaeus with his concept of the paradeigma and a distinction between Being and Becoming (189–191). Forms are entities subject to Becoming, they not only cause an object’s becoming hot (for example), but also themselves become hot. On the other hand, the paradeigma is a higher Form which Plato explicitly describes as not being subject to Becoming. The paradeigma exists without any cause, subject only to Being, and is responsible for the causation of all other Forms. Conceiving of the paradeigma as Plato’s solution to the Third Man Argument is a novel interpretation from Marmodoro with lasting consequences. If this interpretation is true, it serves as concrete evidence that Plato’s Timaeus is in fact one of his late dialogues. While this placement in the timeline of his works is not uncommon, some argue that the Timaeus may be an early dialogue. Others hold it to be a late dialogue, but do not have much evidence to support this claim. Yet if Marmodoro is right, we can clearly see a progression in Plato’s Forms from his earlier dialogues (especially from the Phaedo and the Parmenides) to his late period.

Forms and Structure in Plato’s Metaphysics is by no means an introduction to Plato’s philosophy or to metaphysics. However, those lacking a background in metaphysics should not be dissuaded from reading the book. With a basic understanding of Plato’s Theory of Forms and some metaphysical terminology, a reader will find that the book contains valuable analysis that encourages further investigation into Plato’s metaphysics. A virtue of the book is that each chapter can be read individually, and within each chapter are sub – headers that further demarcate “smaller” topics covered. So, it benefits academics interested in researching particular topics, such as, Forms as causal powers, Anaxagoras’s conception of nous, Bundle Theory, or the partitioning of properties (among many other topics covered relevant to history and metaphysics). Further, scholars curious about the Anaxagoras – Plato connection may find interest in some of the conclusions developed by Marmodoro in this text and her other writings on this topic. This connection is sprinkled throughout the book, although I find myself wanting more pages dedicated solely to this topic since it is stated as a primary aim of the book. Nevertheless, Marmodoro makes interesting comparisons between the two thinkers that not only inspire further investigation and debate, but also demonstrate the relevance of Plato’s views in contemporary metaphysics.