The estimated reading time for this post is 8 minutes.
In order to keep in touch with what happens in historiography, I sometimes spend a few days reading the introductions of recent historical publications. In a relatively efficient way, it gives me the comfortable feeling that I am still aware of what historians claim they are doing. Sometimes, however, I remind myself to read the whole book if I get the chance; and once or twice, when I do get that chance, the book completely and utterly blows me away. This is what Daryn Lehoux’s What Did the Romans Know did to me, and in this post I hope to give you an impression of why it did and why you should read it too.
What Did the Romans Know is not just a book about natural knowledge in the Roman period; it is at the same time an exercise in philosophy of science and philosophy of history. That is, it thematizes better than any historical work I’ve seen so far the question of what we are to make of the fact that when interpreting ancient science, we have to take into account that our culture has its own science as well. We come to our research with strong beliefs about what the world looks like, and with almost equally strong beliefs about what it is that gives us access to this world – in short, about what it means to do science. In Rome, we find a civilization that does these things very differently. What role do our own beliefs play in interpreting this apparently alien culture, and how do the historical insights acquired thus reflect upon the status of our own beliefs? Lehoux deals with these meta-questions, in the meantime bringing the Romans closer to us than we might have thought.
Lehoux starts out by discussing the status of divination according to Cicero, in a period that was fated to be the end of the Republican era. According to Lehoux, thoroughly contextualizing debates about divination means that we do not see it as “something to be believed in” (p. 28), but, like Roman religion in general, something that is inextricably connected to the functioning of the political system. Cicero is, of course, very much concerned with justifying and safeguarding the Republic, and he grounds its legitimacy in a law given by nature itself. This is where auspices and other instruments of divination acquire their status from as well: as a part of political duty. When talking about nature, the state and the gods are always nearby; Cicero believes that knowledge of nature is necessary for a proper relationship with the gods and the state.
After staging these interrelations between science, ethics and theology, Lehoux can dive into the question of what precisely is the relation between ‘law’ and ‘nature’ – a question that resonates strongly with the historiography of the scientific revolution. The concept of laws of nature after all was an essential and distinctive aspect of modern science. Or wasn’t it? Lehoux thinks not. He carefully explores how legal metaphors pervade Lucretius’ De rerum natura and other Latin authors, and how the idea of law is commonly used to refer to regularities in nature. The crossover goes two ways: there are ‘laws of nature’, but there is also ‘natural law’: human law is supposed to derive from the order of nature. There has never been a real antithesis between nomos and physis, not even in classical Greece, Lehoux claims (p. 59). And yes, for any reasonable definition of a natural law, Roman science admitted the possibility of such laws, and, when we look at the content of its theories, formulated them – Ptolemy “is neither vague nor unmathematical” about his explanation of planetary motion (p. 69). This is putting Roman science in its context and taking it seriously at the same time.
But science and ethics or law interact in yet another way. In a chapter on Seneca’s Natural questions, Lehoux brilliantly analyzes the rhetorical function that observations play in the argument, and the judicial phrasing that Seneca employs when he uses those observations to “move from what is agreed to what is undecided” (p. 92). The point is, as Lehoux says, that “in physics as in forensics, the main trick lies in convincing everyone that the witness is indeed a good one” (p. 95) – an observation reminding of Steven Shapin’s analysis of Boyle’s ‘literary technology’. In Seneca’s work, the reader becomes the judge in a debate in which selected observation claims play an important role.
This naturally flows into another chapter about the problem of observation. Here Lehoux reads Ptolemy and Galen as being urgently engaged with questions about the reliability of sense perception. The reason was the presence of vociferous skeptical philosophers; Galen relates how he was just about to perform an anatomical demonstration when a philosopher interrupted him and asked why the audience should believe the evidence of his senses. Galen stormed out of the room in anger. This was an intellectual context that demanded theories about the mechanisms of seeing – “ancient optics”, Lehoux warns us, “is not about light, it is about vision” (p. 112). Usually, theories of vision supposed that it worked by ‘extramission’: rather than taking in light, vision started with the eye, which sent out a force that contacted objects in the world and passed information about them to the eye. Galen and Ptolemy bolstered their extramissionist theories against skepticism by considering the relation between the world and the brain as causal. While the senses were simply affected in a certain way by certain kinds of objects (‘like’ affecting ‘like’) and were therefore reliable in principle, moving from sensory information to the world required judgment – a faculty again modelled upon legal procedures (p. 126).
All this accumulates very naturally to an impressive picture of the theoretical sophistication of Roman science. In chapter six, Lehoux tries to convince us that the Romans should be taken seriously as well when it comes to a seemingly ludicrous, almost frivolous trope: the claim that rubbing a magnet with garlic cancels its attractive power. Here we see a double hermeneutic in action, for Lehoux proposes to ask “not just […] why Pliny believed such silly things, but simultaneously why we think these beliefs are silly” (p. 134).
The question of what intellectual context explains the belief in this (nonexistent) phenomenon is actually rather easy to answer: it falls within a larger class of cases in which sympathetic and antipathetic substances influence each other. This would have been worth pointing out anyway, but Lehoux’s point turns out to be more subtle: it is not just that here we have a theory that was so universally believed that experience did not matter to it. It is that we have a theory that fitted within the world-view so well that it could function as an empirical fact. The crucial move in this chapter is that even though experience may be seen as the final arbiter of belief, it often happens that “inference and testimony […] bleed over into the category of experience”. (p. 145) It is not just dogmatism or even theory-ladenness that Lehoux is getting at; it is our “sloppiness with the very category of the empirical”. (p. 150)
For this sloppiness is ours as well. We too know very well what happens when we rub garlic on a magnet – nothing – without ever trying it: our knowledge about the world and our corresponding categories and classifications are such that it is immediately obvious that garlic and magnetism have nothing to do with each other. But it was just as obvious to the Romans that they did, and just as reasonable that they did not feel the need to test this – or rather felt that this belief was already being corroborated by experience all the time. Hence their confident formulations: “None should be ignorant […] that because of antipathy garlic rubbed on the magnet impedes it in its natural action.” (p. 138) The crux of Lehoux’s argument is how much he shows our epistemic situation to be like that of the Romans: we know just as well as they did what happens to the magnet, and our knowledge bears the same relation to our experience as theirs. Only, we know what happens to be the opposite.
This new historical awareness informs the later chapters of the book. After showing in two chapters (which we will skip here only for considerations of space) the plausibility of ancient astronomy and of the idea that the cosmos was rational and divine that lay behind most large-scale attempts at explanation, Lehoux moves on to two chapters in which he sketches the philosophical ramifications of his study. Aptly, these chapters come last, since our awareness of the coherence of Roman science turns out to feed back into the philosophy of (history (and) of) science.
It does so in the form of questions about realism and relativism. What are we to make of the fact that Roman descriptions of the world cohered so well with each other and with experiences of the world? How does this reflect upon the status of our own beliefs? Realism has to confront the historical problem that our epistemic situation is hard to distinguish in principle from that of the ancients. Lehoux even quotes a beautiful version of Hilary Putnam’s ‘miracle argument’: a classical Greek author saying that “because of the near perfect accuracy at which [medicine] has managed to arrive, I think we should reckon the things it has discovered – wondrous, were they from complete ignorance – as having been rightly and truly uncovered, and not the product of accident.” (p. 205). However, relativism comes with the hermeneutical problem that we understand the ancients in part because they seem to inhabit the same world, and that we cannot simply shed this resource. “All the theories we have been discussing in this book are theories about something, the world, that persists and whose observable behavior in the here and now is indispensable to our understanding of what ancient science is.” (p. 232)
Lehoux finds himself still grappling with these problems towards the end of the book, but his arguments seem to converge towards something between coherentist pragmatism and a weak form of realism, where people in many different contexts can at least be justified in believing that the entities posited by their theories really exist, even if the content of the theories about which they are realists may be historically contingent (p. 242).
I happen to find this very close to completely agreeable. However, it is not Lehoux’s precise philosophical commitments in the conclusion of his book for which I am recommending it to you. Rather, it is the eminent clarity with which he explicates ‘what the Romans knew’, and the depth of his reflections upon what it means for us to realize what they were doing – a depth that is never bought at the cost of clarity. If you are interested not just in the history of science but also in the question of what it means for how we think about knowledge, read this book.
 ‘Nature, Gods, and Governance’, 21-46.
 ‘Law in nature, nature in law’, 47-76.
 ‘Epistemology and judicial rhetoric’, 77-105.
 Steven Shapin, ‘Pump and circumstance: Robert Boyle’s literary technology’ in: H.M. Collins, T.J. Pinch, S. Shapin ed., Social studies of science (London, Beverly Hills, New Delhi) 481-520.
 ‘The embeddedness of seeing’, 106-132.
 ‘The trouble with taxa’, 133-154.
 ‘The long reach of ontology’, 155-175; ‘Dreams of a final theory’, 176-199.
 ‘Of miracles and mistaken theories’, 200-223; ‘Worlds given, worlds made’, 224-242.