In a review of Iris Murdoch’s The Sovereignty of Good, Anthony Kenny famously averred that, while all contemporary philosophers revere Plato, most revile Platonism. There is no doubt some truth in this quip, but one may well wonder whose Platonism is being held up to scorn. Probably, the most likely target is the philosophical position of those who from the 18th century onward have come to be known as “Neoplatonists”. A different target, though more railed against in recent times, is Christian Platonism. A considerably more esoteric pejorative connotation is attached to the position in contemporary mathematics called “Platonism,” a position whose connection with Plato is rather remote, indeed.
Scott Berman has undertaken a most interesting project. In this monograph, he means to defend Platonism, as he understands it, shorn of all or most historical accretions. For Berman, Platonism is a theory of Forms, in particular a theory of the formal objects of scientific investigation. So, to put it simply, Berman argues that what all scientists—social scientists as well as natural scientists—are in fact doing is searching for laws or scientific truths, the manifestations of which alone are available to empirical investigation. So, it is the eternal truths of Platonism that make science possible. Many of these will be expressed as mathematical equations. The simple equation f=ma will be, if true, eternally true, based on the nature of force and mass and acceleration. Berman’s project is akin to that of Andreas Wagner’s project in The Arrival of the Fittest (2015). Wagner is an evolutionary biologist who argues that the almost impossible small evolutionary pathway from inorganic material to large mammals could only be realized if there were an eternal realm of real biologic possibilities, for example, a Form of a certain amino acid or a form of a certain arthropod, somehow or other guiding development through the unimaginably large number of evolutionary dead ends.
Berman’s austere Platonism, with a couple of desultory exceptions, even eschews references to Plato’s dialogues. He wants to focus on a philosophical position and not on exegesis. Fair enough. But he elaborates that position by making some questionable claims about Plato’s intentions or, more circumspectly, about the more defensible positions that Plato’s claims open up. For example, Berman vigorously denies that Plato defends (or, apparently, needs to defend, if he in fact did do so) grades of being. Plato, says Berman, thinks that Platonism holds that Forms exist in the same way that sensibles do. Thus, the eternity of Forms does not indicate a different category of being from the temporality of sensibles. This claim will not satisfy those familiar with the texts in which Plato seems to situate sensibles midway between the eternal and non-being. For example, at Rep. 478d5-9, sensibles are said “to be and not to be” at the same time, and this state is contrasted with the eternal and perfect being of Forms. Again, part of Berman’s defense of the indispensability of Forms for scientific knowledge is that sensibles are “bad candidates for knowledge”. Of course, what Plato actually says is that there is no knowledge of sensibles; knowledge is only of Forms. And here it matters that Plato uses the semi-technical term ἐπιστήμη. Berman seems to take “knowledge” in a sense according to which, roughly, there is knowledge of the sensible world, but it is not the best type of knowledge, something like bad violin playing. This is not Plato’s view nor does Berman attempt to show that it could or should have been his view.
The book has an entirely perspicuous structure and is clearly written with many helpful examples. An introduction sets out the argumentative strategy: show the insufficiency of alternatives to Platonism and then provide an outline of the core Platonic position, demonstrating how it answers satisfactorily all the questions that the competitors fail to answer or even address.
Chapter One, “An Argument Against Nominalism,” focuses on the position which holds that the data for which the theory of Forms is supposed to provide an explanation do not even exist. These data are real samenesses and differences in the sensible world. The reason these data are in need of an explanation is that the samenesses among things appear to belong to a category distinct from identity. Thus, two objects can be the same in color even though they are at least numerically different. The nominalist wants to insist, on empirical grounds, that sameness is not measurable or even observable as a category distinct from identity. If two things are the same that just means that they are identical; if they are not identical, then they are not the same. The central idea of Platonism, as Berman explains, is the introduction of the explanation for the possibility of sameness among things that are different. This is what eternal Forms do. But if there is no sameness, then no Forms are needed.
The central argument of this chapter is that nominalism fails because “an ontology restricted to concrete particulars would make science impossible” (p. 24). It hardly needs adding, however, that most (not all) proponents of nominalism do not believe that science is impossible. Berman adds an interesting argument to the effect that a commitment to evolution must account for the human ability to recognize kinds of stimuli, even though, according to the nominalist, there are no kinds, and so no explanation for why this ability has adaptive value. In this chapter, Berman also takes on what he calls “class nominalism” and “resemblance nominalism” both of which fail to account for the universality of scientific claims.
Chapter Two, “An Argument Against Contemporary Aristotelianism” attacks the view that universals are real, but nothing more than the spatiotemporal collection of their instances. On this view, there can be no uninstantiated universals. Berman argues that this view is at odds with the scientific presumption of the existence of uninstantiated possibilia. He provides some illuminating examples from the history of science to show that actual scientific theorizing often presumes the existence of things that do or may turn out to be actual. In effect, scientists often think about essences independently of their knowledge of whether or not these exist. This, for Berman, counts decisively against the quasi-Aristotelian view that universals are always concretely instantiated. Berman’s conclusion is that science needs to liberate universals from their supposed spatiotemporal status, which of course will be the setup for his later defense of Platonism (p. 80).
Chapter Three, “An Argument Against Constructivism,” has a rather easy time in showing the incoherence of a view that all of the “commonalities” we experience are mind-dependent. Berman’s strategy here is to show that the “construction” of reality cannot ultimately divest itself of some criterion of truth, a criterion which itself cannot be reduced to mental construction. There are many complex and subtle ideas here and probably better expressions of the constructivist’s case than those that Berman canvasses, but still this is a solid challenge to any philosopher who wants to reject some type of realism and retain a commitment to the deliverances of science.
Chapter Four, “An Argument Against Classical Aristotelianism” takes on Aristotle directly, though here, as throughout the book, there is a dearth of references to any texts in the Aristotelian corpus. Berman argues that Aristotle fails to account for the very “commonalities” that he himself recognizes because he mistakenly ties himself to a doctrine of being which admits of degrees. According to Berman’s understanding of Aristotle, universals have less being than particulars. But the idea that “being” is not univocal is incoherent (pp. 106-7). Here, Berman’s resolve to ignore exegesis leads him to construct a straw man, which both misses the Aristotelian doctrine of being and also, in his desire to contrast Plato sharply with Aristotle, leads him to attribute to Plato a doctrine which is demonstrably not his, namely, the doctrine that for Plato “to be” is univocally attributable to both spatiotemporal and non-spatiotemporal beings and, one would suppose (although Berman does not mention this at all), the Idea of the Good which has being but is beyond or transcends the being of anything complex or in possession of an essence of any sort. Surprisingly, Berman does not consider Aristotle’s actual doctrine of being, which explicitly aims to confront the existential threat to metaphysics if it is the case that “being” is not univocal. Since Berman will not allow “categorical differences” in being for explanandum and explanans, he dismisses as unsupportable any attempt by Aristotle to put his universals to scientific use (p. 114).
Chapter Five, “Platonism Concerning the Objects of Science” is the heart of this book and also the most interesting part. Here, Berman argues that Platonic intelligible entities, non-spatiotemporal and not necessarily instantiated, are the only truth-makers for science, including we must remember, the social sciences (p. 123). Berman relies on a distinction found in Phaedo in the so-called autobiography of Socrates (although Berman does not cite this) between necessary conditions or “that without which not” and real causes of the commonalities of things in the sensible world. Berman calls these “causal-mechanical explanations” and “identity explanations”. The latter do not supplant the former, though the former cannot attain to scientific truth without the latter. The truth-makers for identity explanations are what Berman calls “scale-relative parameters” (p. 135). These are the quantitative expressions of the eternal scientific laws that allow us to understand both the static and dynamic structure of the sensible world. These parameters are scale-relative because the objects of science can be examined at multiple levels from the sub-atomic to the macroscopic and the laws pertaining to each need to be “scaled” accordingly. Since, according to Berman, the sensible world does not consist in Aristotelian substances, nothing scientific is lost if we “deconstruct” macroscopic entities into their constituents in searching for the laws governing their operations and their relations. According to Berman’s Platonism, what science aims to discover are the different kinds of quantitative relations expressed in equations that allow us to differentiate and ultimately understand things in the sensible world (p. 139). An interesting section applies the basic insight to modal truths, including impossibilities. So, “the explanations for modal truths are the genuinely existing specific mathematical relations, or lack thereof, between the different scale-relative parameters” (p. 151). Berman concludes by reaffirming his claim that what scientists really do when they consistently practice real science depends on the existence of non-spatiotemporal and, in principle, unobservable, entities (p. 161). In an all-too-brief concluding few pages, Berman extends this claim to the social sciences and to ethics and aesthetics, something that the Platonists will find congenial and the anti-Platonists even more strange than the basic claim regarding the natural sciences.
Berman’s strategy of trying to discover the philosophically defensible core of Platonism while ignoring exegesis altogether has evident pluses and minuses. The fifth chapter, especially, could be read by any philosophically minded person who had not even heard of Plato and who would thus be free of many prejudices. Such a reader might well come to the conclusion that, after all, Plato (or whoever holds the view defended in this book) may have a point. On the other hand, Berman’s commitment to treating Plato’s Platonism the way that Plato treats the sea god Glaucus in Republic Book Ten, yearning to reveal his true nature by removing from him the accretion of sea detritus, has real problems. For one thing, for Plato, mathematical explanations as expressed in equations do not yield knowledge or ultimate explanations, since the philosopher must ascend to the Forms themselves and then ultimately to the Idea of the Good to reach these. For another, Plato repeatedly insists on the indispensability of some sort of mind or νοῦς to deliver structure to the sensible world. Without the Good and the Demiurge, Berman’s Platonism may be open to attacks unmentioned in this book. At the same time, one must admit that Berman’s Platonism turns out to be a very respectable alternative to an array of anti-Platonic doctrines.